Hydrodynamic system

Abstract

A hydrodynamic system comprises a conduit with a water inlet 210 to receive a water flow from a body of water 15’, an air inlet 215 which can entrain air from above the water surface into the water fl

Description

FIELD OF THE INVENTION

[001] The present application relates but is not limited to a hydrodynamic system. In particular, the application relates to hydrodynamic systems at least partially submergible in a body of water. BACKGROUND OF THE INVENTION

[002] Hydrodynamic systems may be employed for a variety of purposes, including energy generation, energy recovery, water treatment, air treatment, agriculture, cooling, compressed air production for industrial usage, and other water / wastewater services. Many existing hydrodynamic systems require complex infrastructure and numerous site criteria including geographical formations such as rivers, mountains or valleys in order to operate correctly.

[003] Therefore, the availability of viable sites for deploying such existing systems is extremely limited. Even when viable sites can be found, the construction of existing hydrodynamic systems requires vast amounts of time and money and causes extensive damage and disruption to the local environment. Accordingly, there is a need for improved hydrodynamic systems. SUMMARY OF THE INVENTION

[004] Aspects of the invention are set out in the appended claims. These and other aspects, including examples which are useful for understanding the invention set out in the claims, are also described herein.

[005] There is described herein a hydrodynamic system comprising: a conduit comprising: a water inlet configured to receive a water flow from a body of water; an air inlet configured to entrain air from above a surface of the body of water into the water flow ; and a water outlet configured to discharge the water flow to the body of water; a water turbine disposed in the conduit between the water inlet and the water outlet and configured to receive the water flow and the entrained air; a separator disposed in the conduit between the turbine and the water outlet and configured to separate the entrained air from the water flow after passing through the turbine; a collection chamber configured to collect the separated air, the chamber fluidically coupled to the conduit; and pumping means disposed in the conduit between the separator and the water outlet and configured to pump water from the conduit to the body of water through the water outlet; wherein the conduit is shaped such that, when in use, the turbine and the pumping means are positioned lower than the water inlet.

[006] The conduit may be shaped such that, when in use, the water outlet is positioned higher than or level with the water inlet. The conduit may be shaped such that, when in use, the water flow at the separator is substantially horizontal. The conduit may be shaped such that, when in use, the turbine is located lower than the pumping means (e.g. a pump of the pumping means).

[007] When in use, the pumping means may be positioned higher than the turbine. A vertical distance between the pumping means and the water inlet (when in use) may be at least around 30% of a vertical distance between the turbine and the water inlet. The vertical distance between the pumping means and the water inlet may be around 30% of the vertical distance between the turbine and the water inlet.

[008] The pumping means may comprise an air lift pump configured to provide pressurised air to the water flow in the conduit to pump water out of the water outlet. The pressurised air provided by the air lift pump may comprise pressurised air stored in the collection chamber.

[009] The air inlet may comprise one or more tubes each having a first end portion and a second end portion. The first end portion may be configured to receive air from above the surface of the body of water when in use. The second end portion may be disposed in the conduit and configured to provide air substantially parallel to the water flow when in use.

[010] The collection chamber may be configured to store air pressurised to at least around 5 bar. The collection chamber may be configured to store air pressurised to at least around 10 bar. The skilled person will also appreciate that higher or lower pressures may be achieved depending on the system size and depth (head height). The system may further comprise an air turbine fluidically coupled to the collection chamber and configured to receive pressurised air from the collection chamber. This can allow the stored pressurised air to be used for generating electricity. The pressurised air generated by the system may be used for other purposes. For example, it may be used to provide fresh, clean, dry and cool air for an environmentally friendly air cooling system. The system may also be used for facilities or buildings which require both electricity and cooling. [OH] The conduit may comprise a plurality of conduit sections. The plurality of conduit sections may be configured to direct the flow of water to the body of water via one or more intermediate bodies of water. Each conduit section may comprise a water inlet and a water outlet. A first conduit section of the plurality of conduit sections may comprise the air inlet. The water outlet of the first conduit section may be configured to discharge the water flow to an intermediate body of water. The intermediate body of water may be positioned below the (primary) body of water. The water inlet of a second conduit section of the plurality of conduit sections may be configured to receive a water flow from the intermediate body of water. The water outlet of the second conduit section or of a further conduit section of the plurality of conduit sections may be configured to discharge the water flow to the body of water. The pumping means may be disposed in the second or further conduit section and configured to pump water from the second or further conduit section to the body of water. The system may comprise a series of conduit sections and intermediate bodies of water configured to return the water flow to the (primary) body of water.

