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Flow Oscillation Generator

This invention relates generally to a flow oscillation device and more particularly to a fluid flow oscillation generator using a fluid such as water or air to generate a primary typically reciprocal motion to drive an electrical machine to provide electrical energy.

Convenient means to generate motion which can be used directly to drive machinery such as a pump or to drive an electrical machine are always an objective. Furthermore provision of generators and means to generate motion for energy recover and/or low carbon and/or sustainable operation have additional advantages. Most means to generate motion use an engine which may consume fuels or have relatively complex turbines or other mechanisms to harvest and generate sustainable energy sources such as wind or water flows whether gravitational or tidal or thermal. Such complexity can present cost, maintenance and sustainability limitations upon wide spread use and also limit usage of such technologies in less developed economies or in smaller micro or mini installations such as for individual or small groups of dwellings as compared to macro installations such as a hydro dam project where there are economies of scale. Aspects of the present invention attempt to provide a fluid flow oscillation generator which is less complex and easier to implement in a wide range of situations for short term or longer term operational use.

In accordance with aspects of the present invention there is provided a motion generator comprising an aperture for fluid flow and a buoyant plug for the aperture, the plug urged to substantially alignment with the aperture for substantially perpendicular movement relative to the aperture in a flow through the aperture, the plug associated with an actuator element, the plug and the aperture reciprocally shaped such that, with the relative buoyancy and/or elasticity of the plug in a fluid flow, the plug oscillates in a fluid flow in use through the aperture to provide a reciprocal motion in the actuator element.

The actuator element may be a plunger. The actuator element may be locked by a locking member in place to prevent or limit reciprocal motion. The locking member may define a range for the reciprocal motion. The locking member may be such that the plug may be locked in the aperture to close the aperture and/or locked to maintain the aperture open at a desired width. T/EP2015/058255

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The plug may have fixed buoyancy defined by material type, structure and configuration. The plug may have an electively variable buoyance provided by means to add and/or remove weight to the plug. The plug may be hollow. The plug may include a pressure regulation means. The plug may have an undulating surface. The plug may have symmetrical or asymmetrical buoyancy in a fluid flow.

The generator may have guide means to define the direction of the reciprocal motion. The guide means may be a sleeve or funnel about an inlet side of the aperture. The guide means may be a sleeve or funnel about an inlet side of the aperture. The guide means may be associated with the actuator element.

A well may be formed by an upstanding wall around the aperture. The aperture may be wider on an outlet side. The aperture may be formed by a number of holes in a pepper pot configuration. The holes may be of the same size or vary in size between each other. The holes may be in a regular distribution or a desired non-uniform distribution for association with the plug to define and control oscillation in the fluid flow. The aperture may have spiral or groove shaping about the aperture to generate swirl in a fluid flow thorough the aperture. The aperture may have means to allow dynamic variation in aperture size.

The aperture and so plug may be presented horizontally or vertically in use.

Also in accordance with aspects of the present invention there is provided a generator arrangement comprising a plurality of generators as described above. The actuator elements may be linked or independently operable.

Additionally according to aspects of the present invention the actuator element may be associated with an electrical machine whereby the reciprocal motion can be used to drive the machine whereby electrical power is generated. The actuator element may be associated with a machine such as a pump whereby the reciprocal motion drives the machine.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: EP2015/058255

Figure 1 a) to f) provides illustrations of respective stages of operation of a fluid flow oscillating generator in accordance with aspects of the present invention;

Figure 2 a) to provides illustrations of various plug shapes which can be utilised in accordance with aspects of the present invention;

Figure 3 a) to b) show different internal configurations of a plug in accordance with aspects of the present invention;

Figure 4 a) to g) provides illustrations of aperture configurations in accordance with aspects of the present invention;

Figures 5 a) to b) provide illustrations of guide means to at least urge desired reciprocal motion in accordance with aspect of the present invention;

Figure 6 a) to c) provides illustrations of inlet and exit configurations of an aperture in accordance with aspects of the present invention;

