Technical Field The present invention relates to a super high-speed fluid propulsion apparatus, and more particularly, to such a water jet-type super high-speed fluid propulsion apparatus in which output water is not nearly diffused even when rotating at a high speed.

Background Art In general, a conventional propeller is a propulsion device which pushes fluid backward along blade surfaces in a screw motion fashion using a helical pitch blade so as to create a thrust or propulsive force to cause the fluid to push a moving body forward with its reaction. For such a conventional propeller, fluid pressure increases at the front side of the blades but decreases at the rear side of the blades when the propeller rotates. In this case, a difference in fluid pressure between the front and rear sides of the blades results in a change in momentum of the fluid moving past the propeller, which creates the thrust or propulsive force of the propeller. However, in the case where the propeller rotates at a high speed in order to produce a larger thrust, low pressure areas are formed at the rear side of the blade as the fluid accelerates around and moves past the blades. If this pressure falls far enough, then the fluid will reach its vapor pressure, at which time the fluid, like boiling water, vaporizes and forms small bubbles of gas, to thereby cause a cavitation phenomenon. This ultimately makes it difficult to further improve the performance of the propeller. In addition, the conventional propeller is relatively very heavy, generates much noise during its high-speed rotation and makes it difficult to control its rotational speed. Also, the prior art propeller is disadvantageous in that it has a limitation in size. Moreover, for the conventional propeller, as it rotates at a higher speed, the fluid moving past the rear side of the blade and pushed backward is spread out or diffused more widely, but does not move in a straight line form. This results in further increased diffusion of output fluid, which leads to a deterioration in propulsion efficiency. Further, the blades of the conventional propeller have a streamlined, airfoil-type or ogive-type shape in cross section much like an aircraft wing, making it difficult to manufacture. A duct propeller is known which partially improves the above shortcomings. This prolusion device is designed such that a duct is fixedly mounted around a propeller. In the case where the duct is shaped so as to accelerate fluid, the duct propeller can serve to increase the propulsion efficiency of a highly loaded propeller. On the other hand, in the case where the duct is shaped so as to decelerate the fluid, the duct propeller can act to increase the static pressure in the propeller to delay the generation of the cavitation. However, such a fixed-type duct propeller embraces a problem in that it is difficult to achieve a sufficient effect for both improvement of the propulsion efficiency and suppression of the cavitation generation when the flow velocity of the fluid rises up to above a certain level. As another conventional prior art, a fluid injection-type propulsion device is known which produces a thrust or propulsive force by powerfully injecting fluid backward. In the case where such a fluid injection-type propulsion device is applied to a ship, it is called "a water jet propeller". The conventional screw-type propeller moves a ship forward with the aid of its rotational force whereas such a water jet-type propeller moves the ship forward by sucking water through a sucking tube into an impeller installed inside a ship body and injecting it. Since a ship equipped with a typical water jet propeller exhibits a remarkable decrease in diffusion of output water as compared to that with the screw-type propeller, it has an advantage of enhancing the propulsion efficiency of the propeller. Therefore, the water jet propeller enables the speed of the ship to be increased. Also, the higher the speed of the water jet propeller becomes, the greater the propulsion efficiency thereof becomes. In addition, since the water jet propeller is installed inside the ship body, its noise and vibration level can be reduced. Moreover, the water jet propeller can normally operate in even places where water is shallow such that the ship with the screw- type propeller cannot travel, or in even places where many fishing nets and ropes are set. However, for the conventional water jet propeller, it requires a large installation space for the propeller within the ship since the sucking tube and the impeller are installed inside the ship body. Also, such a water jet propeller has a limitation in improving its propulsion efficiency due to the fact that it sucks and injects water with only the rotation of the impeller.

Disclosure of Invention Technical Problem The present invention is directed to a fluid propulsion apparatus which can address the above-mentioned problems and deficits occurring in the prior art propulsion devices. Therefore, it is an object of the present invention to provide an super high-speed fluid propulsion apparatus which can minimize the diffusion of output water even when rotating at a high speed similar to a conventional water jet propeller. It is another object of the present invention is to provide an super high-speed fluid propulsion apparatus having blades which can be formed in a convex shape by bending a flat plate material so as to be more simply and easily manufactured compared to a conventional propeller blade having an airfoil-type shape in cross section. Still another object of the present invention to provide a means for suppressing an increase in resistance caused by collision between the front tip of a propeller blade and fluid according to high speed rotation of a propeller. Yet another object of the present invention is to provide a rotator-type propulsion apparatus in which a hub, blades, a propeller opened at a front side thereof and having a sucked fluid passage, and a duct having a plurality of accelerating suction parts formed thereon are integrally formed so as to rotate together. A further object of present invention is to provide an super high-speed fluid propulsion apparatus in_ which accelerating inflow water additionally introduced from the outer peripheral surface of the duct rotating upon the high speed rotation of the propeller ' repeatedly continues to acceleratingly join the main-stream of fluid flowing straightly inside the duct so as to produce a more powerful thrust. A still further object of the present invention is to provide an super high-speed fluid propulsion apparatus in which a trumpet-shaped duct are interposed between blades of the propeller, so that fluid flowing inside the blades is accelerated within a plurality of trumpet-shaped ducts partially nested within one another, thereby improving propulsion efficiency.

Technical Solution To accomplish the above object, an super high-speed fluid propulsion apparatus according to the present invention- comprises a driving shaft installed at the rear portion or at the inside of a ship, and a propulsion unit coupled to the driving shaft and adapted to rotate in response to rotation of the • driving shaft, wherein the propulsion unit includes a propeller having a hub connected to the driving shaft and a plurality of blades arranged around the hub in such a fashion as to be integrally formed with the hub, and a duct provided at the outer end of the propeller in such a fashion as to be integrally formed with the propeller and having a plurality of accelerating suction parts formed on the outer peripheral surface of the duct in such a fashion as to be opened outwardly, whereby when the duct rotates simultaneously with the propulsion unit, fluid flowing outside the duct is sucked into the propulsion unit via the accelerating suction parts.

Advantageous Effects As described above, according to the super high-speed fluid propulsion apparatus of the present invention, since a hub 110, a plurality of blades 111 and a duct 113 are integrated into a single rotating unit, they can rotate simultaneously to achieve increased propulsion efficiency owing to powerful injection of accelerated fluid. Particularly, the super high-speed fluid propulsion apparatus of the present invention sucks in fluid with a great pressure through a plurality of accelerating suction parts formed on the outer peripheral surface of the duct when rotating at a high speed, so that it can repeatedly continue to supply fluid to the inside thereof, thereby additionally obtaining powerful injection fluid output. Further, in the case where the present invention is applied to, a ship, it can structurally solve the problem in thatj when operating a propulsion apparatus using a conventional propeller at a high speed, cavitation occurs in the propeller, which results in a decrease in thrust of the propulsion apparatus. In addition, even during the high-speed rotation of the propulsion apparatus less noise is generated, and the size and shape of the propulsion apparatus can be variously modified. In case of application of the inventive propulsion apparatus to a ship, its installation location can be freely altered inside or outside the ship. Moreover, even though the inventive propulsion apparatus rotates at a high speed, it does not exhibit diffusion phenomenon of fluid in which output fluid is widely spread, thereby producing water jet-type output fluid dissimilar to a conventional propulsion apparatus. Also, since the present invention enables coupling of a reverser thereto to create an inverse thrust or propulsive force, it is possible to simply and easily produce' the inverse thrust through the reverser without reverse-rotation and starting of an engine. Accordingly, upon the reverse propulsion of the inventive propulsion apparatus, an external environment does not affect1 the entire propulsion apparatus and mobile power is improved. In particular, the preserit invention has an advantage in that the front tips of the blades intensively colliding with ■ fluid when rotating in the fluid and the front ends of the accelerating suction parts are formed in an acute shape like the cutting edge of a knife, so that when a propulsion unit collides with the fluid while rotating at a high speed, both diffusion of output fluid and collision resistance at its collision cross section are minimized and generation of • cavitation is suppressed. Further, .'since the propeller blades of the present invention are formed by bending a flat plate, they can be more simply and easily fabricated as compared to a conventional blade having -a streamlined, airfoil-type or ogive-type shape in cross section. Specially, in the case where a trumpet-shaped duct is applied to the present invention -irv a multi-stage mode, fluid is accelerated around the duct many times while moving past the duct, thereby creating a strong thrust accordingly. In addition, since the present invention provides a buoyancy forming part, downward deflection of the fluid propulsion apparatus due to its own weight is partially offset. The present invention has an advantage in that since a front propulsion unit, a middle propulsion unit and a rear propulsion unit of various types illustrated in respective embodiments can be implemented in a combination of various forms or alone, it is possible to freely modify the configuration of the propulsion units to conform to their applications. That is, the inventive propulsion unit can be used as a propulsion unit itself or a pump transporting various types of fluid such as water, oil, gas or the like depending on how respective propulsion units are combined to be implemented. For example, it is preferable to select a propulsion unit having a simple inner structure illustrated in the fourth or fifth embodiment in case of fluid with a relatively high viscosity such as oil, and it is more preferable to select a propulsion unit having a complicated inner structure illustrated in the first or second embodiment in case of fluid with a relatively low viscosity such as gas.

