Technical Field

The present invention relates to a centrifugal action-reaction turbine.

The term "turbine" refers to a mechanical device adapted to convert the kinetic and the potential energy of a fluid, either liquid or gaseous, into mechanical energy.

The turbine according to the invention can be used in particular, though not exclusively, for producing energy in a hydropower installation.

Prior Art

In a hydropower installation, the main element is the hydraulic turbine used to convert the potential energy of the water contained in a basin or in a watercourse into mechanical energy. Thanks to the coupling between the hydraulic turbine and an electric generator, it is possible to transform the mechanical energy into electric power.

In many countries, the hydroelectric sector plays a key role in the production of energy from renewable energy sources and covers important parts of the domestic demand.

Hydraulic turbines are a type of drive machine comprising mainly a rotor and a stator and are capable of transforming energy from a primary source, in this case the energy contained in water, into mechanical energy, and then, by means of an alternator, into electric power.

Depending on the characteristics of the watercourse and the geodetic head, i.e. the difference in height between the point where the water is drawn and the turbine, different types of turbines are used.

Currently there are mainly three types of turbines, which differ by characteristics and fields of use: Pelton turbines, Francis turbines and Kaplan turbines.

The Pelton turbine works by transforming the potential of the basin located upstream into kinetic energy, without effecting changes in the water pressure, for example by employing suitably designed nozzles.

For this reason the Pelton turbine is defined as an "action" machine.

The Francis turbine is a centripetal flow turbine, i.e. a turbine in which water enters circumferentially and comes out axially from the rotor, rotating by 90° while passing through the rotor.

The Francis turbine, unlike the Pelton turbine, is a "reaction" turbine as the potential energy of water is converted into kinetic energy partly in the stator and partly in the rotor, whereas in "action" turbines this conversion takes place completely in the stator. The Kaplan turbine is an axial flow turbine, i.e. a turbine in which water enters and exits in axial direction (with respect to the rotation axis of the rotor) without undergoing any change of direction while passing through the rotor.

Like the Francis turbine, the Kaplan turbine too is a "reaction" turbine, and therefore the potential energy of water is converted into kinetic energy partly in the stator and partly in the rotor.

However, the use of these types of turbines is limited by the morphological features of the watercourse, i.e. by the flow rate and by the geodetic head, as well as by the way the turbines carry out energy conversion.

For example, Pelton turbines operate mainly in the presence of high falls (from 300 to over 1000 meters) and small flow rates.

Kaplan turbines preferably operate in the presence of low falls (in the order of ten meters) and high flow rates, since they, being axial turbines, process high flow rates and also work with flow rate values in the order of 20-30% of the nominal flow rate.

Francis turbines operate in intermediate conditions.

From the above it is evident that the type of turbine to be installed is to be chosen on the basis of the above characteristics. It will therefore be necessary to choose in advance whether to install an "action" turbine or a "reaction" turbine. This a priori choice constraint may, however, be limiting. For example, if one initially decides to opt for installing an "action" turbine, but over time the features of the watercourse change, making the presence of a "reaction" turbine more beneficial, it will be necessary to change the type of turbine, this making the operation as a whole very burdensome.

One possible solution would be to install different types of turbines (both "action" and "reaction" turbines) within the same site, but in this case the maximum efficiency of all turbines would never be achieved at the same time, due to the structural characteristics of the turbines themselves and their limitation due to the fact that they operate preferably in the presence of certain hydric conditions, this resulting in a lack of efficiency as well as in power and economic waste.

In addition, "reaction" turbines require onerous civil engineering works and electromechanical controls, such as blade inclination control and rotation speed control, to maintain high efficiency at varying flow rates. "Action" turbines, exploiting the kinetic energy of water, require either to be installed in flowing waters, or that the whole water fall be converted into a high kinetic energy water jet and projected against the turbine. However, for a few feet fall the "action" turbines require very low flow rates in order to be efficient/convenient and therefore the output powers are small.

An object of the present invention is to provide a solution to the above problems which does not have the drawbacks of prior art.

A further object of the invention is to provide a solution that is versatile and has a high, steady efficiency, even at varying flow rates, while ensuring maximum power.

A not least object of the invention is to provide a hydraulic turbine that can be industrially manufactured and maintained at low cost.

These and other objects are achieved by the centrifugal action-reaction hydraulic turbine as claimed in the appended claims.