Figures 7 a) to b) illustrate respectively convex and concave configurations respectively of apertures in accordance with aspects of the present invention;

Figures 8 a) to b) illustrate plug configurations where the plug enters or sits upon respectively an aperture in accordance with aspects of the present invention;

Figure 9 illustrates in side elevation an aperture configuration in accordance with aspects of the present invention having a plurality of holes;

Figure 10 is a plan illustration of the aperture configuration illustrated in figure 9 with arrows showing flow direction;

Figure 1 1 is a side illustration of an aperture configuration in accordance with aspects of the present invention with shaping to generate whirl in a flow through the aperture; Figure 12 is a plan elevation of the aperture configuration as depicted in figure 11 with arrows to illustrate a whirlpool effect;

Figure 13 a) to e) illustrates stages of various generator arrangements with an electrical machine such as a dynamo or other machine such as a pump associated with an actuator element such as a plunger arm of the generator in accordance with aspects of the present invention to drive the electrical machine or other machine;

Figure 14 provides a schematic illustration showing position of a generator in accordance with aspects of the present invention in a dam arrangement also associated with a hydroelectric power generation system using a turbine;

Figure 15 shows a single generator in accordance with aspects of the present invention used in association with a shallow dam or weir;

Figure 16 shows a plurality of generators in accordance with aspects of the present invention associated with a shallow dam or weir; P T/EP2015/058255

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Figure 17 shows a number of generators in accordance with aspects of the present invention in a cascade at different levels in a dam;

Figure 18 a) and b) illustrates operation of a generator in accordance with aspects of the present invention using tidal flows;

Figure 19 illustrates a generator in accordance with aspects of the present invention used in a lateral configuration;

Figure 20 illustrates a number of generators in accordance with aspects of the present invention located horizontally in a dam or weir with different configurations dependent upon height;

Figure 21 illustrates a lateral generator in a fluid flow with a siphon effect to draw flow thorough the generator; and,

Figure 22 provides a schematic illustration of a generator in accordance with aspects of the present invention utilising a combination of air and liquid fluid flows for energy recovery.

Fluid flows through an aperture can be used to provide a means for generation of a reciprocal motion in accordance with aspects of the present invention by combining a plug which is buoyant in a fluid flow about the aperture. The plug is normally rendered buoyant by the nature of the materials from which it is made and configuration with a hollow construction. However, it will also be understood that an actuator element may have some form of spring or bias action which is in balance with the fluid flow much as a ball on an elastic string. In such circumstances the plug will bounce or bobble into and out of the aperture with the fluid flow in a reciprocal oscillation motion. The level of buoyancy may be adjusted to achieve the desired reciprocal motion in the present fluid flow and other conditions. Such level and variation of buoyance may be achieved by fluid ballast variation in the plug so to reduce buoyance water will enter the plug and to increase buoyance water will be removed may by positive pumping but more likely by compressed air displacement of the water out of the plug. Such variations in buoyancy will typically not be significant but sufficient to tune the reciprocal motion to a desired result to act as a prime mover for a machine or electrical machine to generate electrical power. The pressure in the hollow plug may be regulated by a pressure regulation device to again control buoyancy in use as required.

Figure 1 provides illustrations in a number of drawings Figure 1a) to Figure 1f) showing stages of operation of a schematic fluid flow generator 1 in accordance with aspects of the present invention. It will be understood when a fluid such as water passes an obstruction such as a plug 2 on a plunger adjacent an aperture 4 there is a narrow gap 6 for that fluid flow. This narrow gap increases downside pressure below the aperture by the known Bernoulli Effect. The narrow gap 6 or channel causes a local increased fluid pressure so the drawing or down side pressure on the other outlet side of the aperture 4 overcomes the present buoyancy of the plug 2 and the elasticity of the support to the plug on its actuator.