Brief Description of the Drawings The above and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings, in which: FIGs .1 to 29 illustrate the structure of an super high-speed fluid propulsion apparatus according to a first embodiment of the present invention; FIG. 1 is a cross-sectional side view illustrating a state in which the super high-speed fluid propulsion apparatus of the present invention is applied to a ship; FIG. 2 is a vertical cross-sectional view illustrating the super high-speed fluid propulsion apparatus of the present invention; FIG. 3 is an exploded perspective view illustrating essential parts of the super high-speed fluid propulsion apparatus of the present invention; FIG.4 is a vertical cross-sectional view illustrating a driving shaft part of the super high-speed fluid propulsion apparatus of the present invention; FIG. 5 is a perspective view illustrating a front propulsion unit of the inventive super high-speed fluid propulsion apparatus; FIG. 6 is a side view illustrating the front propulsion unit of the inventive super high-speed fluid propulsion apparatus; FIG. 7 is a top plan view illustrating the front propulsion unit of the inventive super high-speed fluid propulsion apparatus; FIG. 8 is a cross-sectional view taken along the line A-A of FIG. 6; FIG. 9 is a cross-sectional view taken along the line B-B of FIG . 7 ; FIG. 10 is a cross-sectional view taken along the line C-C of FIG. 7; FIG. 11 is a cross-sectional view taken along the line D-D of FIG. 7; FIG. 12 is a perspective view illustrating a middle propulsion unit of the inventive super high-speed fluid propulsion apparatus; FIG. 13 is a side view illustrating the middle propulsion unit of the inventive super high-speed fluid propulsion apparatus, and FIG. 14 is a top plan view illustrating the middle propulsion unit of the inventive super high-speed fluid propulsion apparatus; FIG. 15 is a cross-sectional view taken along the line E-E of FIG. 14, and FIG. 16 is a cross-sectional view taken along the line F-F of FIG. 14; FIGs. 17 and IB are perspective views illustrating a rear propulsion unit of the -inventive super high-speed fluid propulsion apparatus when viewed in different directions; FIG. 19 is a side view illustrating the rear propulsion unit of the inventive super high-speed fluid propulsion apparatus, and FIG. 20 is a top plan view illustrating the rear propulsion unit of the inventive super high-speed fluid propulsion apparatus; FIG. 21 is a cross-sectional view taken along the line G-G of FIG. 20; FIG. 22 is a perspective view illustrating a guide part of the inventive super high-speed fluid propulsion apparatus; FIG. 23 is a cross-sectional view taken along the line H-H of FIG . 22 ; FIGs. 24 and 26 are vertical cross-sectional view illustrating a crown-shaped reverse means of the inventive super high-speed fluid propulsion apparatus in non- activated and activated states; FIGs. 25 and 27 are partially enlarged views of FIGs. 24 and 26; FIG. 28 is a perspective view illustrating a collapsible plate of the crown-shaped reverse means; FIG. 29 is a cross-sectional view taken along the line I-I of FIG. 28; FIGs. 30 to 46 'illustrate the structure of an super high-speed fluid propulsion apparatus according to a second embodiment of the present invention wherein, FIG. 30 is a cross-sectional side view illustrating a state in which the super high-speed fluid propulsion apparatus of the present invention is applied to a ship; FIG. 31 is a vertical cross-sectional view illustrating the super high-speed fluid propulsion apparatus of the present invention; FIG. 32 is an exploded perspective view illustrating essential parts of the super high-speed fluid propulsion apparatus of the present invention; FIG. 33 is an assembled perspective view illustrating the essential parts of the inventive super high-speed fluid propulsion apparatus in FIG. 32; FIG. 34 is a partial cross-sectional perspective view of FIG. 33; FIG. 35 is a perspective view illustrating a front propulsion unit of the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention; FIG. 36 is a side view illustrating the front propulsion unit of FIG. 35; FIG. 37 is a cross-sectional view taken along the line A-A of FIG. 36; FIG. 38 is a perspective view illustrating a middle propulsion unit of the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention; FIG. 39 is a side view illustrating the middle propulsion unit of FIG. 38; FIG. 40 is a cross-sectional perspective view taken along the line B-B of FIG. 39; FIG. 41 is a top plan view of FIG. 40; FIG. 42 is a cross-sectional top plan view taken along the line C-C of FIG. 39; FIGs. 43 and 44 are perspective and partial side views illustrating a second blade of the inventive super high¬ speed fluid propulsion apparatus; FIG. 45 is a cross-sectional view illustrating a rear propulsion unit of the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention; FIG. 46 is a schematic fluid flow diagram of the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention; FIGs. 47 to 48 illustrate the structure of an super high-speed fluid propulsion apparatus according to a third embodiment of the present invention; FIG. 4<7 is a cross-sectional view illustrating the super high-speed fluid propulsion apparatus of the present invention; FIG. 48 is a perspective view illustrating the super high-speed fluid propulsion apparatus of the present invention; FIGs. 49 to 52 illustrate the structure of an super high-speed fluid propulsion apparatus according to a fourth embodiment of the present invention; FIG. 49 is a perspective view illustrating a rear propulsion unit of the super high-speed fluid propulsion apparatus according to the fourth embodiment of the present invention; ' FIG. 50 is a cross-sectional perspective view of FIG. 49; FIG. 51 is a cross-sectional view of FIG. 49; FIG. 52 is a cross-sectional view illustrating a modified embodiment of FIG. 51; > FIGs. 53 and 54 illustrate the structure of an super high-speed fluid propulsion apparatus according to a fifth embodiment of the present invention; FIG. 53 is a cross-sectional view illustrating the super high-speed fluid propulsion apparatus of the present invention; and FIG. 54 is a cross-sectional view illustrating a modified embodiment of FIG. 53; FIG. 55 illustrates a state in which the super high¬ speed fluid propulsion apparatus of "the present invention is installed inside a ship. <Explanation on Reference Numerals of Essential elements of Drawings> 1: ship 10: propulsion unit 20: front propulsion part 21: middle propulsion part 22: rear propulsion part 23: guide part 24: reverser 25: housing 100: front propulsion unit 101: middle propulsion unit 102: rear propulsion unit 110: first hub 111: first blade 112: first propeller 113: first duct 113a: first peripheral wall part 113b: first incision part 113c: first rib 113d: first reinforced rib 113e: first directional rudder 113f: first diffusion-preventing part 113g,113h: first edge-shaped front tip 114: first accelerating suction part 114a, 114b: first suction part 120: second hub 121: second blade 122: second propeller 123: second duct 123a: second peripheral wall part 123b: second incision part 123c: second reinforced rib 123d, 123e: second edge- shaped front tip 124: second accelerating suction part 124a, 124b, 124c: second suction part 130: third hub 131: third blade 132: third propeller 133: third duct 133b: inclined outer peripheral edges 133c: third incision part 133d: third reinforced rib 133e,133f: third edge- shaped front tip 133g: spiral protrusion 134: third accelerating suction part 134a, 134b, 134c: third suction part 140: fourth hub 141: circular tube-type duct 142: guide blade 143: bracket 150: guide tube 151: crown-shaped reverse means 152: drive means 153: fan-shaped collapsible plate 154: cylinder 155,156: dual plunger 155a, 15βa: connecting member 157,158: connecting lever 160: cover 200 driving shaft 210: first shaft 220 second shaft 230: third shaft 310 first hub 320: second hub 330 third hub 311: first blade 312 first propeller 313: first trumpet-shaped duct 314 first accelerating suction part 315: first buoyancy forming part 316: discharge part 317: streamlined tail 318: first coupling part 321: second blade 322: second propeller 323: second trumpet-shaped duct 323-1: second front trumpet-shaped duct 323-2: second rear trumpet-shaped duct 324: second accelerating suction part 324-1: second front accelerating suction part 324-2: second rear accelerating suction part 325: second buoyancy forming part 328: second coupling part 331: third blade 332: third propeller 333: third trumpet-shaped duct 333-1: third front trumpet-shaped duct 333-2: third rear trumpet-shaped duct 334: third accelerating suction part 334-1: third front accelerating suction part 334-2: third rear accelerating suction part 335: third buoyancy forming part 338: third coupling part 333a: fluid reflective plate 334-la: third front wing 324-2b: reinforced rib 350: streamlined blade 360: housing 361: grid 416: discharge part 430: third coupling part 433-1: fourth trumpet-shaped duct 433a: fourth fluid reflective plate 434-1: fourth accelerating suction part 434-la: fourth wing 44-lb: fourth reinforced rib 500: suction opening

Best Mode for Carrying Out the Invention The present invention having a basic construction as described above makes it possible to variously modify each constituent element, and reference will now be made in detail to the first embodiment as the most basic preferred embodiment and the second to fifth embodiments as its modified embodiments of the present invention with reference to the attached drawings .

(First Embodiment) The construction of the fluid propulsion apparatus of the first embodiment will now be schematicadly described hereinafter. First, a driving shaft consists of multiple shafts (first, second and third shafts) , and to the multiple shafts is coupled a front propulsion unit, a middle propulsion unit, a rear propulsion unit and a guide part, respectively. The front propulsion unit includes a first propeller having a first hub fixedly connected to the first shaft and a plurality of first blades arranged around the first hub in such a fashion as to be integrally formed with the first hub, and a first duct provided at the outer end of the first propeller in such a fashion as to be integrally formed with the first propeller and having a plurality of first accelerating suction parts formed on the outer peripheral surface of the first duct in such a fashion as to be opened outwardly. The first blades of the first propeller of the front propulsion unit are coupled to the first hub with it being formed in a spiral shape such that fluid flows from the front toward the back. The first blades entirely have a convex surface shaped by bending a flat plate in a bulged shape. The first duct has a first peripheral wall part of a circular tube shape formed at a lower portion thereof, and has a plurality of first incision parts formed at an upper portion thereof. The middle propulsion unit includes a second propeller having a second hub fixedly connected to the second shaft and a plurality of second blades arranged around the second hub . in such a fashion as to be integrally formed with the second hub, and a second duct provided at the outer end of the second propeller in such a' fashion as to be integrally formed with the second propeller and having a plurality of second accelerating suction parts protrudingly formed on the outer peripheral surface of the second duct. The rear propulsion unit includes a third propeller having a third hub fixedly connected to the third shaft and a plurality of third blades arranged around the third hub in such a fashion as to be integrally formed with the third hub, and a third duct provided at the outer end of the third propeller in such a fashion as to be integrally formed with the third propeller and having a plurality of third accelerating suction parts protrudingly formed on the outer peripheral surface of the third duct 133. The guide part includes a fourth hub fixedly connected to the third shaft, a plurality of guide blades arranged around the fourth hub in such a fashion as to be integrally formed with the fourth hub, and a circular tube-type duct coupled with the guide blades in such a fashion that the front tips of the guide blades are securely coupled to the inner peripheral surface of the circular tube-type duct. The circular tube-type duct is fixed to a ship body by means of brackets, so that the guide part prevents the propulsion units from being shaken during the rotation of the propulsion units. To the rear side of the guide part may be coupled a reverser for creating an inverse thrust or propulsive force, if necessary. The reverser is constructed such that a crown-shaped reverse means is foldably coupled to a guide tube fixed to the rear portion of the guide part by means of a drive means. The crown-shaped reverse means consists of a plurality of fan-shaped collapsible plates, and the drive means is constructed such that a plurality of cylinders are fixed to the outer peripheral surface of the guide tube, and each of connecting members is coupled to the front end of a dual plunger connected to the cylinders. Also, a connecting lever is hingeably coupled at one end to each connecting member and connected at the other end to the collapsible plate. The accelerating suction parts of each propulsion unit enable fluid flowing outside each duct to be sucked into the blades along a circumferential direction of the duct. At this time, the sucked fluid is powerfully forcibly pushed backward by the rotating blades. Each propulsion units according to the present invention may be implemented independently. That is, it is possible to implement a method in which the front propulsion unit alone rotates without the middle and rear propulsion units so as to produce output water. Of course, it is also possible to separately implement the middle propulsion unit and the rear propulsion unit, respectively, through a little modification to their structures. Further, the front tip of the propeller blade of the present invention and the front end of each , accelerating suction part are characterized in that they are formed in an acute shape like the cutter edge of a knife. The rotating shaft of the present invention may be altered to a triple, shaft, a dual shaft, a single shaft, etc., and in the case where the rotating shaft is composed' of a multiple shaft, each shaft can rotate at different speeds. Accordingly, in the • case where respective propulsion ■ units arranged by each interval are connected in series to each shaft, the front ' propulsion unit, the middle propulsion unit and the rear propulsion unit can rotate at different speeds, respectively.' ' . The configuration of the first embodiment according to the present invention will be described in detail hereinafter with reference to the accompanying drawings. The first embodiment of the present invention is shown in FIGs. 1 to 29. FIG. 1 is a cross-sectional side view illustrating a state in which the super high-speed fluid propulsion apparatus of the present invention is applied to a ship, FIG. 2 is a vertical cross-sectional view illustrating the super high-speed fluid propulsion apparatus of the present invention, FIG. 3 is an exploded perspective view illustrating essential parts of the super high-speed fluid propulsion apparatus of the present invention, and FIG.4 is a vertical cross-sectional view illustrating a driving shaft part of the super high-speed fluid propulsion apparatus of the present invention. As shown in the drawings, a propulsion unit 2 is coupled to a driving shaft 200. The propulsion unit 2 is coupled to the driving shaft 200 and is adapted to rotate in response to rotation of the driving shaft. The propulsion unit 2 basically includes a propeller 12 having a hub 10 fixedly connected to the driving shaft and a plurality of blades 11 arranged around the hub 10 so as to be integrally formed with the hub, and a duct 13 provided at the outer end of the propeller 12 in such a fashion as to be integrally formed with the propeller. The propulsion unit 2 has a basic configuration as described above, but may be constructed in various types like a front propulsion unit 101, a middle propulsion unit 102 and a rear propulsion unit 103. A plurality of accelerating suction parts 14 are formed on the outer peripheral surface of the duct 13 so as to extend circumferentially outwardly from the outer peripheral surface of the duct 13 in such a fashion as to be opened outwardly. Fluid around the duct 13 being rotated is sucked into the propulsion unit 2 via the accelerating suction part 14 and then forcibly pushed toward the blades 11 inside the propulsion unit 2. Referring to FIGs. 1 to 4, a front propulsion unit 100 - is coupled to a first shaft 210 to form a front propulsion part 20, three middle propulsion units 101 are coupled to a second shaft 220 to form a middle propulsion part 21 and a rear propulsion unit 102 is coupled to a third shaft 210 to form a rear propulsion part 22. That is, an super high-speed fluid propulsion apparatus according to a first