Disclosure of the Invention

The centrifugal action-reaction turbine according to the invention mainly comprises a support structure integral with a stator, connecting means for a rotor, a rotor, and a feed system for drawing a fluid from a penstock. Preferably, said fluid is a fluid selected from the group consisting of: liquids, particularly water, air-like fluids, pressurized gaseous fluids, air, gases, combusted gases, vapor, overheated vapor. Preferably, said penstock is a pressure conduit that conveys the fluid from a basin or watercourse to the hydraulic turbine. Preferably, all the components of the turbine according to the invention are made of wear- resistant material suitable for continuous use in contact with the fluid, such as metal alloys treated for use in fluids (stainless steel) or polymeric substances suitable for this purpose.

According to a preferred embodiment of the present invention, the support structure has a cross shape comprising a central hole and four coplanar arms arranged mutually perpendicular, each arm having two ends, namely a proximal end and a distal end with respect to the hole of the support structure. Alternative embodiments may include, for example, a number of arms ranging from one to ten. In other embodiments it is possible to provide that the distal ends of the arms are integrated in a circular or oval element defining the stator. Irrespective of the preferred embodiment chosen for the support structure, each distal end preferably comprises an anchor base, for example in the form of a plate or flange, provided with means such as screws, bolts or pins, for integrally anchoring the support structure to the stator. In an alternative embodiment, the support structure and the stator are made as a single body, as a single, indivisible element, for example by using the molding technique.

Also according to a preferred embodiment of the turbine according to the invention, the stator has a ring shape and comprises an upper, connecting surface, preferably flat, for connection to the support structure, and a lower surface. Preferably, each base of the arms of the support structure is integrally anchored to the upper, connecting surface of the stator.

Advantageously, the feed system of the turbine according to the invention is spatially located at the center of the rotor. According to a preferred embodiment of the turbine according to the invention, the feed system is a feed pipe comprising at least one hole for the exit of the fluid from the pipe. Said at least one hole is preferably placed at a distal end of the feed pipe with respect to the penstock. According to one embodiment of the turbine according to the present invention, the feed pipe comprises a plurality of holes, for example in a number ranging from one to twenty, mainly depending on the diameter of the feed pipe.

Also according to a preferred embodiment of the invention, the connecting means for the rotor comprise preferably, but not exclusively, an inner sleeve which is integral with the feed pipe and within which at least one bearing, preferably two ring bearings, is/are received for allowing motion of the rotor with respect to the feed tube. The connecting means also preferably comprise spacer washers for eliminating clearances. Sleeve, bearings and washers are enclosed in an external support, integral with the support structure and housed in the hole of the support structure.

Advantageously, the rotor of the turbine according to the present invention comprises at least one radial channel, preferably a number of radial channels ranging from one to ten, which is/are radially arranged around the feed system and within which the fluid flows, said radial channels being preferably substantially mutually coplanar. Each radial channel comprises, with respect to the feed system, a proximal end in flow communication with the feed system and a distal end comprising at least one nozzle for the exit of the fluid from the rotor and being in flow communication with said nozzle.

Advantageously, the rotor according to the present invention further comprises a fluid distribution member located at the center of the rotor and preferably comprising an axial opening communicating with the feed pipe, an internal cavity receiving, or adjoining, the distal end of the feed pipe comprising the at least one hole for the exit of the fluid from the pipe, at least one radial passageway in flow communication and axially aligned with the proximal end of the at least one radial channel within which the fluid flows. Preferably, the number of passageways is equivalent to the number of radial channels provided according to the chosen embodiment.

Advantageously, according to the invention the distal end of each radial channel comprises and is in flow communication with the at least one nozzle for the exit of fluid from the rotor. Preferably, one nozzle is provided for each channel.

According to a first embodiment of the turbine according to the present invention, said at least one radial channel is a channel defined by a radial tube.

In a second embodiment of the turbine according to the present invention, said at least one radial channel is a channel defined by a pair of radial guides.

Advantageously, the at least one radial channel has a diameter and a length greater than the diameter and length of the at least one nozzle associated with the radial channel. This feature results in an increase in the speed of the fluid flowing within the radial channel during the rotation step of the rotor at the nozzle. In this way, the velocity of the jet of fluid exiting the nozzles is higher than the velocity of the fluid contained in the feed system. This feature allows rotary motion of the rotor.