[012] The system (e.g. the conduit) may be at least partially submergible in the body of water. Additionally or alternatively, the system (e.g. the conduit) may be configured to be disposed at least partially on land (e.g. land adjacent the body of water). The system (e.g. the conduit) may be configured to be at least partially disposed underground or above ground. For example, the conduit may be completely submergible in the body of water, or part of the conduit may be configured to be submerged while one or more other parts of the conduit may be configured to be disposed on land (e.g. above ground or underground). The system may further comprise a controller configured to selectively control the pumping means to control the flow of water through the conduit. The system may further comprise one or more recovery turbines configured to receive the flow of water from the water outlet.

[013] There is also described herein a method for operating any of the systems described herein. Any system feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure. Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to system aspects, and vice versa. Furthermore, any, some and / or all features in one aspect can be applied to any, some and / or all features in any other aspect, in any appropriate combination. It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and / or supplied and / or used independently. BRIEF DESCRIPTION OF THE FIGURES

[014] Methods and systems are described by way of example only, in relation to the Figures, wherein: Figures 1A and IB show schematic diagrams of (A) an example hydrodynamic system and (B) the system of Figure 1A in operation; Figures 2A and 2B show schematic diagrams of (A) another example hydrodynamic system and (B) the system of Figure 2A in operation; Figures 3A and 3B show schematic diagrams of (A) a further example hydrodynamic system and (B) the system of Figure 3A in operation; and Figures 4A and 4B show schematic diagrams of (A) a further example hydrodynamic system and (B) the system of Figure 4A in operation. DETAILED DESCRIPTION

[015] Various examples of hydrodynamic systems are described herein. These systems may be used for efficient energy generation. The systems may additionally or alternatively be used for other purposes, for example air pressurisation or water treatment (e.g. water aeration). Advantageously, the system is rapidly deployable in a wide range of environments, including open water environments or closed / controlled environments (e.g. purpose-made, closed systems, such as inland environments).

[016] Referring to Figures 1A and IB, a hydrodynamic system 100 will now be described. The system 100 includes a conduit 105 configured to direct fluid flow along a conduit path. In the example shown in the figures, the conduit is shaped to direct fluid along a generally “U”-shaped path, but in other examples the conduit 105 may have a different shape or define a different conduit path. In some examples, the conduit 105 is formed from a single continuous conduit (e.g. a tube or pipe) or may be formed from a series of conduit sections that are connected together (e.g. from a plurality of tubes or pipework).

[017] The conduit 105 includes a water inlet 110 configured to receive a water flow. The conduit 105 includes a water outlet 120 configured to discharge a water flow. Therefore, water that enters the conduit 105 at the water inlet 110 is generally directed by the conduit along a path and exits the conduit 105 via the outlet 120. In some examples, the water inlet 110 and / or the water outlet 120 may include a valve (e.g. a non-retum valve) for controlling the flow of water through the inlet / outlet. Generally, the water inlet 110 and the water outlet 120 are configured respectively to receive water from and discharge water to the same body of water. For example, a body of water 10 is shown in Figure IB. In some examples, the water inlet 110 includes one or more filters to prevent debris or pollutants from entering the system 100.

[018] The conduit 105 also includes an air inlet 115 which is configured to receive an air flow and entrain that air in water flowing through the conduit 105. For example, as shown in Figures 1A and IB, the air inlet 115 is positioned adjacent the water inlet 110 such that air received at the air inlet 115 is entrained in the water flow received from the water inlet 110 (e.g. substantially at or shortly after entering the conduit). When in use, as shown in Figure IB, the air inlet 115 is arranged to receive air from above a surface 15 of the body of water 10.