embodiment of the present invention includes the driving shaft 200, the front propulsion part 20, the middle propulsion part 21, the rear propulsion part 22 and the ςfμide part 23. The front ■ propulsion part 20, the middle propulsion part 21, the rear propulsion part' 22 and the guide part 23 are coupled to the .driving shaft in such a fashion as to be arranged in series. The driving shaft 200, as shown in FIG. 4, includes the first shaft 210, the second shaft 220 inserted into the first shaft 210 with it being backwardly protruded by a predetermined length, and the third shaft 230 inserted into the second shaft 220 with it being backwardly protruded by a predetermined length. The first, second and the third shafts' 210, 220 and 230 rotate at different speeds, respectively. The first shaft 210 and the second shaft 220 of the driving shaft 200 are coupled to . each other by means of bearings 240 and 241 interposed between the first shaft and the second shaft, and the second shaft 220 and the third shaft 230 of the driving ' shaft 200 are coupled to each other by means of bearings 242 and 243 ■ interposed between the second shaft and the third shaft. The first shaft 210 is fixed to an end of a first gear 251, which engages with a second gear 252 fixedly coupled to a first transmission shaft 250, so that the first shaft 210 receives a rotational force the transmission shaft 215. The second shaft 220 is fixed to an end of a third gear 254, which engages with a fourth gear 255 fixedly coupled to a second transmission shaft 253, so that the second shaft 220 receives a rotational force the second transmission shaft 253. An explanation and illustration on the driving source of the first, second and third shafts 210, 220 and 230 will be omitted since it employs a conventional technical means. As such, in the case where the super high-speed fluid propulsion apparatus of the present invention is applied to a ship, as shown in FIG. 1, it is mounted inside a housing 25 for preventing generation of noise and introduction of foreign substances, which is fixed to the stern of the ship 1 and has a suction opening 25a formed at the bottom thereof for sucking fluid into the housing. At the suction opening 25a is provided a grid 26 for interrupting the introduction of foreign substances. However, the present invention may be applied, for example, at a place where it is required to create a thrust or propulsive force through discharge of other fluids, at a place where it is only needed to powerfully discharge fluid, at a place where it necessary to forcibly feed fluid, or the like, besides a ship. FIG. 5 is a perspective view illustrating a front propulsion unit of the inventive super high-speed fluid propulsion apparatus, FIG. 6 is a side view illustrating the front propulsion unit of the inventive super high-speed fluid propulsion apparatus, FIG. 7 is a top plan view illustrating the front propulsion unit of the inventive super high-speed fluid propulsion apparatus, FIG. 8 is a cross-sectional view taken along the line A-A of FIG. 6, FIG. 9 is a cross-sectional view taken along the line B-B of FIG. 7, FIG. 10 is a cross-sectional view taken along the line C-C of FIG. 7, and FIG. 11 is a cross-sectional view taken along the line D-D of FIG. 7. Referring to FIGs. 5 to 11, the front propulsion unit 100 includes a first propeller 112 having a first hub 110 fixedly connected to the first shaft 210 and a plurality of first blades 111 arranged around the first hub 110 in such a fashion as to be integrally formed with the first hub, and a first duct 113 provided at the outer end of the first propeller 112 in such a fashion as to be integrally formed with the first propeller and having a plurality of first accelerating suction parts 114 each extending circumferentially outwardly from the outer peripheral surface of the first duct 113 in such a fashion as to be opened outwardly. The first blades 111 of the first propeller 112 are coupled to the first hub with it being formed in a spiral shape such that fluid flows from the front toward the back. The first blades entirely have a convex surface shaped by bending a flat plate in a bulged shape. The first accelerating suction parts 114 of the front propulsion unit 100 enables fluid flowing outside the first duct 113 to be sucked into the first blades 111 along a circumferential direction of the first duct, so that the sucked fluid is powerfully forcibly pushed backward by the rotating blades. The first duct 113 serves to prevent the diffusion of fluid and induce the flow of fluid when rotating at a high speed, and rotates together with the first propeller 112 since it is coupled integrally with the first propeller 112. As shown in FIG. 5, the first duct 113 has a first peripheral wall part 113a of a circular tube shape formed at a lower portion thereof, and has a plurality of first incision parts 113b formed at an upper portion thereof. Accordingly, it can be seen from FIG. 5 and FIG. 7 that the upper portion of the first duct 113 has one end formed to extend radially outwardly from the outer end of each first blade (111) and the other end formed with the plurality of first incision parts (113b), and is formed in such a fashion that the distance between the upper portion of the first duct 113 and the central axis line of the first hub 110 is decreased gradually as it goes from one end of the upper portion of the first duct toward the other end thereof. Accordingly, a certain space is defined between one end of the upper portion of the first duct and each first incision part 113b to thereby form each first accelerating suction part 114. The first accelerating suction part 114 is provided with a first rib 113c, and if necessary may be provided at an intermediate portion thereof with at least one or more first reinforced ribs 113d to form a plurality of first suction parts 114a and 114b. In addition, as shown in FIGs. 9 and 10, at the inner wall of each of the first suction parts 114a and 114b is formed a first directional rudder 113e for changing the flow direction of fluid acceleratingly sucked into the first suction parts to induce the fluid backward. Each front end of the first rib 113c and the first reinforced rib 113d of each first accelerating suction part 114 is formed in an acute shape like the cutting edge of a knife, which is called "a first edge-shaped front tip 113g". The front end of an acute shape like the cutting edge acts to minimize diffusion phenomenon of fluid occurring at its collision section and collision resistance when colliding against the fluid, and suppress generation of cavitation. The front end of a sharp shape like the cutting edge of a knife is also formed at a first diffusion-preventing part 113f, which is called λλ a first edge-shaped front tip 113h". The first edge-shaped front tip 113h has the same working effect as the first edge-shaped front tip 113g. As shown in FIGs. 5 and 7, the first diffusion- preventing part 113f is configured such that the front end of each first blade 111 is slightly bent by a certain width inward from a curved surface of the blade 111, and a lower portion 113i of the first diffusion-preventing part 113f, which meets the upper end of the first accelerating suction part 114, extends in a straight line, but not bent inward from the curved surface of the blade 111. Such a bent structure of the blade 111 serves to prevent fluid from being diffused outwardly from the blade 111 during the high-speed rotation of the blade 111. As shown in FIGs 5 and 9, the first rib 113c and the first reinforced rib 113d of each first accelerating suction part 114 are formed slantly. Such a tilting structure of the ribs is aimed at smoothly inducing the flow of fluid introduced into the first accelerating suction part backwardly without any resistance of fluid. A portion in which the first rib 113c is fixedly coupled to the first duct 113 is formed with a second diffusion-preventing part 113j which is shown as a protrusion projected in a triangle shape in the drawing. This second diffusion-preventing part 113j functions to partially interrupt flow of fluid sucked into the first blades 111 from being diffused to the outside of the first duct 113 while the fluid collides against and is reflected at a curved surface inside each blade 111. Thus, the protruding height of the second diffusion-preventing part 113j is determined depending on the curvature of the blade 111. However, the front propulsion unit of the present invention may employ a general screw-type propeller, but not the above-mentioned complex type propeller blade. In this case, the conventional screw-type propeller is formed integrally with the duct to construct the front propulsion unit. At the same time, the duct is formed on the outer peripheral surface thereof with an accelerating suction part for additionally sucking fluid flowing around the duct into the duct, so that the sucked fluid joins the output fluid of the screw-type propeller, thereby producing more powerful output water. FIG. 12 is a perspective view illustrating a middle propulsion unit of the inventive super high-speed fluid propulsion apparatus, FIG. 13 is a side view illustrating the middle propulsion unit of the inventive super high¬ speed fluid propulsion apparatus, FIG. 14 is a top plan view illustrating the middle propulsion unit of the inventive super high-speed fluid propulsion apparatus, FIG. 15 is a cross-sectional view taken along the line E-E of FIG. 14, and FIG. 16 is a cross-sectional view taken along the line F-F of FIG. 14. Now, the detailed construction of the middle propulsion unit will be described hereinafter with reference to FIGs. 12 to 16. As shown in FIG. 12, the middle propulsion unit 101 includes a second propeller 122 having a second hub 120 fixedly connected to the second shaft 210 and a plurality of second blades 121 arranged around the second hub 110 in such a fashion as to be integrally formed with the second hub, and a second duct 123 provided at the outer end of the second propeller 122 in such a fashion as to be integrally formed with the second propeller and having a plurality of second accelerating suction parts 124 protrudingly formed on the outer peripheral surface of the second duct 123. The second blades 121 of the second propeller 122 are coupled to the second hub 120 with it being formed in a radially inclined shape such that fluid flows from the front toward the back. The second accelerating suction parts 124 of the middle propulsion unit 101 enables fluid flowing outside the second duct 123 to be sucked into the second blades 121 along a circumferential direction of the second duct, so that the sucked fluid is powerfully forcibly pushed backward by the. rotating blades. The second duct 123 includes a second peripheral wall part 123a of a circular tube shape. The second peripheral wall part 123a has a plurality of second incision parts 123b formed thereon in such a fashion that each second incision part is positioned adjacent to the front tip of each second blade 121 and connected fluid-communicatively with each second accelerating suction part 124. In this case, the second accelerating suction part 124 is constructed such that it externally surrounds the second incision part 123b. The second accelerating suction part 124 may be provided at an intermediate portion thereof with at least one or more second reinforced ribs 123c, if necessary, to form a plurality of second suction parts 124a, 124b and 124c. The first accelerating suction part 114 is provided with a first rib 113c, and if necessary may be provided at an intermediate portion thereof with at least one or more first reinforced ribs 113d to form a plurality of first suction parts 114a and 114b. In addition, as shown in FIGs. 9 and 10, at the inner wall of each of the first suction parts 114a and 114b is formed a first directional rudder 113e for changing the flow direction of fluid acceleratingly sucked into the first suction parts to induce the fluid backward. The front end 123d of the second peripheral wall part and the front end 123e of the second reinforced rib 123c of each second accelerating suction part 124 are formed in an acute shape like the cutting edge of a knife, which is called λλa second, edge-shaped front tip". The second edge-shaped front tips 123d and 123e act to minimize diffusion phenomenon of fluid occurring at its collision section and collision resistance when colliding against the fluid during its high-speed rotation, and suppress generation of cavitation. Also, as shown in FIG. 2, an annular insertion recess 126 is formed between one second duct 123 and another second duct 123 which are adjacent to each other, so that a sealant of ring shape is inserted thereto. The sealant is fabricated of a material having good resiliency and rigidity. Typically, urethane rubber will be used as the sealant. The sectional configuration of the ring-shaped sealant will be described with reference to a picture depicted in a small circle of FIG. 2. The sealant 125 filled with air/fluid is formed internally with a hole 125a having an oval-shaped cross section of which width is increased gradually as it goes from a smaller circular arc portion at the front toward a larger circular arc portion at the back. The larger circular arc portion of the oval hole is oriented toward an inner gap 126a, and the smaller circular arc portion of the oval hole is oriented toward an outer gap 126b. In addition, an incision hole 125b is formed at the rear of the oval hole 125a of the sealant 125. In the case where pressure raises at the rear portion of the second duct 123, when the oval hole 125a is applied with pressure, a small change in pressure of the larger circular arc portion causes a large change in pressure of the smaller circular arc portion so that the smaller circular arc portion of this sealant 125 is expanded relatively more. Also, as the outside of the sealant 125 is more strongly applied with the pressure inside interconnection portion between adjacent second ducts 123, the smaller circular arc portion of the sealant 125 is expanded more strongly. That is, as the second duct 123 rotates at a higher speed, the pressure inside the second duct raises greater. But, since the expansion pressure of the sealant 125 is increased accordingly in response to such a greater increase in internal pressure of the second duct, it is possible to improve a sealing effect in which leakage of fluid at the connection portion between the adjacent second ducts 123 is prevented. This configuration .of the sealant 125 can be commonly applied to the interconnection portions between respective propulsion units. FIGs. 17 and 18 are perspective views illustrating a rear propulsion unit of the inventive super high-speed fluid propulsion apparatus when viewed in different directions, FIG. 19 is a side view illustrating the rear propulsion unit of , the inventive super high-speed fluid propulsion apparatus, FIG. 20 is a top plan view illustrating the rear propulsion .unit of the inventive super high-speed fluid propulsion apparatus, and FIG. 21 is a cross-sectional view taken along the line G-G of FIG. 20. Now, an explanation on the detailed construction of the rear propulsion unit will be made hereinafter with reference to FIGs. 17 to 21. The rear propulsion unit 102 includes a third propeller 132 having a third hub 130 fixedly connected to the third shaft 220 and a plurality of third blades 131 arranged around the third hub 130 in such a fashion as to be integrally formed with the third hub, and a third duct 133 provided at the outer end of the third propeller 122 in such a fashion as to be integrally formed with, the third propeller and having a plurality of third accelerating suction parts 134 protrudingly formed on the outer peripheral surface of the third duct 133. The third blades 131 of the third propeller 132 are coupled to the third hub 120 with it being formed in a radially inclined shape such that fluid flows from the front toward the back. The third accelerating suction parts 134 of the rear propulsion unit 102 enables fluid flowing outside the third duct 133 to be sucked into the third blades 131 along a circumferential direction of the third duct, so that the sucked fluid is powerfully forcibly pushed backward by the rotating blades. The front portion of the third duct 133 is formed in a circular tube shape and the rear portion of the third duct is formed in a tapered tubular shape of which diameter is decreased gradually as it goes from the front toward the back. The third duct 133 having a third peripheral wall part 133a of a circular tube shape and a plurality of third accelerating suction parts (134) protrudingly formed on the outer peripheral surface of the third peripheral wall part. The third peripheral wall part 133a has a plurality of third incision parts 133c formed thereon in such a fashion that each third incision part is positioned adjacent to the front tip of each third blade 131 along a tapered outer peripheral edge lines 133b (see FIG. 21) of the third blades and connected fluid-communicatively with each third accelerating suction part. In this case, the third accelerating suction part 