In figure 1a) the generator 1 includes the plug 2 upon an actuator element 3 which in combination acts as a plunger above the aperture 4. A fluid flow illustrated by arrowheads 5 passes through the aperture 4 via a gap 6 between the plug 2 and the edges of the aperture 4. This gap 6 narrows by drawing the plug 2 down with the downside pressure generated by the Bernoulli Effect as illustrated in Figure 1b) and Figure 1c) so that the decreasing gap increases the downside pressure sucking the plug 2 into the aperture 4 until as illustrated in Figure 1d) the gap 6 is closed and the down side pressure, because there is no fluid flow, returns to zero or substantially zero. In such circumstances as illustrated in Figure 1e) plug 2 buoyancy and elasticity in the suspension of the plug 2 on the actuator element 3 again returns as the dominant forces in the generator. The buoyancy (shown by arrowheads 7) and elasticity (shown by arrowheads 8) urges the plug 2 upwards again opening the gap 6 so that fluid flow 5 again occurs with a down side pressure drawing the plug 2 into the aperture 4 as previously. This cycle creates a reciprocal motion in the plug 2 and so actuator element 3 which can be used drive a machine or electrical generator as described later. It will be understood that to maximise efficiency a careful balance between forces (buoyancy/elastic suspension compared the downside force of fluid flow through the aperture 4) is needed. It will also be understood that free operation of these forces is also required so that the abutting surfaces of the plug 2 and the aperture 4 should be such that there is preferably a non-stick engagement.

It will appreciate to achieve the desired reciprocal action of drawing the plug 2 into the aperture with down side force and bounce with buoyancy and elasticity that appropriate combinations of plug and aperture are required in order to provide the necessary gap for fluid flow. The shape of the aperture and the plug will define the nature of gap increase and decrease as the plug moves relative to the aperture towards it and away with buoyancy. Figure 2 provides in drawings Figure 2a) to Figure 2f) some examples of possible plug shapes. These shapes will vary gap opening and closing regimes with displacement but also present more or less turbulence or uneven fluid flow so that a desired variation or maintenance of fluid pressure gradients can be achieved. In Figure 2a) a bulbous plug configuration 22 is illustrated with a rounded end 22a and a radial bulbous skirt 22b such that in use the rounded end will typically enter and withdraw from an aperture with a non-linear rate of gap change whilst the skirt 22b may more abruptly close or even seal the aperture towards the end of the desired reciprocal movement. Figure 2b) illustrates a conventional spherical ball plug configuration 32 which may provide easy of manufacture and more predictable performance. Figure 2c) provides a downward facing dome plug configuration 42 so that a centre 42a with displacement of the plug 42 will enter an aperture and the shaping of the dome helping provide a smooth fluid flow over the plug 42 with less turbulence. Figure 2d) shows a plug 52 having an upstanding dome configuration for possibly outward spread of a fluid flow from above but more importantly a cushion end 52a to engage with the aperture which may affect downside pressure as well as provide an elastic deformation which can be utilised for the reciprocal motion action. Figure 2e) again illustrates an upstanding dome 62 configuration but with a chamfered centre 62a to location more precisely in an aperture in use. Figure 2f) illustrates the simplest form of plug as a disc or cylinder 72 which as described previously can either sit and engage on one side of the aperture or enter the aperture to extend across it to reduce the gap width or increase the width as required to provide the bouncing action for reciprocal motion in accordance with aspects of the present invention. In terms of determining the appropriate plug configuration it may be that the most efficient plug head can be determined but the length of the plug can have a bearing on the water flow in terms of turbulence and diverting the water in the most streamlined manner.

In order to provide buoyancy typically as illustrated in Figure 3 the plug head will be hollow. In the drawing provided by Figure 3a) a hollow cylindrical plug 23 is illustrated in transparent front perspective view whilst in Figure 3b) a hollow spherical plug 24 is illustrated. A plug in accordance with aspects of the present invention will be generally formed from any of a wide range of materials including metals and plastics materials. The hollow form will mean that the plug as a whole has a specific gravity less than the fluid about it. This buoyancy may be fixed in that the plug is a closed hollow structure or may be adjusted on set up of the generator or dynamically. For example an actuator element 25 which acts as a plunger shaft can be adjusted so that more or less of its weight adds to that of the plug 23 in determining buoyancy and/or this element 25 could include a pipe whereby small amounts of water or other ballast could be pumped into the hollow core and then removed if required by pumping out or by compressed air blasts. It will also be understood in some circumstance an uneven or non-symmetrical distribution of weight in the plug may be advantageous so as illustrated in Figure 3b). The walls of the plug may be thicker in parts or an additional weight provided at parts 26 to load the weight distribution in the plug 24 which may have advantages in terms of engagement with an aperture in use and/or buoyancy response of the plug in use and/or guidance/urging of the plug to a desired reciprocal motion derived by the down side pressure drawing the plug to the aperture and buoyancy lifting the plug away in a repeated cycle.