[019] In some examples (as shown in Figures 1A and IB), the air inlet 115 comprises one or more tubes each having a first end portion and a second end portion. The first end portion is configured to receive air from an atmosphere above the surface 15 of the body of water 10 when in use. Each tube is configured to direct air received at the first end portion therethrough towards the second end portion, which is disposed in the conduit and configured to provide air substantially parallel to the water flow when in use. As shown in the figures, the air inlet 115 may be positioned at least partially within the water inlet 110 and oriented such that a flow of air through the air inlet 115 is substantially parallel to a flow of water through the water inlet 110.

[020] As shown in Figures 1A and IB, the system 100 also includes a water turbine 130 disposed in the conduit 105 between the water inlet 110 and the water outlet 120. The water turbine 130 is configured to receive water flowing through the conduit (from the inlet 110 to the outlet 120). The turbine 130 may be placed within a conduit section (e.g. pipe or duct), or may define a section of the conduit itself and be connected to separate conduit sections at its inlet and outlet. Since the turbine 130 is located after the water inlet 110 and air inlet 115 (in the direction of flow), the turbine 130 is also configured to receive the entrained air. Therefore, the turbine 130 receives a water-air mixture. The turbine 130 is configured to convert energy from the flow of water and air into kinetic rotational energy of the turbine, which can then be converted to electricity. In some examples, the turbine 130 includes a reaction turbine.

[021] The system 100 also includes a separator 140 disposed in the conduit 105 after the turbine 130. The separator 140 is configured to separate the entrained air from the water flow after passing through the turbine 130. The separator 140 is located in a section of the conduit 105 that is shaped such that, when in use as shown in Figure IB, the flow of water at the separator is substantially horizontal. The separator 140 may include one or more of: a surface, a plate, a baffle, or other body positioned within the conduit. In some examples, the separator 140 is angled in order to deflect air entrained in the water flow in a substantially upward direction (when in use) such that it rises out of the flow of water and becomes separated from the flow. In some examples, the turbine 130 (or a portion of apparatus associated with the turbine 130) may serve the role of a separator to separate entrained air from the water flow, in which case the separator 140 may not be required.

[022] The air separated from the water flow by the separator 140 is then directed towards and collected in one or more collection chambers 150. Accordingly, the chamber 150 is fluidically coupled to the conduit 105. The chamber 150 is preferably arranged such that, when in use, the chamber 150 is substantially above the main conduit path of the conduit 105 such that the separated air may rise into the chamber and the water flow may continue through the conduit 105 (past the separator). In some examples, multiple collection chambers 150 are used in order to increase the capacity of the system 100.

[023] The system 100 also includes pumping means 160 disposed in the conduit 105. The pumping means 160 is configured to pump water from the conduit 105 out of the water outlet 120. This can enable the water flow in the conduit to be returned to the body of water 10 in order to provide a continuous flow of water through the system 100. As indicated in Figures 1A and IB, the pumping means 160 may include one or more pumps (e.g. a mechanical pump and / or an air lift pump). In this example, the pump 160 is disposed in the conduit between the separator 140 and the water outlet 120, although the pump may be disposed in other locations in the conduit (e.g. between the turbine 130 and the water outlet 120).

[024] In the example of Figure 1A, the conduit 105 is shaped such that, when in use, the water outlet 120 is located above the water inlet 110 and above the surface 15 of the body of water 10. However, in other examples (as described below with reference to Figures 2A and 2B), the water outlet may be positioned differently, e.g. level with or below the water inlet. In either case, the water outlet 120 is preferably configured to discharge water from the conduit substantially horizontally in order to reduce the chance of back flow into the conduit 105.