Advantageously, at the at least one nozzle, a plurality of fixed tabs are provided on the stator. The nozzles will be advantageously oriented so that the fluid coming out of the nozzles impacts against said tabs, thus promoting rotation of the rotor with respect to the stator, or rotation of the stator with respect to the rotor, or rotation of both the rotor and stator. The number and size of the tabs vary depending on the stator size. In particular, said tabs are preferably located on the lower surface of the stator and extend over the entire circumference of said lower surface of the stator. Preferably, but not exclusively, each tab comprises a curvilinear face. Preferably, the curvilinear face of each tab faces the nozzles. This feature allows the jet of fluid exiting the at least one nozzle at a high speed, hitting the curvilinear face of the tabs, to cause the rotary motion of the rotor, or the rotary motion of the stator with respect to the rotor, or the rotary motion of both the rotor and stator.

The distal end of the at least one radial channel, according to a preferred embodiment of the invention, comprises a cap to which the nozzle is connected. Said cap, in turn, preferably comprises a pressure switch which measures the fluid pressure within the radial channel. Each nozzle preferably comprises a needle valve, a stepper motor and an electronic circuit board that are functionally connected to said pressure switch. By the term "functionally connected" it is understood that advantageously the fluid pressure measured by the pressure switch is processed by the electronic circuit board, which drives the stepper motor which, by means of the needle valve, regulates the velocity of the fluid flow exiting the nozzle.

According to an alternative embodiment of the invention, the distal end of the at least one radial channel comprises a cap to which the nozzle is connected. Preferably, said nozzle comprises, in turn, a Venturi channel. Preferably, said Venturi channel comprises an open, conical rear end for letting in the environmental air and a front end for letting out the fluid enriched with the environmental air. Advantageously, the conical end of the Venturi channel is oriented in the direction of rotation of the rotor, whereby upon rotation of the rotor the environmental air is sucked through the conical end and into the Venturi channel, wherein the environmental air, passing through the tapered end, is accelerated and pushed into the nozzle, where it contributes to further increase the flow speed of the fluid flowing within the nozzle. These features allow the fluid flow to exit the nozzle at high speed.

In addition, by connecting for example at least three nozzles in series, it is possible to obtain an increase in the speed of the exiting air-like fluid by 7,5 times greater than the value of the speed of the fluid upon entering.

Advantageously, the rotor, or the stator, or both the rotor and stator is/are connected to an electric generator which, by exploiting the motion of the rotor, or of the stator or of both, generates electric current.

On the basis of the above described technical features it is possible to summarize the operating steps of a preferred embodiment of the centrifugal action-reaction turbine, according to the present invention, as follows: a fluid is drawn through the feed pipe from a penstock; the fluid is then introduced in the distribution member of the rotor through the at least one hole in the feed pipe. Through the at least one radial passageway of the distribution member, in flow communication with the proximal end of the at least one radial channel, the fluid passes through the at least one radial channel. The fluid flowing within the at least one radial channel exits through the at least one nozzle and causes rotation of the rotor by virtue of the reaction induced onto the rotor by the exiting fluid. In addition, said fluid, impacting onto the tabs of the stator can also cause rotation of the stator. The rotation of the stator takes place by means of the conversion of the kinetic energy of the fluid exiting the nozzle of the rotor at high speed, in a direction opposite to the direction of rotation of the rotor. The rotor rotates around the feed pipe that is stationary, being integrally fixed to the sleeve. The fluid, exiting under pressure from the at least one nozzle, hits the tabs of the stator, thus exploiting the "action" force to generate further rotary motion of the stator. For optimum turbine operation, the radial channels must have a diameter and a length greater than the diameter and length of the nozzles so as to create, during their rotation, a considerable increase in the velocity of the fluid contained within the radial channels. This configuration allows to obtain a jet of fluid exiting the nozzles at a speed greater than the velocity of the fluid contained in the feed pipe. In this way, the centrifugal force generated by the fluid within the radial channels is exploited to increase the rotation speed of the rotor and thus the energy produced by the turbine. In order to stabilize the angular velocity of the rotor and consequently to prevent the turbine from producing excessive speed, the nozzles comprise in their inside a needle valve which, through a stepper motor, allows adjusting the flow of fluid exiting the nozzles. The stepper motors are powered by an electronic circuit board that processes the signal of the pressure within the radial channels by using the electrical signal taken from the pressure switches mounted on the caps.

The external support of the connecting means for the rotor is integral with the support structure and the stator, allowing, by means of its internal components (inner sleeve, bearings, washers), to make the rotation of the rotor free and independent of the feed pipe which must remain stationary and integral with the fluid feed system. An electric generator can be connected to the rotor, or to the stator, or to both of them, in order to convert the mechanical energy produced by the turbine into electric power.