A plug in accordance with aspects of the present invention acts in cooperation with an aperture so the shape, size and configuration of the aperture will affect performance. Figure 4 provides drawings Figure 4a) to Figure 4g) of different aperture configurations. Figure 4a) illustrates a conventional round hole aperture 34 so subject to flutter a plug will generally be centrally located to give a substantially even gap around the circumference of the aperture 34. Figure 4b) illustrates a feathered or slotted aperture 44 which again is generally round but has slots so that a fluid flow is maintained even in full engagement with a plug so altering the down side pressure/upward buoyancy-elasticity balance relationship and so the reciprocal motion response. Figure 4c) provided a square hole aperture 54 so that either a similarly shaped plug will be required or the angular corners of the aperture will provide maintained gaps for flow and so the oscillation reciprocal motion will be controlled by that feature. Figure 4d) illustrates a fluted aperture 64 shape, Figure 4e) a triangular aperture 74 shape, Figure 4f) illustrates a chamfered corner aperture 84 shape and Figure 4g) a star aperture 94 shape so that with each of these aperture shapes it will be understood that the lack of a smooth curve means that the plug to aperture relationship is not generally complete so that the gap for fluid flow will either be maintained or not develop linearly with plug to aperture off set in the reciprocal motion giving choices to a designer in terms of performance and responses for different circumstances. In any event normally the approach will be to ensure the entry for the water or other fluid in to the aperture is most efficient so for instance the star shape of aperture 94 may have a longer overall edge that may increase down side pressure. It will be appreciated that the plug associated with each aperture will normally be a substantive negative impression of the aperture shape used.

In order to provide the desired down side pressure at least consistently it will be understood that the plug to aperture association should be regulated. Thus, as illustrated in Figure 5 the entry or inlet side to an aperture 104, 204 could be guided by a straight cylindrical guide 100 (figure 5a)) or a wider funnel 200 (figure 5b)) in order urge a plug 102, 202 in to appropriate presentation to the aperture 104, 204. It will be understood that the guide 100, 200 will have an effect upon the up lift pressure due to buoyancy/elasticity in the generator and down pressure due to the Bernoulli Effect. This effect could be positive or negative so care will be needed in actual design choices. For example perpendicular presentation and movement of the plug relative to the plane of the aperture may be desirable for better down pressure control but a close cylindrical sleeve guide 100 may mean there is more friction and constriction of the plug in the buoyant up lift phase of reciprocal motion which could have a negative effect. Alternatively if a funnel approach as illustrated by guide 200 in figure 5b) is used then the plug 202 is not so closely guided relative to the aperture 204 so a least consistent down side pressure will be achieved but up lift movement in the plug. The actuator element will be less constrained so less friction losses but also there will be more 'wander' of the actuator element to a machinery coupling which must be accommodated.

Similarly to the considerations on the inlet or entry side of the aperture described above on the exit or outlet side of the aperture there will be affects upon down side pressure and uplift buoyance by the nature of the shape of the exit to the aperture. Figure 6 provided drawings Figure 6a) to Figure 6c) which illustrate some of the options given that the inlet side can be a closer controlled guide such as a cylindrical sleeve or a lesser controlled guide such as a funnel. The exit side can either be straight or again a funnel shape. A funnel shape on the exit side would reduce buoyancy on the inlet side of the plug as it would mean that the fluid such as water passing through the aperture meets less resistance as it passes through the aperture but this may increase pressure differences. A balance needs be struck in actual generator design to ensure the desired reciprocal motion of the plug/actuator element to a machine is achieved.