[025] The conduit 105 is shaped such that, when in use, the turbine 130 and the pumping means 160 are positioned lower than the water inlet 110. As shown in Figures 1A and IB, the pumping means 160 may be positioned in the conduit 105 such that, when in use, the pumping means 160 is above the turbine 130 (in other words, the turbine 130 is positioned lower than the pumping means 160). In the example shown, the conduit 105 is generally “U”-shaped, having a down-flow portion between the water inlet 110 and the turbine 130, a substantially horizontal portion where the separator 140 separates entrained air from the water flow, and an up-flow portion including the pump and terminating at the water outlet 120. The down-flow and up-flow portions of the conduit 105 are configured to be disposed substantially vertically.

[026] With reference to Figure IB, operation of the system 100 will now be described. At least a portion of the system 100 (including the water inlet 110 of the conduit 105) is submergible in a body of water 10. The system 100 may be installed in a body or supply of water that is relatively shallow (compared to a length of the conduit 105) such as a pond or river, as shown in Figure IB. However, the system 100 may also be installed in a deep or open body of water, such as a lake or sea. The dotted areas in Figure IB (and throughout the other figures) are used to generally indicate the presence of water (or an air-water mixture). When installed, the system is oriented in a substantially upright or vertical plane, such that the conduit 105 generally directs water from the body of water downwards and then back to the body of water.

[027] In particular, in the system 100, a flow of water is received from the body of water 10 at the water inlet 110, which flows through the conduit 105 downwardly towards the turbine 130 at a first depth. The flow of water reduces the pressure around the portion of the air inlet 115 that is within the conduit 105. Since the air inlet 115 is also exposed to the air above the water surface 15, the reduced pressure within the conduit causes air to be drawn into the conduit via the air inlet 115 (via a vacuum effect). Thus, the air becomes entrained in the downward flow of water.

[028] As the flow of water and entrained air travels downwards, the entrained air becomes increasingly pressurised due to the column of water above it. Advantageously, this pressurisation of the air is substantially isothermal due to the efficient thermal properties of the surrounding water.

[029] The water flow then passes through the turbine 130 in order to recover energy from the water flow. After passing through the turbine, this air-water mixture is separated such that the pressurised air is collected in the collection chamber 150. Accordingly, the chamber 150 is configured to contain pressurised gas including air (e.g. a pressurised air tank or vessel).

[030] After the entrained air is separated, the water continues flowing through the conduit 105 and due to its hydrostatic pressure and momentum, the water rises part of the way up the conduit (towards the outlet 120), back to a second depth that is less than the first depth. The pumping means 160 then pumps the water back to the body of water 10 through the outlet 120 in order to ensure a continuous flow of water - as shown in Figure IB, one or more pumps 160 pump the water to the outlet 120 which is above the surface 15 of the body of water 10. In other examples, the water outlet 120 may be substantially level with the water inlet 110. Advantageously, the system can allow water to flow through the system and back into the same body of water without introducing pollutants into the body of water that could otherwise harm the environment in the body of water.

[031] In some examples, the conduit 105 is sized to direct the flow of water downwards from the water inlet by a distance (or head height) of at least around 5 m, at least around 10 m, at least around 50 m, or at least around 100 m. This distance may be equal to the first depth described to above. The conduit 105 may be sized to direct the flow of water upwards from the separator 140 by a distance of at least around 3.5 m, at least around 7 m, at least around 35 m, at least around 70 m, at least around 100 m. An up-flow portion of the conduit 105 may have a length that is at least around 70% or at least around 90% of a length of a down-flow portion of the conduit 105. The length of the up-flow portion of the conduit 105 may correspond to the second depth. The system 100 may be configured such that when in use, a vertical distance between the pumping means 160 and the water inlet 110 is at least around 30% of the vertical distance between the turbine 130 and the water inlet 110. The collection chamber 150 may be configured to store air pressurised to at least around 2 bar, at least around 5 bar, or at least around 10 bar. As will be appreciated by the skilled person, other pressures (e.g. higher or lower pressures) may be achieved depending on the system size and depth (head height).