The centrifugal action-reaction turbine according to the present invention has the advantage of being both an "action" turbine and a "reaction" turbine, this aspect bringing about a significant advantage from the energy viewpoint since, for the same flow rate of processed fluid, the turbine according to the invention produces greater efficiency than the turbines with "action" or "reaction". This result is generated by the synergy between the "reaction", "action" and "centrifugal" forces created during the operation of the turbine according to the invention. As a consequence, therefore, for the same flow rate of processed fluid, the turbine according to the present invention produces greater power than the turbines with "action" or "reaction" alone, whereby the choice of using the turbine according to the present invention is a choice advantageous both from the economic and logistical point of view. By using the turbine according to the present invention a greater production of electric current is indeed obtained by exploiting a single turbine that does not require maintenance or replacement in case of variations of the hydric characteristics of the watercourse. The turbine according to the present invention therefore has the advantages of being versatile and highly efficient even in different water conditions.

The centrifugal action-reaction turbine as described and illustrated is susceptible to numerous variations and modifications, falling within the same inventive principle.

Brief Description of the Figures

Some preferred embodiments of the invention will be given by way of non-limiting examples with reference to the accompanying figures, in which:

- Fig. 1A shows a perspective view from below of a centrifugal action-reaction turbine according to a first embodiment of the invention;

Fig. IB shows a perspective view from above of the turbine of Fig. 1A;

Fig. IC shows a front plan view of the turbine of Fig. 1 A; Fig. ID shows a rear plan view of the turbine of Fig. 1 A;

Fig. 2A shows a partially exploded perspective view of the turbine of Fig. 1A; Fig. 2B shows an exploded perspective view of the turbine of Fig. 1 A;

Fig. 3A shows a perspective view of a longitudinal section of the turbine of Fig. 1A;

Fig. 3B shows a front view of a cross section of the turbine of Fig. 1A;

Fig. 4A shows a bottom perspective view of a centrifugal action-reaction turbine according to a second embodiment of the invention;

Fig. 4B shows a perspective view of a longitudinal section of the turbine of Fig. 4A;

Fig. 4C shows a front view of a cross section of the turbine of Fig. 4A;

Fig. 5A shows a perspective view of a centrifugal action-reaction turbine according to a third embodiment of the invention;

Fig. 5B shows a front view of a longitudinal section of the turbine of Fig. 5A; - Fig. 6A shows an exploded perspective view along a longitudinal section of a nozzle of a turbine of Fig. 5A;

Fig. 6B is a side view of a nozzle of Fig. 5 A.

In all figures, the same reference numerals were used to distinguish equal or functionally equivalent components.

Description of Some Preferred Embodiments

Referring to Figures 1 to 3, a first embodiment of a centrifugal action-reaction turbine according to the invention is illustrated. In the figures, the turbine is generally indicated by reference 1 1.

The turbine 1 1 comprises a support structure 13 integral with a stator 15, connecting means 17 for a rotor 19, a rotor 19, and a feed system 21 for drawing a fluid from a penstock. In this embodiment the fluid drawn from a penstock is preferably a liquid fluid, for example water.

According to this first embodiment, the support structure 13 has a cross shape comprising a central hole 25 and four coplanar arms 23 arranged mutually perpendicular. Each arm 23 has two ends, namely a proximal end and a distal end with respect to the hole 25 of the support structure, the distal end comprising a longitudinal leg 27.

Also according to this first embodiment, the stator 15 has a ring shape and comprises a flat support surface 29 and an opposite surface 31. Each leg 27 of the arms 23 of the support structure 13 is integrally anchored, for example by means of screws, to the flat surface 29 of the stator 15.

Advantageously, the feed system 21 of the turbine 1 1 according to the invention is spatially located at the center of the rotor 19. According to the embodiment of the turbine illustrated in the figures, the feed system 21 comprises a feed pipe 33 comprising a plurality of radial holes 35 for the exit of the fluid from the pipe 33. These holes 35 are preferably placed at a distal end of the feed pipe 33 with respect to the penstock.

According to the embodiment illustrated in the figures, the connecting means 17 for the rotor 19 comprise an inner sleeve 39 rotatably associated with the feed tube 33 by means of a pair of bearings 41 received within the sleeve 39. The sleeve 39 is therefore rotatably supported by the bearings 41 received within the sleeve 39. An external support 43 integral with the support structure 13 and housed in the hole 25 of the support structure 13 houses in turn the inner sleeve 39 and a set of spacer washers 37.