In Figure 6a) an aperture 114 has a less close guide in the form of a funnel inlet 110 and an expansive outlet side to the aperture 114 in the form of a funnel 1 15 so a relatively greater down side pressure may be achieved to draw a plug 112 to the inlet side of the aperture. Once in the thrall of the down side pressure the reciprocal motion may be quicker and/or more forceful at this stage of the reciprocal motion cycle. In figure 6b) an inlet side of an aperture 214 has a less close guide in the form of a funnel inlet 210 but in this example an outlet side of the aperture is more constrained in the form of a guide sleeve 215 so the down pressure is more limited and/or controlled altering the speed and/or forcefulness of the reciprocal motion at different stages of the cycle. In figure 6c) an inlet side of an aperture 314 has a closer guide in the form of a sleeve 310 in which a plug 312 is more restrained to a perpendicular straight up and down reciprocal motion relative to the aperture 314. This may cause more friction but provides more regularity in the reciprocal motion to a coupling to a machine. An exit or outlet side has an expansive shape provide by a funnel 315 so possibly a greater down side pressure may be achieved overcoming additional guidance constriction on the inlet side provided by the closer cylindrical guide sleeve 31 .

In view of the above it will be appreciated that that by choices of the inlet and outlet side configurations along with the plug shape and aperture shape that changes to the speed and forcefulness of the reciprocal motion over a whole oscillation cycle can be achieved. This approach can help tune a generator in accordance with aspects of the present invention to the particular requirements and operational conditions of a machine or electrical power generator coupled to the oscillation generator for best performance.

The engagement of a plug with its aperture in a generator according to aspects of the present invention is important in particularly the 'closure' stages of the reciprocal motion cycle. Figure 7 illustrates in drawings figure 7a) and figure 7b) respectively a convex configuration 90 and a concave configuration 91. It will be appreciated that such convex 90 and concave 91 configurations mean that there is effectively an upturned rim or a downturned rim to the apertures so that there is greater or less surface to surface contact between the plug and the aperture which will effect down side pressure development. Such surface to surface contact will also affect the 'stickiness' of the contact and so may also effect the oscillation cycle at that stage. The surface of the plug may also be undulated or shaped to limit adhesion and facilitate quick release of contact when required.

A plug in accordance with aspects of the present invention may enter an aperture or sit to one side of the aperture. Figure 8a) illustrates at the closure stage of an oscillation cycle a plug 122 in an aperture 124 with the plug 122 extending across the aperture 124 to plug or close the aperture 124. Figure 8b) illustrates the closure stage of a plug 222 on one side of an aperture 224. Entry of an aperture or sitting on top of the aperture will affect the balance between down side force and buoyance/elasticity uplift in the reciprocal motion of the oscillation cycle.

As illustrated above an aperture in accordance with aspects of the present invention may comprise a simple single hole or aperture so that the plug and aperture can interact to provide the reciprocal motion as an oscillation of the plug in a fluid flow through an aperture. An alternative as illustrated in Figure 9 and Figure 10 is to provide an aperture in the form of a plurality of holes 134 arranged in pattern such as a pepper pot so that lines of down side force 130 into an 'aperture' are provided. The holes 134 may all be the same size, regularly spaced and regular shape or different sizes, spaced as required to provide desired down side force and differently shaped also to tailor the down side forces. It will be understood that by distributing fluid such as water all around the plug such that floating may give a more even down side force distribution around the plunger plug in use.