[032] A volumetric flow rate of air through the air inlet 115 may be greater than a volumetric flow rate of water through the conduit, optionally at least around four times greater than the volumetric flow rate of water. The flow rate of water through the conduit may be at least around 5 m3s-1 (e.g. 8 m3s-1), at least around 10 m3s-1, at least around 30 m3s-1, or more than 50 m3s-1. Other flow rates (e.g. larger or smaller flow rates) may be achieved by using a system with different dimensions and / or at different depths (head heights).

[033] The pumping means 160 may be rated to pump water by a height of at least around 1.5 m, at least around 3 m, at least around 15, or at least around 30 m. The pumping means 160 may be driven by an external power supply, preferably a renewable power supply (e.g. derived from solar or wind energy). In some instances, the power required by the pumping means 160 to pump water through the conduit 105 may be reduced when other or additional driving factors are present, such as a swell, tide or natural flow of water. Equally, the power consumption or efficiency of the system 100 may be improved using energy generated by the turbine 130 (e.g. to recover losses from the system 100). In some examples, the system may generate more power (e.g. via the water turbine 130 and / or the compressed air in the collection chamber 150) than that required by the pumping means, so may provide sustainable energy generation.

[034] Other energy recovery mechanisms may also be employed in the system 100. For example, one or more air turbines may be provided in fluid connection to the collection chamber(s) 150. Pressurised air may be provided selectively from the collection chamber(s) 150 to the air turbines in order to generate electricity from the pressurised air. This can allow the system to be used for reliable energy generation (e.g. at times of peak demand). The pressurised air generated by the system can also have other uses, e.g. for environmentally friendly air cooling systems to provide fresh, clean, dry and cool air to buildings or facilities that require electricity and / or cooling (e.g. including but not limited to one or more of: residential buildings, high-rise buildings, hospitals, shopping centres, stadiums / arenas, airports, industrial or religious spaces / buildings). Additionally or alternatively, one or more recovery turbines may be disposed after the water outlet, in order to recover excess kinetic energy imparted to the water flow by the pumping means. For example, when the water outlet is configured to discharge water beneath the water surface (as shown in Figure 2B), the one or more recover turbines may be disposed in the body of water adjacent the water outlet.

[035] With reference to Figures 2A and 2B, another hydrodynamic system 200 will now be described. The system 200 generally corresponds to the system 100, except as described below. The system 200 includes a conduit 205 having a water inlet 210, an air inlet 215 and a water outlet 220, as well as a turbine 230, a pumping means 260 and separator 240 disposed in the conduit 205. The system 200 also includes a collection chamber 250 fluidically coupled to the conduit 205. In some examples, the water inlet 210, air inlet 215, turbine 230, separator 240 and / or pumping means 260 correspond to the equivalent components of the system 100 described above.

[036] However, the conduit 205 differs from the conduit 105 described above at least in that the up-flow portion of the conduit 205 is shorter than the down-flow portion of the conduit. In particular, when in use, the water outlet 220 is positioned lower than the water inlet 210. This can result in the conduit 205 having an asymmetrical “U” shape. The pumping means 260 may also be positioned slightly lower than in the system 100 to accommodate for the shorter section of the conduit 205.

[037] Therefore, when in use in a body of water, the water outlet 220 discharges water from the conduit 205 into the body of water at a certain depth below the surface. Similarly to the system 100 described above, the system 200 may be used with relatively shallow bodies of water (such as the body of water 10 shown in Figure IB) or in relatively deep open bodies of water 10’ as shown in Figure 2B. As shown, the system 200 (including the conduit 205) is submergible under the surface 15’ of the body of water 10’. This can reduce the profde of the system when viewed from above the surface 15’. In addition, by discharging water from the system 200 beneath the surface 15’, disruption to the surface environment can be avoided. For example, this can reduce the impact of the system 200 on the environment / ecosystem at the surface, and can leave a section of water above the main system components that is free from obstruction for water traffic and wildlife.

