Water intake structure

The present invention relates to a water intake structure according to a first aspect. The structure includes a plurality of elongate members. The elongate members couple together and are trapezoidal in lateral cross-section. There is also provided a water intake structure according to a second aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each said elongate member has first and second exterior surfaces that are planar and a third exterior surface that is outwardly concave.

FIELD OF THE INVENTION

The present invention relates to a water intake structure. In particular, the invention relates to a water intake structure and a hydropower plant incorporating the same.

DESCRIPTION OF THE RELATED ART

Water intake structures with wedge-wire design bars of the known prior art may be arranged so that the sharp leading edges thereof “cut” and divert the bottom layer of water. Capacity may decrease over time as sand and gravel wear away the sharp leading edges of the bars. Reduced screen capacity from any cause may be costly for run-of-river plant operators, as this represents reduced electricity generating capacity and water intake screens may be relatively expensive pieces of equipment to replace. As sand and gravel erode the leading edges of the bars, water is deflected away from the screen instead of being diverted to the intake.

BRIEF SUMMARY OF INVENTION

There is accordingly provided, and it is an object to provide, an improved water intake structure that may overcome the above disadvantages.

There is provided a water intake structure comprising a screen elongate member shaped to optimize water intake capacity in a Coandă-effect screen. The geometric properties of the screen elongate member cross-section are described in detail herein. The water intake structure as herein described may provide an improvement in water intake capacity over known wedge-wire elongate member designs of the prior art.

There is accordingly provided a water intake structure according to a first aspect. The water intake structure includes a plurality of spaced-apart elongate members. The water intake structure includes a plurality of slots. Each slot extends between adjacent pairs of the elongate members. Each elongate member is shaped to promote a Coandă effect with portions of water passing thereon being taken in through an adjacent downstream said slot thereby.

There is also provided an elongate member for a water intake structure according to a second aspect. The elongate member has an outer surface and an upstream-facing surface extending downwards from the outer surface thereof at an acute angle relative to the outer surface thereof.

There is further provided a water intake structure according to a third aspect. The water intake structure includes a plurality of spaced-apart elongate members. Each elongate member includes an inner portion that is rigid and an outer portion along and upon which water flows. The outer portion of the elongate member is made of one of an elastomer and a thermoplastic polymer. The water intake structure includes a plurality of slots. Each slot extends between adjacent pairs of the elongate members, whereby water passes along and upon the outer portions of the elongate members, with portions of said water being taken in through said slots.

There is additionally provided a water intake structure according to a fourth aspect. The structure includes a plurality of elongate members. The elongate members couple together and are trapezoidal in lateral cross-section.

There is yet also provided a water intake structure according to a fifth aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each elongate member has first and second exterior surfaces that are planar and a third exterior surface that is outwardly concave.

There is yet further provided a water intake structure according to a sixth aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each of the elongate members has an outer surface, an upstream-facing surface, and a downstream-facing surface. Each upstream-facing surface extends from the outer surface at an acute angle relative to the outer surface. A beveled edge extends between each outer surface and downstream-facing surface of the elongate member.

There is yet additionally provided a water intake structure according to a seventh aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each of the elongate members is wedge-shaped in lateral cross-section. Each of the elongate members has an outer surface positioned to extend in parallel with a flow of water thereon. Each of the elongate members has a downstream beveled edge.

There is also provided a water intake structure according to an eighth aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each of the elongate members has an outer surface that is outwardly convex. Each of the elongate members has an upstream-facing surface that is outwardly concave in lateral profile.

There is further provided a water intake structure according to a ninth aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each of the elongate members has an outer surface aligned with a front of the structure. Each of the elongate members has an upstream-facing surface facing a top of the structure. Each of the elongate members includes an upper peripheral portion extending between the outer surface thereof and the upstream-facing surface thereof. The upper peripheral portions of the elongate members are curved in lateral profile at least in part.

There is additionally provided a water intake structure according to a tenth aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each of the elongate members has an outer surface aligned with a front of the structure. Each of the elongate members has a downstream-facing surface facing a bottom of the structure. Each of the elongate members includes a lower peripheral portion extending between the outer surface thereof and the downstream-facing surface thereof. The lower peripheral portions of the elongate members are curved in lateral profile at least in part.

There is yet further provided a water intake structure according to an eleventh aspect. The structure includes a plurality of elongate members. The elongate members couple together. Each of the elongate members has an outer surface aligned with a front of the structure. Each of the elongate members has an upstream-facing surface facing a top of the structure. Each of the elongate members has a downstream-facing surface facing a bottom of the structure. Each of the elongate members includes an upper peripheral portion extending between the outer surface thereof and the upstream-facing surface thereof. Each of the elongate members includes a lower peripheral portion extending between the outer surface thereof and the downstream-facing surface thereof. The lower peripheral portion is sloped relative to the upper peripheral portion thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and first toFIG. 1, there is shown a water intake structure, in this example a Coandă screen assembly40. The assembly in this example is part of a hydropower plant42. The plant includes a conduit, in this example a penstock44having an inlet46. The plant42includes a barrier, in this example a dam48which extends across a body of water50. The dam separates the water into a partially elevated upstream portion52and a downstream portion54.