134 is constructed such that it externally surrounds the third incision part 123b. The third accelerating suction part 124 may be provided at an intermediate portion thereof with at least one or more third reinforced ribs 133d, if necessary, to form a plurality of third suction parts 134a, 134b and 134c. The front end 133e of the third peripheral wall part and the front end 133f of the third reinforced rib 133d of each second accelerating suction part 134 are formed in an acute shape like the cutting edge of a knife, which is called "a third edge-shaped front tip". The third edge-shaped front tips 133e and 133f act to minimize diffusion phenomenon of fluid occurring at its collision section and collision resistance when colliding against the fluid during its high-speed rotation, and suppress generation of cavitation. FIG. 22 is a perspective view illustrating a guide part of the inventive super high-speed fluid propulsion apparatus, and FIG. 23 is a cross-sectional view taken along the line H-H of FIG. 22; The guide part 23 includes a fourth hub 140 connected to the driving shaft 200 so that the driving shaft is rotatably supported by the fourth hub, a plurality of guide blades 142 arranged around the fourth hub in such a fashion as to be integrally formed with the fourth hub, a circular tube-type duct 141 coupled with the guide blades (142) in such a fashion that the tips of the guide blades are securely coupled to the inner peripheral surface of the circular tube-type duct, and a pair of brackets 143 mounted at one ends thereof to the outer peripheral surface of the circular tube-type duct and fixed at the other ends thereof to a ship body. The brackets serve to prevent the front propulsion unit 100, the middle propulsion unit 101 and the rear propulsion unit 102 from being shaken during the rotation of the propulsion units. To the rear end of the third shaft 230 is fixed a streamlined cap 231 (see FIG. 2) . FIGs. 24 and 26 are vertical cross-sectional view illustrating a crown-shaped reverse means of the inventive super high-speed fluid propulsion apparatus in non- activated and activated states, FIGs. 25 and 27 are partially enlarged views of FIGs. 24 and 26, FIG. 28 is a perspective view illustrating a collapsible plate of the crown-shaped reverse means, and FIG. 29 is a cross- sectional view taken along the line I-I of FIG. 28. As shown in the drawings, to the rear side of the guide part 23 may be coupled a reverser 24 for creating an inverse thrust or propulsive force, if necessary. The reverser 24 is constructed such that a crown-shaped reverse means 151 is foldably coupled to a guide tube 50 fixed to the rear portion of the guide part 23 by means of a drive means. The crown-shaped reverse means 151 consists of a plurality of fan-shaped collapsible plates 153, and the drive means 152 is constructed such that a plurality of cylinders 154 are fixed to the outer peripheral surface of the guide tube 150, a dual plunger 155 and 156 is connected to each cylinder 154 in such a manner that a first plunger 155 is fixed at one end thereof to a first connecting member 155a and connected at the other end thereof to each cylinder, and a second plunger 156 is connected at one end thereof to the first connecting member 155a while passing through the first connecting member 155a and is connected at the other end thereof to a second connecting member 156a while passing through the second connecting member 156a, and first and second connecting levers 157 and 158 are hingeably coupled at one ends thereof to the first and second connecting member 155a and 156a, respectively, and coupled at the other ends thereof to the fan-shaped collapsible plate 153. In this case, the first and second connecting members 155a and 156a are coupled with the guide tube in such a manner as to slidably move along the outer peripheral surface of the guide tube in a longitudinal direction thereof. A cylindrical protection cover 160 is disposed outside both the circular tube-type duct 141 of the guide part 23 and the cylinders 154. The cylindrical protection cover 160 has two fixing recesses 161 formed on at opposite side ends of the outer peripheral surface thereof, so that it is fixed in such a manner that a support at the lower end of each bracket 143 of the guide part 23 is fit into the fixing recess 161 as shown in FIG. 1. As shown in FIG. 1, in the case where the inventive fluid propulsion apparatus is coupled to a ship, it may be installed inside the ship body 1, but not outside the ship body as shown in FIG. 55. That is, the inventive fluid propulsion apparatus can be used in the same mode as a conventional water jet-type fluid propulsion apparatus. In the case where the inventive fluid propulsion apparatus is installed inside the ship body, a fluid suction opening 500 formed at the bottom the sip body is provided with a grid 501 for interrupting the introduction of foreign substances, so that upon the introduction of sucked sea water into the ship body, fishing nets or foreign substances, etc., are prevented from flowing inside the fluid propulsion apparatus. The operation of the inventive fluid propulsion apparatus having the construction of the first embodiment as described above will now be explained hereinafter. First, the driving shaft 200 is operated in the order of the first shaft 210, the second shaft 220 and the third shaft 230 arranged in series in such a fashion that the rear shaft rotates at a higher speed than that the front shaft. That is, since the front propulsion unit 100 of the front propulsion part 20 fixed to the first shaft 210 must suck in a large amount of good quality fluid to be discharged backward without cavitation, it rotates at a relatively lower speed as compared to other propulsion units . Also, the second shaft 220 rotates at a more highly accelerated - speed by a predetermined ratio (for example, over 30%) than that . of the first shaft 210. This is aimed to acceleratingly continue to feed introduced fluid backward via a plurality of middle propulsion units 101 constituting the middle propulsion part 21. • The- rear propulsion unit 102 of the rear propulsion part 22 fixed to the third shaft 230 serves to powerfully ■ push' the fluid backward ultimately, in which case, the ■ third shaft 230 rotates at a more highly accelerated speed ■by a certain ratio (for example, over 30%) than' that of the second shaft 220, so that the fluid can be powerfully pushed backward in a water jet state. ■ As described above,' when the first, second and third shafts 210, 220 and 230 of the driving shaft 200 rotate at different speeds, the first propeller 112 of the front propulsion unit 100 sucks in a • large amount of fluid flowing in front of the outside of the front propulsion unit and pushes the fluid backward while rotating. That is, the front propulsion unit 100 of the super high-speed fluid propulsion apparatus according to the present invention functions to suck in and acceleratingly feed as much fluid as possible from the front to the back. Thus, the front propulsion unit 100 is maintained at a relatively stable low rotational speed as compared to the second and third propulsion units having second and third accelerated fluid, making it possible to suck in and discharge a large amount of fluid without any generation of cavitation. Further, the first blades 111 of the front propulsion unit 100 is formed in a convex shape having a larger area in order to secure the maximum amount of fluid. In this manner, when the first propeller 112 of the first propulsion unit 100 rotates to suck a large quantity of fluid therein by means of the first blades 111, a large amount of fluid also starts to be sucked into the first propulsion unit 100 with high pressure through the first accelerating suction parts 114 formed on the outer peripheral surface of the first duct 113 rotating simultaneously with the first propeller. In this case, the fluid introduced into the first propulsion unit 100 by the first propeller collides against and is reflected at depressed surfaces inside the first blades 111 formed in a convex shape, at which time most of fluid flows inward from the first blades depending on a gradient of the inner curved surfaces of the first blades and is pushed backward. But some of the sucked fluid collides against a region adjacent to the front tip of each first blade and then tends to be diffused to the outside of the first blade. In order to prevent such a diffusion phenomenon of fluid, as shown in FIGs. 5 and 7, each blade is formed with a first diffusion-preventing part 113f configured such that the front tip of each first blade 111 is slightly bent by a certain width inward from a curved surface of the blade 111. Owing to this configuration, fluid colliding against the radially inward surface of a blade portion adjacent to the front tip of each first blade is converged toward the inner surface of the blade, but not diffused to the outside of the blade. Also, as shown in FIGs. 5 and 9, some of the fluid reflected at the inner surface of the blade flows back toward the outside through the slant top surface of a first rib 113c. Accordingly, in order to prevent such a back flow phenomenon of the fluid, the first duct 113 is formed at an upper surface thereof with a plurality of second diffusion- preventing parts 113i, so that fluid sucked to the inner surface of the blade is partially prevented from being diffused to the outside. Also the fluid flowing back toward the outside through the slant top surface of the first rib 113c is not diffused to the outside, but converged toward the inner surface of the blade by means of a force of fluid forcibly introduced into the first accelerating suction parts 114 toward the inside of the front propulsion unit 100 along the first duct 113 upon the high speed rotation of the first duct. In particular, as shown in FIG. 9, the, fluid flowing into the first accelerating suction parts 114 is smoothly induced into the first propulsion unit 100 along the inclined surfaces of the first rib 113 and the first reinforced rib 113d without any resistance. The flow of the induced fluid, as shown in FIGs. 9 and 10, is directed toward the rear of the first propulsion unit by means of first directional rudders 113e integrally formed at distal ends of the first rib 113c and the first reinforced rib 113d. After the above action has been completed, a large quantity of fluid sucked into the front propulsion unit 100 from the front joins the fluid introduced into the front propulsion unit through the first accelerating suction parts 114, and then is powerfully pushed toward the middle propulsion unit 101. Of course, at this time, the fluid is blocked by the inner wall of the first duct 113, and hence is injected toward the back of the front propulsion unit in a straight line form, but not diffused toward the lateral side of the front propulsion unit. As "'described above, according to the present invention, the front propulsion unit alone can sufficiently perform a function of a fluid propulsion apparatus. Accordingly, it is not necessary that the front propulsion unit 100 be implemented with it being coupled with the middle propulsion unit or the rear propulsion unit. Therefore, although the fluid propulsion apparatus of the present invention is implemented only with the front propulsion unit 100, it can produce a stronger thrust or propulsive force than a conventional screw-type propeller. In addition, for the middle propulsion unit 101 including the second propeller 122 having the second hub 120 and the plurality of blades 121, and the second duct 123, the middle propulsion unit 101 secondarily injects fluid sucked thereto from the front propulsion unit 100 with high pressure toward the rear propulsion unit 102 while the second blades rotate. To the secondarily injected fluid is added the fluid sucked into the middle propulsion unit 101 with high pressure through the second accelerating suction parts 124 formed on the outer peripheral surface of the second duct 123 during the high speed rotation of the second duct, and so the resultant fluid is more powerfully injected toward the rear propulsion unit, thereby obtaining a stronger output water. Namely, since the middle propulsion unit 101 rotates at a more highly accelerated speed by a predetermined ratio than that of the front propulsion unit 100, the second blades 121 also rotate proportionally at a higher speed than that of the first blades 111,. Accordingly, the middle propulsion unit 101 further secondarily accelerates the output fluid accelerated primarily in an interval of the front propulsion unit 100 with the second blades 121 of the middle propulsion unit 101, and, simultaneously to the secondarily accelerated output fluid is added the accelerated output fluid additionally obtained through the second accelerating suction parts 124 formed around the second duct 123, thereby producing a more powerful output fluid. Specially, when a plurality of middle propulsion units 101 are arranged in series like in the. first embodiment, a more powerfully accelerated output fluid can be produced. Further, for the rear propulsion unit 102 including the third propeller 132 having the third hub 130 and the plurality of blades 131, and the third duct 133, the rear propulsion unit 102 tertiarily injects fluid sucked thereto from the middle propulsion unit 101 with high pressure toward the back while the third blades rotate. Similarly, to the tertiarily injected fluid is added the fluid sucked into the third propulsion unit 101 with high pressure through the third accelerating suction parts 134 formed on the outer peripheral surface of the third duct 133 during the high speed rotation of the third duct, and so the resultant fluid is much more powerfully injected toward the back, thereby obtaining output water with a stronger injection power. That is, since the rear propulsion unit 102 also rotates at a more highly accelerated speed by a predetermined ratio than that of the middle propulsion unit 101, the third blades 131 also rotate proportionally at a higher speed than that of the second blades 121 of the middle propulsion unit. Accordingly, the rear propulsion unit 102 further tertiarily accelerates the output fluid accelerated secondarily in an interval of the middle propulsion unit 101 with the third blades 131 of the rear propulsion unit 102, and simultaneously to the tertiarily accelerated output fluid is added the accelerated output fluid additionally obtained through the, third accelerating suction parts 134 formed around the third duct 133, thereby producing a more powerful output fluid to be finally injected to the outside through the guide part 23. The front tips of the blades 111', 112 and 131 and the accelerating suction parts (14) of the respective propulsion units 100, 101 and 102, which are in close contact with fluid, are formed in an edge shape having a sharp acute angle. Since each propulsion unit of the present invention rotates at an super high speed, the front tip of each blade colliding against fluid during the rotation of the propulsion unit and the front tip of each accelerating suction part formed on the outer peripheral surface of the duct are also increased very significantly in motion velocity. Thus, when the front tips of each blade and each accelerating suction part collide against the fluid, they are applied with a great impact resistance as if they collided against a solid material. In this case, since the fluid is also applied with high collision pressure, it is diffused momentarily and cavitation phenomenon easily occurs around the fluid collision region of the blade and the accelerating suction part. For this reason, as mentioned above, ■ the respective front tips are formed in a sharp edge .shape, so that a collision area between the fluid and the blade is minimized, and accordingly, fluid collision resistance is minimized in spite of high speed rotation of the blade. Also the front tips act to suppress the generation of fluid diffusion and cavitation due to collision between each blade and fluid. In order • to implement the present invention, all the propellers may be fabricated using metals or synthetic resins such as FRP or the like, and the front, the middle and the, rear propulsion units may be used independently or cόmbinatively. Although the middle propulsion unit of the first • embodiment shown in the drawings has bee three in number, the number of the middle propulsion units can be increased or decreased. Also the number of blades of each propulsion unit may be increased or decreased, if necessary. Moreover, although there is a little difference in efficiency depending on the type of the hub, it may be modified in various forms. The driving shaft may be altered into a single shaft, a dual shaft, a triple shaft and the like, and may be applied by controlling its rotational speed. That is, an optimum rotation condition can be found by differently controlling the rotational speed of each shaft. In this embodiment, although there has been illustrated an example of the applied to a ship as a propulsion system, the present invention may be used as various pumps and ventilators.