[038] As described above in relation to the system 100, one or more energy recovery mechanisms may be used in the system 200. For example, since the pumping means 260 pumps water out of the outlet 220 underwater with a certain velocity, one or more recovery water turbines may be positioned near the outlet 220 in order to recover energy from the flow of discharged from the outlet 220.

[039] With reference to Figures 3A and 3B, a further hydrodynamic system 300 will now be described. The system 300 generally corresponds to the systems 100, 200 described above, except as described below. The system 300 includes a conduit 305 having a water inlet 310, an air inlet 315 and a water outlet 320, as well as a turbine 330, a pumping means 360 and separator 340 disposed in the conduit 305. The system 300 also includes a collection chamber 350 fluidically coupled to the conduit 305. In some examples, the conduit 305, turbine 330 and / or separator 340 correspond to the equivalent components of either of the systems 100, 200 described above.

[040] In the example shown in Figure 3A, the conduit 305 has a shape corresponding to the conduit 105 of Figures 1A and IB, but in other examples the conduit 305 may have a shape corresponding to the conduit 205 of Figures 2A and 2B. Similarly to the systems 100, 200 described above, the system 300 may be used either in relatively shallow bodies of water (such as the body of water 10 shown in Figure IB) or in relatively deep open bodies of water (such as the body of water 10’ shown in Figure 2B). In the example of Figure 3B, the system 300 is shown in use with a relatively shallow body of water 10.

[041] As shown in Figures 3A and 3B, the pumping means of the system 300 includes an air lift pump 370. The air lift pump 370 is configured to introduce a supply of pressurised air into the water flow in the conduit 305 (at a greater pressure than the surrounding hydrostatic water pressure). The injected air forms bubbles which reduce the density of the fluid in the conduit 305 and through buoyancy carry the surrounding water upwards. Thus, the flow of water is raised, preferably by an amount sufficient to reach the water outlet 320. For example, the air lift pump 370 may include an opening disposed in the conduit to provide pressurised air into the system.

[042] Thus, in some examples the air lift pump 370 alone is sufficient to pump the water out of the water outlet 320. Using the air lift pump 370 in this way can allow the water flow to be pumped through the system and out of the water outlet 320 efficiently without any moving parts, and can also condition (e.g. aerate or oxygenate) the water in the body of water. In other examples, as shown in Figures 3A and 3B, the pumping means may include both a mechanical pump and an air lift pump. Accordingly, in general the pumping means may include one or both of a mechanical pump and an air lift pump.

[043] The pressurised air provided by the air lift pump 370 may be generated by an air compressor. Alternatively, as shown in Figures 3A and 3B, the air lift pump 370 may use pressurised air that is stored in the collection chamber 350. Accordingly, a pipe or conduit may connect the collection chamber 350 to a portion of the conduit 305 (e.g. the up-flow portion of the conduit) in order to inject at least some of the compressed air stored in the chamber 350 into the water flow in the conduit 305 (e.g. in the up-flow portion). For example, a control valve may be provided to control the amount and / or flow rate of compressed air provided from the collection chamber 350 to the air lift pump.

[044] With reference to Figures 4A and 4B, a further hydrodynamic system 400 will now be described. The system 400 generally corresponds to the systems 100, 200, 300 described above, except as described below. The system 400 includes a plurality of conduit sections 405a, 405b each having a water inlet and a water outlet. In this example, the system 400 includes a first conduit section 405a and a second conduit section 405b, but in other examples more than two conduit sections may be present.

[045] The first conduit section 405a has a water inlet 410, an air inlet 415 and a water outlet 422. The first conduit section 405a may correspond to at least a part of any of the conduits 105, 205, 305 described above. For example, the first conduit section 405a may correspond to the conduit 205 shown in Figures 2A and 2B. The second conduit section 405b has a water inlet 424 and a water outlet 420. The second conduit section 405b may correspond to at least another part of any of the conduits 105, 205, 305 described above. For example, the second conduit section 405b may correspond to part of an up-flow section of the conduit 105 or the conduit 305.