Advantageously, the rotor 19 of the turbine 1 1 according to the present invention comprises six radial channels 45, which are radially arranged around the feed system 21 and within which the fluid, for example water, flows. In this embodiment, each radial channel 45 is defined by a corresponding radial tube 71. Each radial channel 45 comprises, with respect to the feed system 21 , a proximal end 75 in flow communication with the feed system 21 and a distal end 77 comprising a nozzle 55 and being in flow communication with said nozzle for the exit of the fluid from the rotor 19. The rotor 19 further comprises a fluid distribution member 47 located at the center of the rotor and comprising an axial opening 49 for the passage of the feed pipe 33, an internal cavity 51 receiving the distal end of the feed pipe 33 comprising the radial holes 35, six radial passageways 53 each of which is in flow communication and axially aligned with a corresponding proximal end 75 of one of the six radial channels 45 within which the fluid flows.

Advantageously, the distal end 77 of each radial channel 45, according to the invention, is in flow communication with and comprises a nozzle 55 for the exit of the fluid from the rotor.

Each radial channel 45 has a diameter and a length greater than the diameter and length of the corresponding nozzle 55 associated to said channel 45. This feature allows to increase the speed of the fluid flowing within each radial channel 45 during the rotation step of the rotor. In this way, the velocity of the jet of fluid exiting the nozzles 55 is higher than the velocity of the fluid contained in the feed system 21.

Advantageously, at the nozzles 55, a plurality of fixed radial tabs 57 are provided on the stator 15. In particular, said radial tabs 57 are located on the surface 31 of the stator 15. Preferably, each tab 57 has substantially an optimum shape from the fluidodynamic point of view and preferably comprises a curved face 61 facing the nozzles 55. The nozzles 55 are oriented so that the fluid exiting the nozzles 55 impacts against said tabs 57, thus promoting rotation of the stator 15 with respect to the rotor 19 by virtue of the conversion of the kinetic energy of the fluid exiting the nozzle 55 at high speed.

Advantageously, the distal end 77 of each radial channel 45, according to the invention, is closed by a cap 63 to which the nozzle 55 is connected. Said cap 63, in turn, comprises a pressure switch 65 which measures the fluid pressure within the radial channel 45. Each nozzle 55 comprises a needle valve 67, a stepper motor 69 and an electronic circuit board (not shown) that are functionally connected to said pressure switch 65. The fluid pressure measured by the pressure switch 65 is processed by the electronic circuit board, which drives the stepper motor which, by means of the needle valve 67, regulates the velocity of the fluid flow exiting the nozzle 55.

Advantageously, the rotor 19 is connected to an electric generator which, by exploiting the motion of the rotor caused by the passage of the fluid, generates electric current.

Referring to Figures 4A to 4C, a second embodiment of a centrifugal action-reaction turbine according to the invention is illustrated. In this embodiment, the fluid drawn from a penstock is preferably a liquid fluid.

In this second embodiment, the support structure 13 comprises four arms 23 arranged cross-like and surrounded by a circular crown 79 forming a single body with the arms 23. Longitudinal legs 27 integrally connect the circular crown 79 to the stator 15.

In addition, in this second embodiment, the feed pipe 33 comprises an axial hole 35 located at a distal end of the feed pipe 33. The hole 35 communicates with a cavity 51 of the fluid distribution member 47. Around the cavity 51 , radial channels 45 extend, separated by radial guides or partitions 73. Each radial channel 45 is preferably delimited by a pair of radial guides 73 and adjacent channels 45 have a guide 73 in common. The distal end 77 of each radial channel 45 is defined by a corresponding duct communicating with a respective nozzle 55. Said duct further preferably has a conical shape tapered towards the inlet of the corresponding nozzle 55.

According to the invention, the fluid flow passing through the feed pipe 33 and coming from the penstock arrives in the cavity 51 of the distribution member 47 where it undergoes a 90° deviation in a plane parallel to the longitudinal axis of the rotor 19 towards the radial channels 45 and, consequently, towards the nozzles 55. Also according to the invention, the fluid exiting the nozzles 55 impacts against the tabs 57 of the stator 15, thus promoting rotation of the stator 15 by virtue of the action of the fluid exiting the nozzles 55.