As indicated above one advantage of a funnel like inlet side to an aperture in accordance with aspects of the present invention is that there may be less friction and other losses compared to a more constrictive sleeve guide. Nevertheless some urging or guidance towards an aperture would be advantageous in terms of developing the down side pressure action in the reciprocal motion defined by the oscillation of the plug in use. Figure 11 and Figure 12 provide schematic cross-sectional views of one approach to achieved guidance or urging of the plug towards an aperture with a whirlpool or vortex effect. As previously an aperture 234 is provided generally in the centre of a funnel 230 on the inlet side of the arrangement. Within the funnel 230 there are provided grooves or fins or jets 231 which act to generate a swirl in a fluid flow through the aperture 234 which in turn defines a whirlpool or vortex effect (shown by arrowheads 232) to engage a plug (not shown) towards the aperture 234. In such circumstances the down side pressure will develop more reliably and predictably as part of the oscillation cycle between down side pressure urging the plug into the aperture 234 then uplift due to buoyancy/elasticity in the generator through the plug and/or the actuator element.

Providing an oscillation generator in accordance with aspects of the present invention using fluid flow through an aperture is generally used to drive machinery and more particularly an electrical machine to generate electrical power. Figure 13 provides in drawings Figure 13a) to Figure 13c) or Figure 13d) to Figure 13e) or Figure 13f) examples of connections of generator arrangements in accordance with aspects of the present invention to a machine so that the prime movement of the generator can be used to drive the machine. In Figures 13a) to c) a motor 400 has a shaft 401 upon which a cam 402 is secured.

The cam 402 in turn is secured by a coupling to an actuator arm or element 403 which has a plug 404 in accordance with aspects of the present invention. The plug 404 will act within an aperture (not shown) so that alternately the plug 404 will be drawn down by a down side force through the aperture as described above and uplifted by buoyancy/elasticity as also described above. The oscillation movements will be in the direction of arrowheads 405 such that as can be seen in the stages illustrated by Figures 13a) to 13b) the cam 402 and so shaft 401 is turned over. The shaft 401 is associated with the motor 401 so that motor is driving itself in a conventional manner to generate electrical power. The shape of the cam 402, length of the element 403 and other configuration features will be determined to achieve desired results from the oscillation generated by the plug 404 as described previously in a fluid flow through an aperture. The motor 401 could be replaced with another machine such as a pump.

The oscillation of the plug 404 is over a reciprocal cycle determined by the fluid flow rate through the aperture (not shown in figure 13) which in turn will define the down side pressure drawing the plug 404 into the aperture until fluid flow is so reduced that the buoyancy/elasticity of the plug/actuator combination overcomes the down side pressure and there is up lift to the other end of the oscillation or reciprocal motion cycle. As described previously the main determinants of such oscillation is the plug to aperture relationship but as indicated buoyancy may be effected by altering the weight of the plug and possibly the weight distribution in the plug, the actuator can include a spring or similar bias element to alter or adjust the elasticity of the connection arm or element which effectively defines a plunger with the plug and if necessary the range of the oscillation and so reciprocal motion can be limited by an end stop to the uplift action at least. A further possibility particularly with a simple single aperture arrangement is to alter the size of the aperture dependent upon current conditions using an iris type shutter to open or close the aperture to a cross section suitable for current fluid flow conditions.

In Figures 13a) to c) a cam 402 is used with a fixed length actuator 403 but as illustrated in Figures d) to e) an alternative is to use a nodding or tilting beam 502 arrangement such that the beam 502 at one end is associated with a motor 500 through a shaft 501 and an actuator element 503 through a coupling 506. The oscillations of a plug 504 in a fluid flow through an aperture (not shown) generates movements in the direction of arrowheads 505 lifting and lower the beam 502 so turning the shaft 501 to drive the motor 500 as required. The element 503 will generally have a bias either using a mechanical spring or due to the material from which the element 503 is made in order to facilitate the oscillation cycle.

Figure 13f) shows an alternative to that depicted in Figures 13d) to e) in that a beam 602 is directly associated with a plug 604 so that oscillation in a reciprocal motion manner are translated to a shaft 601 associated with a motor 600 to drive it. The plug will move in the direction of arrowheads 605 in the fluid flow through the aperture (not shown) using the buoyancy of the plug 604 and elasticity of an actuator element 603 associated with it in dynamic balance with the down side force of flow through the aperture (not shown) in use. Clearly, providing the beam 602 directly associated with the plug 604 will create problems of accommodation in the fluid flow without creating undue turbulence but such configuration is more direct to the motor or machine 600 so mechanical power transmission losses through and via the coupling to an intermediate actuator element will probably be lower.