[046] The conduit sections 405a, 405b are generally provided as distinct conduit sections which are configured to be fluidically coupled to one another directly or indirectly, such as via one or more other conduits, components (e.g. turbines, pumping mechanisms or flow control devices), and / or intermediate bodies of water. In use, the conduit sections 405a, 405b are arranged in particular orientations and / or locations relative to each other (as described below). In some examples, the conduit sections 405a, 405b may be configured to be mechanically coupled to or constrained relative to one another (directly or indirectly). When installed, the combination of the conduit sections 405a, 405b may be functionally similar to the other whole conduits 105, 205, 305 described herein - for example, the outlet 420 of the second conduit section 405b may correspond to any of the water outlets 120, 220, 320 described above.

[047] The system 400 also includes a turbine 430, separator 440, collection chamber 450 and a pumping means 460. In the example of Figures 4A and 4B, the turbine 430 and the separator 440 are disposed in the first conduit section 405a and the collection chamber 450 is fluidically coupled to the first conduit section 405a. Accordingly, one or more of the turbine 430, separator 440, collection chamber 450, water inlet 410, air inlet 415 may correspond to the equivalent components of any of the systems 100, 200, 300 described above. In the example of Figures 4A and 4B, the pumping means 460 is disposed in the section conduit section 405b. The conduit sections 405a, 405b may be shaped such that, when in use, the water inlet 410, turbine 430, pumping means 460 and water outlet 420 are positioned similarly to the water inlets, turbines, pumping means and water outlets of any of the systems 100, 200, 300 described above. The pumping means 460 may include an air lift pump as described above (e.g. corresponding to the air lift pump 370), which may use compressed air stored in the collection chamber 450.

[048] Similarly to the systems described above, the system 400 may be used either in relatively shallow bodies of water or in relatively deep open bodies of water. In the example of Figure 4B, the system 400 is shown in use with two relatively shallow bodies of water 10, 20. A first (or primary) body of water 10 is located above a second (or intermediate) body of water 20. One or both of the bodies of water 10, 20 may be naturally occurring, or one of the bodies of water (e.g. the intermediate body of water 20) may be specifically constructed for the system 400. For example, the primary body of water 10 may be a river or pond, and the intermediate body of water may be a water tank installed below (e.g. away from or buried underneath) the river or pond. Accordingly, as shown in Figure 4B, at least part of the system 400 may be submerged underwater and at least part of the system 400 may be located above ground or underground. In other words, the system may be at least partially submergible and / or at least partially configured to be disposed above ground and / or underground.

[049] As shown in Figure 4B, when the system 400 is in use, the water inlet 410 of the first conduit section 405a is configured to receive water from the primary body of water 10 and the water outlet 422 of the first conduit section 405a is configured to discharge the water to the intermediate body of water 20. The water outlet 422 of the first conduit section 405a is positioned below the water inlet 410 of the first conduit section 405a and the surface 25 of the intermediate body of water may be exposed to atmospheric pressure, meaning water can flow unaided from the primary body of water 10 to the intermediate body of water 20 via the first conduit section 405a (e.g. according to connecting tubes theory). In one example, a vertical distance between the water inlet 410 of the first conduit section 405a and one or more of: the pumping means 460, the water inlet 424 of the second conduit section 405b and the intermediate body of water 20, is at least around 30% of a vertical distance between the water inlet 410 and the turbine 430. In one example, a height of an up-flow portion of the first conduit section 405a is around 70% of the height of a down-flow portion of the first conduit section 405a.

[050] The water inlet 424 of the section conduit section 405b is configured to receive water from the intermediate body of water 20 and the water outlet 420 of the second conduit section 405b is configured to discharge the water back to the primary body of water 10. Accordingly, the pumping means 460 is configured to pump water from the intermediate body of water 20 to the primary body of water 10 via the second conduit section 405b. The use of the intermediate body of water 20 in this way can act as a buffer to reduce pressure fluctuations at the pumping means 460. In some examples, water may be returned to the primary body of water 10 via a series of intermediate bodies of water and corresponding conduit sections (with respective pumps). This can reduce the pumping load required by each pump.