Referring to Figures 5A and 5B, there is illustrated a third embodiment of a centrifugal action-reaction turbine according to the invention.

In this embodiment, the fluid drawn from a penstock is preferably a pressurized air- like fluid.

In this third embodiment of the invention, the connecting means 17 for the rotor comprise an inner sleeve 39 rotatably associated to the feed tube 33 by means of a pair of bearings 41 received within the sleeve 39. The sleeve 39 is therefore rotatably supported by the bearings 41 received within the sleeve 39. An external support 43 fixedly connected to a support structure 81a houses the inner sleeve 39.

In addition, in this third embodiment, the feed pipe 33 comprises an axial hole 35 located at a distal end of the feed pipe 33 with respect to the penstock. The hole 35 communicates with a cavity 51 of the fluid distribution member 47. Around the cavity 51 , eight radial channels 45 extend, separated by radial guides or partitions 73. Each radial channel 45 is preferably delimited by a pair of radial guides 73 and, furthermore, adjacent channels 45 have a guide 73 in common. The distal end 77 of each radial channel 45 is defined by a corresponding duct 89 communicating with a respective nozzle 55.

According to this embodiment of the invention, the rotor 19 comprises a drive shaft 95 arranged on the opposite side of the feed system 21 and associated to a pulley 97 for transmitting motion, by means of belts, to a current generator (not shown). The stator 15 is connected to the drive shaft 95 by means of motion-transmitting mechanism 87 comprising a conical couple 91. A first toothed wheel 91a of the conical couple 91 is fixedly connected to the shaft 92 of the stator 15. The shaft 92 is rotatably supported about the shaft 95 by a bearing 92a. A second toothed wheel 91b of the conical couple 91 is fixedly connected to the shaft 95. The rotary motion of the stator 15 is transferred from the shaft 92 of the stator 15to the shaft 95 of the rotor 19 by means of an intermediate idle gear 93, which further reverses the direction of the rotary motion in order to follow the rotation of the shaft 95. The drive shaft 95 is rotatably supported, through bearings 98, by a support 81b arranged between the motion-transmitting mechanism 87 and the pulley 97 and therefore, according to this embodiment, the shaft 95 passes through said motion-transmitting mechanism 87 and the toothed wheels 91a,91b of the conical couple 91.

According to this third embodiment of the invention, both the stator 15 and the rotor 19 are rotatably associated to a fixed structure comprising the support 81 a and the support 81b and are therefore capable of rotating, respectively by virtue of the reaction induced by the fluid exiting the nozzles 55 and by virtue of the impact of the fluid exiting the nozzles 55 against the tabs 57 and the consequent transfer of the kinetic energy of the fluid to the stator 15.

Referring to Figures 6A and 6B, there is illustrated a nozzle 55 of a centrifugal action- reaction turbine 1 1 according to this embodiment of the invention, wherein the fluid passing through the turbine 1 1 is preferably an air-like fluid.

The nozzle 55 comprises, in turn, a longitudinal Venturi channel 83 arranged in flow connection with the duct 89. The flow of pressurized fluid, typically compressed air, coming from the radial channels 45 communicating with the duct 89 passes through a plurality of axial channels 90 arranged circumferentially in the wall of the nozzle 55 until it reaches a front chamber 101 provided in the nozzle 55 and closed by a cap 102. At the front chamber 101 , the direction of the motion of the fluid flow becomes reversed by 180° and passes through the Venturi channel 83 tapered rearwards in the nozzle 55. When passing through the central conical duct 83a of the Venturi channel 83, the fluid flow increases its speed and causes, by virtue of the known Venturi effect, suction of air through a series of radial openings 103 provided in the wall of the nozzle 55. The radial openings 103 are surrounded by a cone 104 circumferentially formed in the wall of the nozzle 55 and oriented towards the front portion of the nozzle 55. In its rear portion, the nozzle 55 comprises an opening 105 from which the fluid, mixed with the air sucked through the radial openings 103, exits. In this way the flow of air-like fluid exiting the rear opening 105 is enriched with the environmental air sucked through the radial openings 103.

The nozzles 55 are oriented so that the pressurized gaseous fluid exiting the nozzles 55 impacts against the tabs 57, thus promoting rotation of the stator 15. The rotation of the rotor 19 takes place as a consequence of the reaction induced by the pressurized fluid exiting the rear openings 105 of the nozzles 55.

The centrifugal action-reaction turbine as described and illustrated is susceptible to numerous variations and modifications, falling within the same inventive principle.