In the above, the construction and operation of the super high-speed fluid propulsion apparatus according to the first embodiment of the present invention has been described. In case of the second to fifth embodiments which will be described below, only portions different from the first embodiment will be explained. Therefore, a portion for which a special description has been omitted should be construed as having the same construction and operation as those of the first embodiment. The most distinct characteristics in the configuration of the second to fifth embodiments of the present invention resides in that trumpet-shaped ducts are rotatably installed inside the inventive fluid propulsion apparatus. For this reason, when the propellers rotate to suck fluid into the front propulsion unit, the sucked fluid is forcibly pushed backward while passing through respective trumpet-shaped ducts. At this time, since each trumpet- shaped duct is gradually decreased in diameter as it goes from the front of the duct toward the back, the flow speed of fluid passing through the trumpet-shaped ducts is increased. The fluid flowing inside each trumpet-shaped duct being rotated is accelerated to a high speed over time, so that it repeatedly continues to join fluid introduced into the duct with high pressure through accelerating suction parts formed around the duct, thereby producing a more powerful thrust or propulsive force. Furthermore, the above operation is performed in such a fashion that fluid sucked into the propulsion unit repeatedly passes through a plurality of rotating trumpet- shaped ducts with them overlapped one another. So, as the fluid proceeds from the front of the propulsion unit to the back, output fluid causing a more powerful thrust is produced.

(Second embodiment) The construction of the fluid propulsion apparatus having rotational trumpet-shaped ducts of the second embodiment will now be schematically described hereinafter. The front propulsion unit includes a first propeller having a first hub fixedly connected to the first shaft and a plurality of first blades arranged around the first hub in such a fashion as to be integrally formed with the first hub, and a first trumpet-shaped duct interposed between the first blades while partitioning the inside of the first blades in such a fashion as to be disposed concentrically about the first hub and integrally formed with the first blades, wherein the first trumpet-shaped duct is decreased in diameter gradually as it goes from the front toward the back and the first trumpet-shaped duct has a plurality of first pocket-shaped accelerating suction parts 314 formed on the outer peripheral surface thereof in such a fashion as to be incised and opened circumferentially outwardly, the first accelerating suction parts each having a first suction part 314d formed therein. The middle propulsion unit includes a second propeller having a second hub fixedly connected to the driving shaft and a plurality of second blades arranged around the second hub in such a fashion as to be integrally formed with the second hub, a second front accelerating suction part having a plurality of second front wings each extending circumferentially outwardly from the front end of one side of each second blade, and a second front trumpet-shaped duct, interposed between the second front accelerating suction part while partitioning the inside of the second front accelerating suction part in such a fashion as to be disposed concentrically about the second hub and integrally formed with the second blades. At this time, the second front trumpet-shaped duct via which fluid is introduced is decreased in diameter gradually as it goes from the front toward the back. The middle propulsion unit ' includes a plurality of second rear accelerating suction part formed on the outer peripheral .surfaces thereof, the second rear accelerating suction parts each having a second rear pocket 324-2a formed in such a fashion as to be opened circumferentially outwardly from the second. The middle propulsion unit also includes a second rear trumpet-shaped duct interposed between the second rear accelerating suction parts while partitioning the inside of the second rear accelerating suction parts in such a fashion as to be disposed concentrically about the second hub. At this time, the second rear trumpet-shaped duct via which fluid is introduced is decreased in diameter gradually as it goes from the front toward the back. The second rear trumpet-shaped duct has a second suction part formed therein. The rear propulsion unit includes a third propeller having a third hub fixedly connected to the driving shaft and a plurality of third blades arranged around the second hub in such a fashion as to be integrally formed with the third hub, a third front accelerating suction part having a plurality of third front wings each extending circumferentially outwardly from the front end of one side of each third blade, and a third front trumpet-shaped duct interposed between the third front accelerating suction part while partitioning the inside of the third front accelerating suction part in such a fashion as to be disposed concentrically about the third hub and integrally formed with the third blades. At this time, the third front trumpet-shaped duct via which fluid is introduced is decreased in diameter gradually as it goes from the front toward the back. The rear propulsion unit includes a plurality of third rear accelerating suction parts formed on the outer peripheral surfaces thereof, the third rear accelerating suction parts each having a third rear pocket formed in such a fashion as to be opened circumferentially outwardly from the third propeller. The rear propulsion unit also includes a third rear trumpet-shaped duct interposed between the third rear accelerating suction parts while partitioning the inside of the third rear accelerating suction parts in such a fashion as to be disposed concentrically about the third hub. At this time, the third rear trumpet-shaped duct via which fluid is introduced is decreased in diameter gradually as it goes from the front toward the back. The third rear trumpet-shaped duct has a third suction part formed therein. And a streamlined tail part is formed at the rear end of the third shaft. As described above, according to the present invention, in the case where the front propulsion unit, the middle propulsion unit and the rear propulsion unit are coupled with one another, the trumpet-shaped ducts are arranged in a row at regular intervals in such a fashion that the front and the back of respective trumpet-shaped ducts are partially nested within one another. Thus, the fluid can be repeatedly accelerated in a multi-stage mode. The configuration of the second embodiment according to the present invention will be described in detail hereinafter with reference to the accompanying drawings. FIG. 30 is a cross-sectional side view illustrating a state in which the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention is applied to a ship, FIG. 31 is a vertical cross-sectional view of FIG. 30, FIG. 32 is an exploded perspective view illustrating essential parts of the super high-speed fluid propulsion apparatus of the second embodiment, FIG. 33 is an assembled perspective view of FIG. 32, and FIG. 34 is a partial cross-sectional perspective view of FIG. 33. As shown in the drawings, the propulsion units 100, 102 and 102 are coupled to a driving shaft 200 coupled to the rear end of a ship body and is adapted to rotate in response to rotation of the driving shaft. The propulsion units 100, 102 and 102 includes propellers 312, 322 and 332 having hubs 310, 320 and 330 fixedly connected to the driving shaft 200 and a plurality of blades 311, 321 an 331 arranged around each of the hubs so as to be integrally formed with each hub, respectively. Also, the propulsion units 100, 102 and 102 further include ducts 313, 323-1, 323-2, 333-1 and 333-2 provided at the outer side of the propellers 312, 322 and 332 in such a fashion as to be integrally formed with the propellers, and having a plurality of accelerating suction parts 314, 324-1, 324-2, 334-1 and 334-2 formed on the outer peripheral surfaces of the ducts so that fluid flowing around the propulsion units is sucked sideward into the propulsion units through the accelerating suction parts and is powerfully forcibly pushed toward the blades 311, 321 and 331. In this embodiment, the ducts 313, 323-1, 323-2, 333-1 and 333-2 is formed in a trumpet shape. The front portion of each trumpet-shaped duct is gradually decreased in diameter as it goes from the front toward the back. Similarly to the first embodiment, in the second embodiment of the present invention, the front propulsion unit 100, the front propulsion unit 101 and the rear propulsion unit 102 are coupled to the driving shaft 200. In this case, the propulsion units 100, 101 and 102 may be coupled to the driving shaft 200 in such a fashion that' only the front propulsion unit 100 is independently coupled to the driving shaft 200, the front propulsion unit 100 and the middle propulsion unit 101 are coupled to the driving shaft 200 with them coupled to each other, or the front propulsion unit 100 and the middle propulsion unit 101 are coupled to driving shaft 200 with them coupled to one another. Such coupling type may be optionally used depending on the need of a user. This will be determined according to use environment, the magnitude of driving power, the strength of required output, etc. Also, all the propulsion units 100, 101 and 102 may be coupled to one driving shaft 200, and as shown in FIG. 4, the propulsion units 100, 101 and 102 are independently coupled to a plurality of driving shafts 200, respectively. In addition, in the case where the driving shaft 200 an the propulsion units 100, 101 and 102 are installed at a ship, as shown in FIG. 30, they are mounted inside a housing 360 for preventing introduction of foreign substances. The housing 360 is provided with a grid 361 so that foreign substances are interrupted from being introduced into the propulsion units 100, 101 and 102. FIG. 35 is a perspective view illustrating a front propulsion unit of the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention, FIG. 36 is a side view illustrating the front propulsion unit of FIG. 35, and FIG. 37 is a cross- sectional view taken along the line A-A of FIG. 36; Now, the construction of the front propulsion unit according to the second embodiment of the present invention will be in detail described hereinafter with reference to FIGs. 35 to 37. Referring to the drawings, the front propulsion unit 100 includes a first propeller 312 having a first hub 310 fixedly connected to the driving shaft 200 and a plurality of first blades 311 arranged around the first hub 310 in such a fashion as to be integrally formed with the first hub, and a first trumpet-shaped duct 313 provided at the inside of the first propeller 312 in such a fashion as to be disposed concentrically about the first hub and integrally formed with the first blades, wherein the first trumpet-shaped duct is decreased in diameter gradually as it goes from the front toward the back and the first trumpet-shaped duct has a plurality of first pocket-shaped accelerating suction parts 314 formed on the outer peripheral surface thereof in such a fashion as to be incised and opened circumferentially outwardly, the first accelerating suction parts each having a first suction part 314d formed therein. The first blades 311 of the first propeller are coupled to a first hub 310 with it being formed in a spiral shape, and have a convex surface bulged circumferentially. The first trumpet-shaped duct 313 is interposed between the first blades 311 in such a fashion as to partition the inside of the first blades 311. At this time, the first trumpet-shaped duct 313 is arranged in a row at regular intervals together with a second trumpet-shaped duct 323 and a third trumpet-shaped duct 333 which will be described later in such a fashion that the front and the back of respective trumpet-shaped ducts are partially nested within one another. Thus, the fluid introduced into the ducts from the outside continues to repeatedly join the fluid flowing inside the ducts. Between each first accelerating suction part 314 and the first trumpet-shaped duct 313 is disposed at least one first reinforced rib 314b. In this case, the first reinforced rib 314b is at a certain angle bent at the front end thereof positioned at the inner side of the propulsion unit . ■ ' At this time, the top end of each first blade 311, the front ends of the first trumpet-shaped duct 313 and the first reinforced rib 314b which are exposed to the outside are formed in a sharp shape like the cutting edge of a knife, which is called "first edge-shaped front tips 311a and 314c". Such a first edge-shaped front tips 311a and 314c acts to minimize collision resistance with fluid to allow a large quantity of good fluid, i.e., fluid having no cavitation to be sucked into the front propulsion unit. The front end 313a of the first trumpet-shaped duct 313 is formed in a round shape, but not in an acute shape. The reason for this is why the front end 313a .of the first trumpet-shaped duct 313 does not severely collide with' fluid during the rotation of the duct. As shown in FIG. 31, the first trumpet-shaped duct 313 further includes a first buoyancy forming part 315 formed on the outer peripheral' surface of the lower portion , thereof. The first buoyancy forming part 315 consists of a first front guide plate 315a ' formed along the outer circumferential surface of the first trumpet-shaped duct 313 from a first coupling part 318 to the upper end of the first trumpet-shaped duct 313 in such a fashion as to be formed concavely in a uniform gradient, and a first side guide plate 315b extending from the first side guide plate 315a perpendicularly to the first front guide plate 315a, for connecting the first coupling part 318 and the lateral surface of the first accelerating suction part 314 to each other ( s ee FIG . 