[051] As shown in Figure 4B, the water outlets 420, 422 may be positioned above a surface 15, 25 of the respective body of water (as shown). In other examples, one or both of these outlets may be positioned beneath the respective water surface. The water inlet 424 of the second conduit section 405b is positioned below the water surface 25 of the intermediate body of water 20 and preferably below the water outlet 422 of the first conduit section 405a.

[052] While specific systems are shown, any appropriate hardware may be employed. For example, the conduits described herein may be formed of multiple connected conduit sections. In addition, the flow control components (such as pumping means, turbine(s) and / or valves) described herein may be communicably coupled to a controller (not shown) that is configured to selectively control said flow control components in order to control the flow of water through the conduit of the system.

[053] Although the examples herein are described with reference to a body of water in air, the systems may be used for other liquid-gas combinations. Equally, the systems described herein may be used in a variety of environments and scenarios for efficient energy generation and recovery, as well as gas pressurisation and liquid treatment.

[054] The above embodiments and examples are to be understood as illustrative examples. Further embodiments, aspects or examples are envisaged. It is to be understood that any feature described in relation to any one embodiment, aspect or example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, aspects or examples, or any combination of any other of the embodiments, aspects or examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

1. A hydrodynamic system comprising:a conduit comprising:a water inlet configured to receive a water flow from a body of water;an air inlet configured to entrain air from above a surface of the body of water into the water flow; anda water outlet configured to discharge the water flow to the body of water;a water turbine disposed in the conduit between the water inlet and the water outlet and configured to receive the water flow and the entrained air;a separator disposed in the conduit between the turbine and the water outlet and configured to separate the entrained air from the water flow after passing through the turbine;a collection chamber configured to collect the separated air, the chamber fluidically coupled to the conduit; andpumping means disposed in the conduit between the separator and the water outlet and configured to pump water from the conduit to the body of water through the water outlet, wherein the pumping means comprises an air lift pump configured to provide pressurised air into the water flow in the conduit to pump water out of the water outlet;wherein the conduit is shaped such that, when in use, the turbine and the pumping means are positioned lower than the water inlet.

2. The system of claim 1, wherein the conduit is shaped such that, when in use, the water outlet is positioned higher than or level with the water inlet.

3. The system of claim 1 or 2, wherein the conduit is shaped such that, when in use, the water flow at the separator is substantially horizontal.

4. The system of any preceding claim, wherein, when in use, the pumping means is positioned higher than the turbine, preferably wherein a vertical distance between the pumping means and the water inlet is around 30% of a vertical distance between the turbine and the water inlet.

5. The system of any preceding claim, wherein the pressurised air provided by the air lift pump comprises pressurised air stored in the collection chamber.

6. The system of any preceding claim, wherein the air inlet comprises one or more tubes each having a first end portion and a second end portion, the first end portion configured to receive air from above the surface of the body of water when in use, and the second end portion disposed in the conduit and configured to provide air substantially parallel to the water flow when in use.

7. The system of any preceding claim, wherein the collection chamber is configured to store air pressurised to at least around 5 bar, preferably at least around 10 bar.

8. The system of any preceding claim, further comprising an air turbine fluidically coupled to the collection chamber and configured to receive pressurised air from the collection chamber.

9. The system of any preceding claim, wherein the conduit is submergible in the body of water and / or configured to be disposed at least partially on land.

10. The system of any preceding claim, further comprising a controller configured to selectively control the pumping means to control the flow of water through the conduit.

11. The system of any preceding claim, further comprising one or more recovery turbines configured to receive the flow of water from the water outlet.

12. The system of any preceding claim, wherein the conduit comprises a plurality of conduit sections, each conduit section comprising a water inlet and a water outlet.

13. The system of claim 12, wherein the plurality of conduit sections are configured to direct the flow of water to the body of water via one or more intermediate bodies of water.

14. The system of any of claims 1 to 12, wherein the conduit is formed of continuous pipework.

15. The system of claim 14, wherein the conduit is formed from a single continuous pipe.