Aspects of the present invention are particularly directed to recovering potential energy in a fluid flows. Previously it is well known to use dams and down flow of water to drive turbines which in turn drive machinery such electrical power generators. However, such turbines generally require a minimum head of water or fluid to be effective.

Figure 14 shows a fluid flow oscillation generator in accordance with aspects of the present invention used with an existing hydro-dam arrangement 700 in a flow path 701 for a forceful fluid flow to a turbine 702. A plug 703 and an aperture 704 in an oscillation generator 705 act as described above so that the oscillation of the plug 703 is translated by an actuator element 706 to drive a machine as required. Thus with the generator 705 and the turbine 702 it will be understood more of the potential energy of the fluid in the dam is recovered so increasing overall efficiency.

Figures 15 to 17 illustrate various configurations and combinations of fluid flow oscillation generator arrangements in accordance with aspects of the present invention particularly for use in hydro-dam situations. In Figure 15 there is a single stand-alone oscillation generator 800 which as described above may sit atop a dam so that fluid flow down even a shallow drop dam (less than that suitable for a turbine) can be used to generate oscillations and so act as a prime mover to a machine or electrical machine. In such circumstances, a generator in accordance with aspects of the present invention may be used in remote and less developed country locations to provide a power source at that location. The generator 800 has a plug 801 and an aperture 802 with an actuator element 803 to a machine (not shown). Fluid flow will move in the direction of arrowhead 804.

Figure 16 shows a multiple generator arrangement in accordance with aspects of the present invention in which again each of the generators 900 can be along a relatively shallow drop dam but with flow possibly over a much wider front than with regard to Figure 15. In such circumstances each generator 900 can act independently or collectively so that movement of each plug 901 in the fluid flow and so respective actuator elements 903 associated with each plug 901 used to drive machines. An indicated already above aspects of the present invention can be used with a relatively shallow dam height so that in Figure 16 each generator 900 can take a proportion of the fluid flow to drive its own machine or all the actuators 903 can be coupled permanently or as required through the actuator elements 903 in to a single group or a number of combinations to drive one or more machines. At times of low fluid flow shutters or slews or sluices either side may be used to guide and constrain fluid flow to individual or groups of flow oscillation generators in accordance with aspects of the present invention as required.

Figure 17 shows a further approach to using several generators 1000 in accordance with aspects of the present invention collectively or individually to drive one or more machines (not shown). As little water or fluid is actually needed for each generator in accordance with aspects of the present invention as shown in Figure 17 several generators 1000 can be set up as various levels in a decent of fluid in a fluid flow conduit. In such circumstances when conditions dictate such as due seasonal factors or operational requirements one or more generators 1000 in accordance with aspects of the present invention could be switched into operation or out of operation as required. As the generators 1000 will generally be spread out in terms of location it is less likely that the actuator element of each generator 100 will not be mechanically linked to a single machine or electrical power generator.

A generator in accordance with aspects of the present invention could also be in two way flows such as those present in a tidal situation. Figure 18 illustrates in drawings Figure 18a) and Figure 18b) a generator 1100 with a plug 1101 and an aperture 1102 with funnel inlet and outlet sides. The generator 1100 is provided with a weir element 1103 which in the embodiment shown can tilt over a pivot 1104 so that with flow in one direction shown by arrowheads 1106 fluid will flow over the weir 1103 into the inlet funnel and through the generator 1100 (figure 18a) then out of an exhaust downstream whilst flow in the direction 1107 will again pass over the weir element 1 103 but from the opposite direction but again into the funnel inlet side of the aperture 1102 to generate oscillations in the plug 1101 to drive a machine through an actuator element 1108. The weir element 1103 will tip or be driven over the pivot 1104 as required dependent upon tidal or flow direction 1106, 1107 to be utilised. If the element 1103 is tipped over the pivot 1104 then the generator may need to move laterally to different positions. An alternative would be to simply provide the generator 1100 in a well form by walls either side of the inlet rather than a tipping weir element so that excess fluid either side of the well would pass into the funnel inlet side of the generator to provide oscillations in the plug 1101 as described previously to drive a machine through an actuator element connection.