3 6 ) . Accordingly, the first front guide plate 315a and the first side guide plate 315b define a certain space intercepted from the outside in-between with the first accelerating suction part 314a and the first trumpet-shaped duct 313, so that buoyancy is created in the space. Referring back to FIG. 31, at the bottom of the front propulsion unit 100 is formed a first coupling part 318 which is formed with a predetermined groove for fitting the corresponding protrusion of the front end of the middle propulsion unit 101 or the rear propulsion unit 102 thereto so as to be coupled with the front end of the middle propulsion unit 101 or the rear propulsion unit 102. FIG. 38 is a perspective view illustrating a middle propulsion unit 101 of the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention, FIG. 39 is a side view illustrating the middle propulsion unit of FIG. 38, FIG. 40 is a cross- sectional perspective view taken along the line B-B of FIG. 39, FIG. 41 is a top plan view of FIG. 40, FIG. 42 is a cross-sectional top plan view taken along the line C-C of FIG. 39, and FIGs. 43 and 44 are perspective and partial side views illustrating second blades 321 of the inventive super high-speed fluid propulsion apparatus. Now, the construction of the middle propulsion unit according to the second embodiment of the present invention will be in detail described hereinafter with reference to FIGs. 38 to 44. Referring to the drawings, the middle propulsion unit 101 includes a second propeller 322 having a second hub 310 fixedly connected to the driving shaft 200 and a plurality of second blades 321 arranged around the second hub 320 in such a fashion as to be integrally formed with the second hub, and a second front accelerating suction part 324-1 having a plurality of second front wings 324-la each extending circumferentially outwardly from the front end of one side of each second blade 321. Also, the middle propulsion unit 101 further include a second front trumpet-shaped duct 323-1 provided at the inside of the second propeller 322 in such a fashion as to be disposed concentrically about the second hub and integrally formed with the second blades. At this time, the second trumpet-shaped duct 323-1 via which fluid is introduced is decreased in diameter gradually as it goes from the front toward the back. In addition, the middle propulsion unit 101 includes a second propeller 322 having a second hub 320 fixedly connected to the driving shaft 200 and a plurality of second blades 321 arranged around the second hub 320 in such a fashion as to be integrally formed with the second hub, and a second rear trumpet-shaped duct 323-2 disposed concentrically about the second hub, the second rear trumpet-shaped duct being decreased in diameter gradually as it goes from the front toward the back. In this case, the second rear trumpet-shaped duct 323-2 has a plurality of second rear accelerating suction parts 324-2 formed on the outer peripheral surface thereof, and each of the second rear accelerating suction parts is formed with a second rear pocket 324-2a by means of a second reinforced rib 324-2b and has a second suction part 324-2d formed therein. For reference, the second front trumpet-shaped duct 323-1 and the second rear trumpet-shaped duct 323-2 can be easily distinguished from each other in FIG. 31. In this case, the back end of the front propulsion unit 100 and the front end of the middle propulsion unit 101 are coupled with each other. The second blades 321 are formed integrally with the middle propulsion unit 101. As shown in FIG'S. 43 and 44, the second blades 321 are integrally coupled with the second hub 320 with it being formed in a spiral shape. A second front wing 324-la is integrally formed with the front tip of each second blade 321. The front ends of second front wings 324-la are oriented toward the rotational direction of the middle propulsion unit 101. FIG. 44 is a perspective view showing a state in which only one blade is coupled to the second hub 320 for providing an easy understanding of the construction of the second blades 321. In an actual implementation, such a second blade 321 as shown in FIG. 43 is arranged in plural on the outer peripheral surface of the second hub at regular intervals . A second front reinforced rib 324-lc is interposed between the plurality of second front wings 324-la in such a fashion as to be fittingly intersect the center of each second front wing perpendicularly to the plane of the second blade. The second front reinforced rib 324-lc takes an annular ring shape with a certain width along a circumferential direction of the second front wings 324-la. The front end of the second front wing 324-la is circumferentially bent at a predetermined angle so that the flow of fluid introduced into the second front wings 324-la can be guided toward the inside of the second and third trumpet-shaped ducts. Between two adjacent second front wings 324-la are slantIy arranged one or more second sub-wings along a circumferential direction of the second front reinforced rib in parallel with the second front wings324-la. At this time, the second front sub-sings 324-lb are coupled to only the second front reinforced rib 324-lc, but not coupled integrally to the second blades 321. Further, as shown in FIG. 40, in the second embodiment, two second front sub-wings 324-lb are disposed between two adjacent second front wings, respectively, with them fit on the second' front reinforced rib 324-lc. The number of second front sub-wings may be changed depending on the dimension of the entire propulsion apparatus, but are not limited. For example, in case of a larger-sized propulsion apparatus, more than three second front sub-wings 324-lb may be arranged between two adjacent second front wings 324-la in order to maximally suck in fluid. On the other hand, in case of a smaller-sized propulsion apparatus, only one second front sub-wing may be arranged or not between two adjacent second front wings 324-la. At the lower end portion of the middle propulsion unit 101 are provided a second rear trumpet-shaped duct 323-2, second rear accelerating suction parts 324-2, second buoyancy forming part 325, second suction parts 324-2d, etc., in which case these constitutional elements are coupled with each other in the similar manner to the front propulsion unit 100. That is, the second rear accelerating suction parts 324-2 are formed around the second rear trumpet-shaped duct 323-2, and the second buoyancy forming part 325 is formed between the lower end of the second rear accelerating suction parts 324-2 and the second rear trumpet-shaped duct 323-2 (see FIG. 31) . The second buoyancy forming part 325 consists of a second front guide plate 325a and a second side guide plate 325b, and has the same configuration and arrangement as that of the first buoyancy forming part 315. At the front end of the middle propulsion unit 101 are formed a second-1 coupling part 328a for coupling with the rear end of the front propulsion unit 100, and at the rear end of the middle propulsion unit 101 are formed a second-2 coupling part 328b for coupling with the front end of the rear propulsion unit 102. At the rear surface of the second-2 coupling part 328a is formed a second reflective plate 324-e having a uniform gradient (see FIGs. 31 and 34) . The externally exposed front end of second blades 321, the second front accelerating suction parts 324-1 and the second rear accelerating suction parts 324-2 is formed in an acute shape like the cutting edge of a knife which is called a second edge-shaped front tip 321a, 324-ld and 324- 2d. FIG. 45 is a cross-sectional view illustrating a rear propulsion unit of the super high-speed fluid propulsion apparatus according to the second embodiment of the present invention. Now, the construction of the rear propulsion unit according to the second embodiment of the present invention will be in detail described hereinafter with reference to FIGs. 32 to 34 and 45. Referring to the drawings, the rear propulsion unit 102 includes a third propeller 332 having a third hub 330 fixedly connected to the driving shaft 200 and a plurality of third blades 331 arranged around the second hub 310 in such a fashion as to be integrally formed with the third hub, a third front accelerating suction part 334-1 having a plurality of third front wings 334-la each extending circumferentially outwardly from the front end of one side of each third blade 331, and a third front trumpet-shaped duct 333-1 provided at the inside of the third propeller 332 in such a fashion as to be disposed concentrically about the second hub and integrally formed with the third blades, the third front trumpet-shaped duct being decreased in diameter gradually as it goes from the front toward the back. In addition, the rear propulsion unit 102 includes a third propeller 332 having a third hub 330 fixedly connected to the driving shaft 200 and a plurality of third blades 321 arranged around the third hub 330 in such a fashion as to be integrally formed with the third hub, and a third rear trumpet-shaped duct 333-2 disposed concentrically about the third hub and integrally formed with the third blades, the third rear trumpet-shaped duct being decreased in diameter gradually as it goes from the front toward the back. In this case, the third rear trumpet-shaped duct 333-2 has a plurality of third rear accelerating suction parts 334-2 formed on the outer peripheral surface thereof, and each of the third rear accelerating suction parts is formed with a third rear pocket 334-2a by means of a third reinforced rib 334-2b and has a third suction part 334-2d formed therein. The entire construction and arrangement of the rear propulsion unit 102 is similar to that of the middle propulsion unit 101 except the following aspects: The rear propulsion unit 102 is a propulsion unit disposed at the rearmost position of propulsion units of the present invention. At the back of the rear propulsion unit 102 is formed a discharge part 316 so that fluid fed from the front propulsion unit 100 can be discharged to the outside. The rear portion of the discharge part 316 is formed in a tapered tubular shape of which diameter is decreased gradually as it goes toward the back. Also, to the distal end of the third hub 330 is coupled a streamline tail part 317 by a fastening means. The streamline tail part 317 takes an oval shape so that even when it is placed in fluid being injected, a swirl or vortex of fluid or cavitation is not created at the rear portion thereof. The streamline tail part 317 may be disposed inside the rear propulsion unit 102 or partially disposed outside the rear propulsion unit 102. The size and shape of the streamline tail part 317 may be appropriately modified, depending on the size or use condition of the entire apparatus by a designer. The operation of the inventive fluid propulsion apparatus having the construction of the second embodiment as described above will now be explained hereinafter. First, when the driving shaft 200 rotates, the first, second and third blades 311, 321 and 331 coupled with the driving shaft 200 rotate simultaneously. Also, the trumpet- shaped ducts 313, 323-1, 323-2, 333-1 and 333-2, which are coupled with the first, second and third blades 311, 321 and 331, also rotate simultaneously in response to the rotation of the blades. Accordingly, fluid flowing around the blades 311, 321 and 331 is introduced into the trumpet- shaped ducts 313, 323-1, 323-2, 333-1 and 333-2. At this time, the flow speed of the introduced fluid is accelerated increasingly while passing through the inside of the trumpet-shaped ducts due to the sectional structure of the trumpet-shaped duct of which diameter becomes decreased gradually as it goes from the front toward the back. In this case, a plurality of accelerating suction parts 343, 324-1, 324-2, 334-1 and 334-2 formed around each of the trumpet-shaped ducts 313, 323-1, 323-2, 333-1 and 333-2 rotate simultaneously with the respective trumpet- shaped ducts 313, 323-1, 323-2, 333-1 and 333-2. Thus, fluid moving past the respective , propulsion . units is