So far fluid flows in accordance with aspects of the present invention have used fluid height and/or gravity to drive fluid flow in a mostly vertical fluid flow generator but there are also forceful lateral flows driven naturally such as in rivers or by pumps for waste. Generators in accordance with aspects of the present invention can also act laterally as illustrated in Figures 19 to 21 using such lateral fluid flows rather than direct fluid flow drops. Such approaches would make use of strong water flows but with limited drops with may be a bank of generators as required.

In Figure 19 a generator 1200 is located in a substantially lateral fluid flow 1201 with again a plug 202 in an aperture 1203. There will be some buoyancy in the plug 1202 but generally elasticity in an actuator 204 will be used in balance with the 'down side' force generated by the fluid flow through the aperture 1203. There may be faster flows through the apertures 1203 so generating more down side force which diminishes as the aperture is closed so that the elasticity of the actuator 204 arm side and buoyancy will cause oscillation in a reciprocal cycle similar to that described previously. However it will also be understood that turbulence at the inlet to the generator may cause problems so provision of an unhindered inlet and outlet to the generator may be a difficulty.

Such problems with flow hindering in the outlet at least may be overcome as illustrated in Figure 20 and Figure 21. In Figure 20 it can be seen that outlets 1201 to generators 1200 may be expansive in the form of a narrow jet exit 1202 into a funnel on the dry side of a dam 1204. In Figure 21 an exit side of a generator 1300 is coupled to a siphon path 1302 ejecting a narrow jet 1304 down flow from the generator 1300 in use. As will be appreciated fluids can be a liquid or a gas or a mix so in accordance with aspect of the present invention gases such as air can be used to provide a dry side generator. Figure 22 illustrates such an arrangement with air moving in the direction of arrowheads 1400 acting upon a plug 1401. Generally the plug 1401 will depend upon elasticity rather than buoyancy as the upward force action in balance with the down side force generated by air fluid flow through an aperture 1402 in to an exit side of the generator depicted in Figure 22. The air flow 1400 will pass through the aperture 1402 in a jet like format and become entrained with a liquid fluid such as a water flow 1403 into an exhaust exit 1404. Although use of air or a gas to provide buoyance to the plug 1401 may reduce the potential uplift this loss of buoyant uplift may be offset with a possible reduction of downward drag (viscosity) by using air instead of fluid around the plunger plug 1401 and may also benefit by reducing turbulence around the plunger plug 1401. It will also be understood that the air and fluid inlet ratios are important to determine efficiencies as well as exhaust outlet size. Entraining air with water at the down side exit will enhance the down side force and so create a better reciprocal oscillation motion cycle. Modifications and adaptation of aspects of the present invention will be understood by persons skilled in the technology. Generators in accordance with aspects of the present technology can be used in a range of areas of technology including with existing dams both laterally and vertically or as stand-alone projects where recovery or use of otherwise unused or less than fully used (exhausted) fluid flows are available. Aspects of the present invention have particular use in relation to projects where there is a low fall fluid flow and has advantages in that only a low flow volume and slow fluid flow rate can be readily accommodated or is necessary. The present generator can be used in rivers and weirs or lock stairs in canal systems and generally anywhere there is a fluid flow occurring naturally or as a result of pumping or waste such as with sewage systems or industrial waste processes. The generators can be permanently installed or used as portable micro- generators for emergencies or for camping or for use in remote situations. It will also be understood that rather than used to drive a traditional electrical machine through a drive shaft that a fluid flow oscillation generator in accordance with aspects of the present invention could provide vibrations to a piezo-electric device.

It will be appreciated by those skilled in the art that any number of combinations of the aforementioned features and/or those shown in the appended drawings provide clear advantages over the prior art and are therefore within the scope of the invention described herein.