forcibly sucked into the accelerating suction parts 343, 324-1, 324-2, 334-1 and 334-2 of the propulsion units with higher pressure. In this manner, the fluid introduced into the respective propulsion units via the accelerating suction parts 343, 324-1, 324-2, 334-1 and 334-2 is guided toward the respective trumpet-shaped ducts 313, 323-1, 323-2, 333- 1 and 333-2, and then joins fluid passing through the inside of the propulsion units through the blades 311, 321 and 331, thereby further increasing the flow rate of fluid flowing inside the propulsion units. The flow rate of the fluid inside the propulsion units is increased as much fluid as- is sucked in by the accelerating suction parts, so that the flow speed of fluid passing through the trumpet- shaped duct positioned at the rear portion of each propulsion unit is further accelerated. Moreover, the buoyancy forming parts formed around each of the trumpet-shaped ducts 313, 323-1, 323-2, 333-1 and 333-2 internally define hollow spaces so that the inventive fluid propulsion apparatus is prevented from being downward deflected due to its own weight. That is, the hollow spaces of the buoyancy forming parts create buoyancy that the inventive fluid propulsion apparatus receives from the fluid. These buoyancy forming parts allow the force of gravity exerted downward by the fluid propulsion apparatus to be offset with the force of buoyancy exerted upward by the fluid propulsion apparatus, thereby exhibiting the same effect as reducing the weight of the fluid propulsion apparatus as a whole. The entire flow of fluid in the inventive fluid propulsion apparatus of the second embodiment will now be described hereinafter with reference to FIG. 31. First, fluid introduced into the first blade 311 of the front propulsion unit 100 is sucked into the middle propulsion unit 101 while rotating in an opposite direction to the rotating direction of the front propulsion unit. At the same time, fluid is also introduced into the front propulsion unit 100 through the first accelerating suction parts 314, and then joins the fluid introduced into the first blade 311. Thus, the subsequently joined fluid increase the amount of fluid inside the first trumpet- shaped duct 313, to thereby accelerate the flow speed of fluid at an outlet port side of the first trumpet-shaped duct having a smaller diameter than an inlet port thereof so as to be fed to the middle propulsion unit 101. As such, the fluid discharged from the front propulsion unit 100 is sucked into the middle propulsion unit 101 through the second blades 321 of the middle propulsion unit 101. The middle propulsion unit 101 includes the second trumpet-shaped ducts 323-1 and 323-2 such as the first trumpet-shaped duct 313 of the front propulsion unit 100, and thus the fluid sucked into the middle propulsion unit 101 acceleratingly flows inside the middle propulsion unit 101 while passing through smaller- diameter outlet ports of the second trumpet-shaped ducts. In this case, the middle propulsion unit 101 includes the second accelerating suction parts 324-1 and 324-2 formed on the outer peripheral surface thereof so that fluid flowing around the middle propulsion unit 101 can be additionally sucked into the second trumpet-shaped ducts therethrough. At this time, the accelerating suction part positioned at the front side of the middle propulsion unit 101 is called "a second front accelerating suction part 324-1", and the accelerating suction part positioned at the rear side of the middle propulsion unit 101 is called "a second rear accelerating suction part 324-2". The fluid sucked into the middle propulsion unit 101 through the second front wings 324-la and the second front sub-wings 324-lb of the second front accelerating suction part 324-1 collides against the second reflective plate 324-lc positioned at the back of the second-1 coupling part 328a, flows along a curved outer peripheral surface of the second front trumpet-shaped duct 323-1, and passes through a narrower fluid channel formed between the outer peripheral surface of the second front trumpet-shaped duct 323-1 and the inner peripheral surface of the second rear trumpet-shaped duct 323-2, so that the flow speed of the fluid is also accelerated. This accelerated fluid joins the fluid which is sucked into the middle propulsion unit 101 via the second blades 321 from the front propulsion unit 100 and accelerated while passing through the second front trumpet-shaped duct 323-1. After undergoing such a process, the resultant fluid which has passed through the middle propulsion unit 101 flows further acceleratingly at a higher speed. In addition, fluid is sucked into the middle propulsion unit 101 through the second rear accelerating suction part 324-2, i.e., the second suction part 324-2d formed inside the second rear accelerating suction part 324-2, and then additionally joins a mixture of the fluid introduced into the second front trumpet-shaped duct from the front propulsion unit 100 and the fluid sucked into the second rear trumpet-shaped duct from the second front accelerating suction part 324-1, leading to an increase in the amount of the fluid within the middle propulsion unit 101 to thereby further accelerate the flow speed of the fluid passing through the second rear trumpet-shaped duct 323-2. In this manner, the fluid introduced into the middle propulsion unit 101 from the front propulsion unit 100 is further accelerated with the aid of the fluid additionally introduced into the middle propulsion unit 101 from the both second accelerating suction parts 324-1 and 324-2, and then flows toward the rear propulsion unit 102. The fluid flowed into the rear propulsion unit 102 is further accelerated by the same operation as that of the middle propulsion unit 101. The discharge part 315 is formed at the back end of the rear propulsion unit 102 so that the resultant accelerated fluid is discharged to the outside, thereby creating a thrust or propulsive force. The rear portion of the discharge part 316 is formed in a tapered tubular shape of which diameter is decreased gradually as it goes toward the back so that swirl or vortex is prevented from occurring at the rear end portion of the discharge part 316. Such swirl refers to the flow of fluid involving whirling movements having a certain uniform magnitude and direction, which acts to obstruct the flow of fluid normally moving past an object. Thus, it is very important to interrupt such vortex formation so as to prevent degradation in a thrust or propulsive force. Moreover, to the lower end of the third hub 330 is mounted a streamlined tail part 317 as another means for prevention of vortex. The streamlined tail part 317 is aimed to prevent both vortex and cavitation from occurring at the rear end . of the third hub 330. If the streamlined tail part 317 is attached to the rear end of the third hub 330, then generation of ■ swirl or cavitation is minimized, thereby making it possible for fluid to smoothly flow at high speed and a high pressure. In addition, in the second embodiment, the streamlined tail part 317 is coupled to one driving shaft, but may be coupled to a multiple shaft as described in embodiment. At this time, it is possible to differently control the rotational speed of the respective front propulsion unit 100, middle propulsion unit 101 and rear propulsion unit 102. If the fluid propulsion apparatus is driven in' such a 'fashion that the rotational speed of propulsion units is gradually increased as it goes from the front toward the back, it is possible to easily produce a higher output. Further, similarly to the first embodiment, in the second embodiment, the front tips of the blades, the trumpet-shaped ducts and accelerating suction parts are formed in a sharp shape like the cutting edge of a knife so as to minimize friction resistance against fluid flow due to a high-speed rotation of the propulsion units, so that a large quantity of good fluid can be sucked in or discharged with a smaller driving force, thereby creating a more powerful thrust. The fluid propulsion apparatus according to the second embodiment of the present invention is installed at the rear end of a ship to be exposed to the outside so as to be used as a propulsion means, and may be installed inside the ship so that it can be used in the same mode as that of a conventional water-jet type propulsion system. Also, the inventive fluid propulsion apparatus may be installed in the air or at a place where oil or the like is filled so that it can be used as a hydraulic, oil hydraulic or pneumatic pump.

(Third Embodiment) The second embodiment of the present invention has been described in the above, and the construction of the third embodiment as a modification of the second embodiment will now be described hereinafter with reference to FIGs. 47 and 48. The fluid propulsion apparatus of the third embodiment of the present invention includes a front propulsion unit 100, a middle propulsion unit 101 and a rear propulsion unit 102, or a front propulsion unit 100 and a rear propulsion unit 102. Here, the front propulsion unit 100 of the third embodiment has the same configuration as that of the second embodiment, but the middle and rear propulsion units have a different configuration from that of the second embodiment. The middle propulsion unit 101 and the rear propulsion unit 102 of the third embodiment has nearly identical to each other in terms of a basic configuration except that the rear propulsion unit 102 has a discharge part 316 formed at the rear side thereof. The middle propulsion unit 101 will be omitted in the third embodiment, and the coupling of the rear propulsion unit 102 to the front propulsion unit 101 will be explained hereinafter. FIG. 47 is a cross-sectional view illustrating the super high-speed fluid propulsion apparatus according to the third embodiment of the present invention, and FIG. 48 is a perspective view illustrating the super high-speed fluid propulsion apparatus according to the third embodiment of the present invention, which includes the front propulsion unit 100 and the rear propulsion unit 102. In FIGs. 47 and 48, the front propulsion unit 100 will not be described since it is identical to that of the second embodiment, and only the rear propulsion unit 102 will be described, hereinafter. The rear propulsion unit 102 of the third embodiment is basically configured in such a fashion that the rear portion including the second rear accelerating suction part 324-2 of the middle propulsion unit 101 is continuously coupled with the rear portion including the third rear accelerating suction part 334-2 of the rear propulsion unit 102. More specifically, the rear propulsion unit 102 of the third- embodiment includes a third propeller 332 having a third hub 330 fixedly connected to the driving shaft 200 and a plurality of third blades 331 arranged around the third hub 330 in such a fashion as to be integrally formed with the third hub, and a third rear trumpet-shaped duct 333-2 disposed concentrically about the third hub and integrally formed with the third blades, the third rear trumpet-shaped duct being decreased in diameter gradually as it goes from the front toward the back. In this case, the third rear trumpet-shaped duct 333-2 has a plurality of third rear accelerating suction parts 334-2 formed on the outer peripheral surface thereof, and each of the third rear accelerating suction parts is . formed with a third rear pocket 334-2a by means of a third reinforced rib 334-2b and has a third' suction part 334-2d formed therein. The operation of the inventive fluid propulsion apparatus having the construction of the third embodiment as described above will now be.explained hereinafter. Fluid discharged from the' front propulsion unit 100 is introduced into the rear propulsion unit 102, and acceleratingly flows inside the third rear trumpet-shaped ■ duct 333-2 of the rear propulsion 'unit 102. In addition, fluid introduced into the rear propulsion unit 102 through the third rear accelerating suction parts 334-2 with a high pressure joins the fluid discharged from the front propulsion unit 100 and acceleratingly passing through the third rear trumpet-shaped ducf 333-2 of the rear propulsion unit 102. Such operation is the same' as that of the second embodiment in which fluid introduced into the rear propulsion unit 102 through the third rear accelerating. suction parts 334-2 with a high pressure joins a mixture of the fluid discharged from the third front trumpet-shaped duct 333-1 and the fluid introduced into the third rear trumpet-shaped duct 333-2 through the third front accelerating suction parts 334-1. Accordingly, in the third embodiment, the fluid sucked into the rear propulsion unit 102 through the third rear accelerating suction parts 334-2 serves to increase the■ amount of fluid passing through the inside of the third rear trumpet-shaped duct 333-2, thereby further accelerating the flow speed of the fluid discharged from a narrower outlet of the third rear ' trumpet-shaped duct 333-2 and injected to the outside, which creates a more powerful- thrust.

(Fourth Embodiment) The construction of the inventive' fluid propulsion apparatus of the fourth embodiment will- now be described hereinafter with reference to FIGs. 49 to 52. In ,FIGs. 49 to 52, only the rear propulsion unit 102 applied to the fourth embodiment is shown. The fluid propulsion apparatus of the fourth embodiment is configured in such a fashion that the front propulsion unit 100 used in the first and second embodiments is coupled to the rear propulsion unit 100 shown in FIGs. 49 to 52, or to the rear propulsion - unit 100 shown in FIGs. 49 to, 52 are coupled the front propulsion unit 100 used in the first and second embodiments and the middle propulsion unit 101 used in the first and third embodiments. In addition, the construction of the rear propulsion unit 101 of the fourth embodiment shown in FIGs. 49 to 52 may be employed as that of the middle propulsion unit 101 if the discharge part 316 formed at the rear end of the rear propulsion unit 101 is excluded. The construction of the rear propulsion unit of the fourth embodiment will now be described hereinafter with reference to FIGs. 49 to 52. FIG. 49 is a perspective view illustrating a rear propulsion unit of the super high-speed fluid propulsion apparatus according to the fourth embodiment of the present invention, FIG. 50 is a cross-sectional perspective view of FIG. 49, FIG. 51 is a cross-sectional view of FIG. 49, and FIG. 52 is a cross-sectional view illustrating a modified embodiment of FIG. 51. As shown in FIG. 50, the rear propulsion unit 102 of the fourth embodiment includes a third hub 330 fixedly connected to the driving shaft 200, a plurality of third front trumpet-shaped ducts 333-1 each disposed concentrically about the third hub, the third front trumpet-shaped duct being decreased in diameter gradually as it goes from the front toward the back, a plurality of third front accelerating suction parts 334-1 integrally formed on the outer peripheral surfaces of the third front trumpet-shaped ducts 333-1, and streamlined blades 350 for fixing the third front trumpet-shaped duct 333-1 and the third front accelerating suction parts 334-1 to the third hub 320. Each of the third front accelerating suction parts 334-1 has a third front wing 334-la having an opened surface oriented toward the same direction as the rotational direction of the third hub 330 and a plurality of third front reinforced ribs 334-lb formed on the third front wing 334-la in such a fashion as to be spaced apart from one another at regular intervals. The third front wings 334-la are longitudinally arranged on the outer peripheral surface of the third front trumpet-shaped duct 333-1 in such a fashion as to be spaced apart from one another at regular intervals. Also, the plurality of third front reinforced ribs 334-lb are interposed between two adjacent third front wings 334-la, respectively, in such a fashion as to be disposed perpendicularly to the plane of third front wings. In this case, the ends of the third front reinforced ribs 334-lb, which is directed inward of the rear propulsion unit, are partially bent toward the third hub. The third front trumpet-shaped duct 333-1 includes a plurality of fluid reflective plates 333a formed on the outer peripheral surface thereof in such fashion as to be integrally formed with the third front wings 334-la and disposed between two adjacent the third front reinforced ribs 334-lb, thereby achieving improved propulsion efficiency. The streamlined blades 350 have a streamlined, airfoil-type or ogive-type shape in cross section and are inclined at a certain angle. In addition, the third front trumpet-shaped duct 331-1, as shown in FIG. 50, is plurally arranged in a row within the rear propulsion unit 102 at regular intervals in such a fashion that the front and the back of respective third trumpet-shaped ducts are partially nested within one another. In FIG. 51, the fluid reflective plates 333a are omitted in the construction of the rear propulsion unit 102 of the fourth embodiment. Like this, when the fluid reflective plates 333a are excluded, the distal ends of the third front trumpet-shaped ducts 333-1 is fit into the third front wings 334-la in such a fashion as to be arranged perpendicularly to the third front wings 334-la. The operation of the inventive fluid propulsion apparatus having the construction of. the fourth embodiment as described above will now be explained hereinafter. As the driving shaft rotates, fluid sucked into the front propulsion unit 100 not shown is introduced into the rear propulsion unit 102. Then, the fluid introduced into the rear propulsion unit 102 passes through the third front trumpet-shaped ducts 333-1 so that the flow speed of the fluid flowing inside the third front trumpet-shaped ducts 333-1 is increased. . Also, when the rear propulsion unit 102 rotates at a high speed, fluid moving past the rear propulsion unit is introduced into spaces defined between the third front- wings 334-la of the third front accelerating suction parts 334-1 at a high pressure. At this time, the introduced fluid is branched off to the right and left sides with respect to each third front reinforced rib 334-lb. Some of the branched fluid collides against the fluid reflective plates 333a and then is directed toward the back so that it is introduced into the third front trumpet- shaped ducts 333-1, whereas the others of the branched fluid is introduced into spaces defined between the third front wings 334-la and the next fluid reflective plates 333a along the rear surface of the third front reinforced ribs 334-lb. In this manner, the fluid introduced into the third front trumpet-shaped ducts 333-1 through the third front accelerating suction parts 334-1 joins the fluid sucked into the third front trumpet-shaped ducts 333-1 of the rear propulsion unit 102 from the front propulsion unit 100, so that the flow amount of the fluid inside the third front trumpet-shaped ducts 333-1 is increased and the flow speed of the fluid is further accelerated while continuing to pass through narrower outlets of the third front trumpet- shaped ducts 333-1. Moreover, in the fourth embodiment, the third front trumpet-shaped ducts 333-1 are fixed to the third hub 330 by means of the streamlined blades 350 positioned at the front and back of the rear propulsion unit 102. The streamlined blades 350 also serves to backward push fluid introduced into the rear propulsion unit 102 through the' airfoil-type shaped cross section of the streamlined blades 350 while rotating besides the above-mentioned function. Resultantly, the streamlined blades is made slant relative to the advance direction of fluid like a general propeller, so that a thrust or propulsive force is produced due to a difference in pressure of fluid moving past the streamlined blades 350 in response to the rotation of the streamlined blades 350. As described above, the streamlined blades 350 is not disposed only at the front and the back of the rear the rear propulsion unit 102, but may be additionally provided inside the rear propulsion unit 102 depending on the property, speed and pressure of the flowing fluid. In case of the latter, it is possible to enhance a thrust or propulsive force of the fluid and increase the structural strength of the rear propulsion unit 102. The resultant fluid discharged from the rear propulsion unit 102 through the above operation passes through the discharge part 316 and the streamlined tail part 317, which is the same as in the second embodiment as described above. The blades of the middle propulsion unit 101 and the rear propulsion unit 102 of the second and third embodiments is configured in such a fashion as to be coupled to the second and third hubs inside the propulsion units with it being formed in a spiral shape, but may be configured in such a fashion as to be modified into a streamlined, airfoil-type shape in cross section similarly to the fourth embodiment. In the arrangement of the rear propulsion unit 102 of the fourth embodiment shown in FIG. 52, even when the fluid reflective plates 333a is excluded, the basic operation and working effect of the rear propulsion unit 102 is the same as that of the fourth embodiment. In this case, however, the fluid introduced into the third front trumpet-shaped ducts through the third front accelerating suction parts does not collide against the fluid reflective plates 333a to be directed toward the front trumpet-shaped ducts since the fluid reflective plates 333a are omitted, but can be introduced into the third trumpet-shaped ducts 331-1 along the outer peripheral surfaces of the third trumpet-shaped ducts smoothly curved from the distal ends of the third trumpet-shaped ducts. In this manner, if the fluid reflective plates 333a is omitted, the distal ends of the third front trumpet-shaped ducts 333-1 is fit into the third front wings 334-la in such a fashion as to be arranged perpendicularly to the third front wings 334-la.

(Fifth Embodiment) The construction of the inventive fluid propulsion apparatus of the fifth embodiment will now be described hereinafter with reference to FIG. 53. As shown in FIG. 53, the fluid propulsion apparatus includes a driving shaft 200 installed at the rear portion or at the inside of a ship, and a propulsion unit 2 coupled to the driving shaft 200 and adapted to rotate in response to rotation of the driving shaft. The propulsion unit 2 includes a plurality of fourth trumpet-shaped ducts 433-1 each longitudinally disposed in the inside center of the propulsion unit in such a fashion as to be decreased in diameter gradually as it goes from the front toward the back, and a plurality of fourth accelerating suction parts 434-1 each having a fourth wing 434-la integrally formed on the outer peripheral surfaces of the fourth trumpet-shaped ducts 433-1. At least one or more fourth reinforced ribs 434-lb are formed inside the fourth accelerating suction part 434-1 in such a fashion as to intersect the fourth accelerating suction part 434-1. Each of the fourth accelerating suction parts 434-1 has a fourth wing 434-la having an opened surface oriented toward the same direction as the rotational direction of the driving shaft 200 and a plurality of fourth reinforced ribs 434-lb formed on the fourth wing 434-la in such a fashion as to be spaced apart from one another at regular intervals. The fourth wings 434-la are longitudinally arranged on the outer peripheral surface of the fourth trumpet-shaped duct 433-1 in such a fashion as to be spaced apart from one another at regular intervals. Also, the plurality of fourth reinforced ribs 434-lb are interposed between two adjacent fourth wings 434-la, respectively, in such a fashion as to be disposed perpendicularly to the planes of fourth wings. In this case, the ends of the fourth reinforced ribs 434-lb, which is directed inward of the propulsion unit, are partially bent toward the center of the fourth trumpet-shaped duct 433-1. The fourth front trumpet-shaped duct 433-1 includes a plurality of fluid reflective plates 433a formed on the outer peripheral surface thereof in such fashion as to be integrally formed with the fourth wings 434-la and disposed between two adjacent the fourth reinforced ribs 334-lb, thereby achieving improved propulsion efficiency. Also, at the front of the propulsion unit 2 is provided a fourth coupling part 430 coupled with the driving shaft 200. The fourth coupling part 430 is formed at the rear surface thereof with a fourth reflective plate 431 inclined at a certain angle. At this time, the outer ■ contour of the fourth coupling part 430 assumes a conical shape and the driving shaft 200 is fit into the center of the fourth coupling part 430. Here, the outer contour of the fourth coupling part 430 is not limited to a specific one, but will be possible if whatever contour allows the propulsion unit 2 and the driving shat 200 to be coupled to each other. In addition, a fourth discharge part 416 is formed at the rear end of the last fourth trumpet-shaped duct 433-1, and has a hollow space defined therein. A fastening bolt 200a is formed at the rear end of the driving shaft 200, and a fastened nut 430b is provided within the propulsion unit 2 so that the fastening bolt 200a can be securely coupled with the fastened nut 430b with the fourth coupling part 430 being interposed between the fastening bolt 200a and the fastened nut 430b. The fastened nut 430b is formed at the front end thereof with a nut support 430a for supporting the fastened nut 430b. At this time, in the case where the fastened nut 430b and the nut support 430a are coupled with each other, their coupling section assumes a trumpet shape. Further, the nut support 430a has a hollow space defined therein dissimilarly to the fastening nut 430b. The fourth coupling part 430 has a larger surface area formed at a portion coupled to , the driving shaft 200 and a smaller .surface area formed at a portion coupled to the propulsion unit 2. FIG. 54 is a cross-sectional • 'view illustrating a modified embodiment of FIG. 53. In FIG. 54, the fluid reflective plates 433a and the fourth reflective plate 431 formed at the rear surface of the fourth coupling part 430 are omitted in the construction of the propulsion unit 2 of the fifth embodiment. Like this, when the fluid reflective plates 433a are excluded, the distal ends of the fourth trumpet-shaped ducts 433-1' is fit into the fourth wings 434-la in such a fashion as to be arranged perpendicularly to the fourth wings 434-la. The operation of the inventive fluid propulsion apparatus having the construction of the fifth embodiment as described above will now be explained hereinafter. The operation of the propulsion unit 2 of the fifth embodiment is basically similar to that of the rear propulsion unit 102 of the fourth embodiment. That is, when the propulsion unit 2 rotates at a high speed, fluid moving past the propulsion unit 2 is introduced into spaces defined between the fourth wings 434-la of the fourth accelerating suction parts 434-1 at a high pressure. At this time, the introduced fluid is branched off to the right and left sides with respect to each fourth front reinforced rib 434-lb. Some of the branched fluid collides against the fourth reflective plates 433a and then is directed toward the back so that it is introduced into the fourth trumpet-shaped ducts 433-1, whereas the others of the branched fluid is introduced into spaces defined between the fourth wings 434-la and the next fourth fluid reflective plates 433a along the rear surface of the fourth reinforced ribs 434-lb. In this manner, the fluid introduced into the fourth trumpet-shaped ducts 433-1 through the fourth accelerating suction parts 434-1 joins the fluid sucked into the fourth trumpet-shaped ducts 433-1 of the propulsion unit 2 from the front of the propulsion unit 2, so that the flow amount1 of .the fluid inside the fourth trumpet-shaped ducts 433-1 is increased and the flow speed of the fluid is further accelerated while continuing to pass through narrower outlets of the fourth trumpet-shaped ducts 433-1. Such an operation is continuously performed as the number of trumpet-shaped ducts is increased, and hence the flow speed of fluid is further accelerated, thereby creating a more powerful thrust or propulsive force. In particular, the above-mentioned trumpet-shaped ducts also serve as a rigid structure which maintains the entire contour of the fluid propulsion apparatus, so that although the fluid propulsion apparatus is lengthened, it is prevented from being downward deflected due to its own weight or rotational force. A fourth discharge part 416 is formed at the rear end of the last fourth trumpet-shaped duct 433-1 of the propulsion unit 2 so that the resultant fluid is discharged to the outside therethrough. Moreover, the fourth discharge part 416 is defined internally with a hollow space, which acts to produce buoyancy in the propulsion unit 2. Thus, although the propulsion unit 2 is lengthened, its downward deflection is somewhat offset by its own weight. The present invention as operated above is coupled to a ship by means of fastening action between the fastening bolt 200a formed at the rear end of the driving shaft 200 and the fastened nut 430b provided within the propulsion unit 2. In addition, the fastened nut 430b is formed at the front end thereof with a nut support 430a for preventing the fastened nut 430b from being swung. At this time, in the case where , the fastened nut 430b and the nut support 430a are coupled with each other, the outer contour of the fastened nut 430b and the nut support 430a assumes a trumpet shape of which outer surface is curved, so that the fluid sucked in through the fourth accelerating suction parts 434-1 is smoothly introduced into the propulsion unit along the trumpet shaped surface of the fastened nut 430b and the nut support 430a without any resistance against the fluid. The fourth coupling part 430 coupled with the driving shaft 200 has a larger surface area formed at a portion coupled to the driving shaft 200 and a smaller surface area formed at a portion coupled to the propulsion unit 2, so that the propulsion unit 2 cab be securely coupled to the driving shaft 200 without any vibration or displacement even upon its high-speed rotation. In case of the propulsion unit of the fifth embodiment as described above, the number of the fourth trumpet-shaped ducts 433-1 may be optionally modified depending on the need of a user. Even in the case where the fluid reflective plates 433a and the fourth reflective plate 431 are omitted in the construction of the propulsion unit 2 of the fifth embodiment shown in FIG. 54, the basic working effect of the propulsion unit 2 is the same as that in the fifth embodiment. In this case, however, the fluid introduced into the fourth trumpet-shaped ducts 433-1 through the third front accelerating suction parts does not collide against the fluid reflective plates 433a and the fourth reflective plate 431 to be directed toward the fourth trumpet-shaped ducts since the fluid reflective plates 433a and the fourth reflective plate 431 are excluded, but can be introduced into the fourth trumpet-shaped ducts 331-1 along the outer peripheral surfaces of the fourth trumpet-shaped ducts smoothly curved from the distal ends of the fourth trumpet- shaped ducts 433-1.