As seen inFIG. 2, the assembly40has a top56, bottom58spaced-apart from the top, and pair of spaced-apart sides60and62extending between the top and bottom thereof. The assembly has a front64and a rear66spaced-apart from the front. The front and rear of the assembly40extend between the sides60and62of the assembly and between the top56and bottom58of the assembly.

Still referring toFIG. 2, the assembly includes an upper member, in this example an accelerator plate68extending along the top56thereof and between the sides60and62thereof. The accelerator plate is elongate and semi-circular in lateral cross-section in this example, with an outwardly convex exterior top surface69.

The assembly40includes a lower member, in this example a runoff plate70extending along the bottom58thereof and between the sides60and62thereof. The runoff plate is elongate and has a right trapezoidal shape in lateral cross-section in this example; however this is not strictly required and the runoff plate may comprise other shapes in other embodiments.

The assembly40includes a pair of side support members, in this example structural beams72and74. The structural beams aligns with and extends along respective sides60and62of the assembly. The structural beams72and74couples to and extends between the accelerator plate68and runoff plate70. The structural beams, accelerator plate and runoff plate form an enclosure76which is rectangular in this example.

Still referring toFIG. 2, the assembly40includes a water intake screen, in this example a Coandă screen78. Referring toFIG. 4, the screen includes a plurality of longitudinally-extending elongate members, as shown by elongate members of numerals80,82and84. The elongate members extend parallel with each other and parallel with a horizontally-extending longitudinal axis85of the assembly40in this example. As seen inFIG. 1, the screen78is positioned between the downstream portion54of the water50and the inlet46of the penstock44. The screen is thus positioned downstream of the dam48and upstream portion52of the water50.

The screen78and elongate members80,82and84extend between and couple to structural beams72and74seen inFIG. 2via welding73in this example. However, this is not strictly required and the elongate members may couple to the structural beams in other manners in other examples, such as via grooves in the structural beams, for example. The elongate members80,82and84, seen inFIG. 3, are thus coupled together and extend between the sides60and62of the assembly40seen inFIG. 2. The screen78and elongate members thereof are also positioned and extend between the accelerator plate68and runoff plate70.

As seen inFIG. 3, each elongate member80is generally wedge-shaped in lateral cross-section in this embodiment. The elongate members taper in a direction extending from the front64towards the rear66of the assembly60in this example; however this is not strictly required and the elongate members need not so taper in other embodiments. Each elongate member80has a first exterior or outer side or surface86aligned with and adjacent to the front of the assembly60. The outer surfaces of the elongate members are outwardly convex in lateral profile in this embodiment. Each elongate member80has a second exterior or inner surface88aligned with and adjacent to the rear66of the assembly60. The inner surfaces of the elongate members are spaced-apart from the outer surfaces86of the elongate members. The inner surfaces88of the elongate members80are narrower than the outer surfaces86of the elongate members in this embodiment.

Still referring toFIG. 3, each elongate member80has a third exterior, top-facing or upstream-facing side or surface90that faces at least in part towards the top56of the assembly. The upstream-facing surfaces are outwardly concave in this embodiment. Each elongate member80has a fourth exterior, bottom-facing or downstream-facing side or surface92that faces at least in part towards the bottom58of the assembly40. The downstream-facing surfaces of the elongate members are spaced-apart from the upstream-facing surfaces of the elongate members. The downstream-facing surfaces92are planar in this example and are sloped in this example relative to a vertical plane79and horizontal plane81.

As seen inFIG. 3, the upstream-facing surfaces90and downstream-facing surfaces92of the elongate members80extend between the respective outer surfaces86and inner surfaces88of the elongate members. The upstream-facing surfaces and downstream-facing surfaces of the elongate members80are wider than the outer surfaces86of the elongate members in this embodiment. The surfaces86,88,90and92of the elongate members extend between the sides60and62of the assembly40seen inFIG. 2.

Referring back toFIG. 3, each elongate member80has an upper or leading edge93between and adjacent outer surface86thereof and upstream-facing surface90thereof. Each elongate member includes an upper peripheral portion95extending between the outer surface86thereof and the upstream-facing surface90thereof. The upper peripheral portion of each elongate member is generally triangular in lateral profile and curved in lateral profile at least in part in this embodiment. In this example the upper peripheral portions95are outwardly convex in lateral profile in part in this example. Referring toFIG. 5, the upper peripheral portions of the elongate members80so shaped may function to direct a flow of water towards an intake direction101and towards the inlet46of the penstock44, between adjacent elongate members80and82.

Referring toFIG. 3, each elongate member80includes a lower peripheral portion99extending between the outer surface86thereof and the downstream-facing surface92thereof. The lower peripheral portion is sloped relative to the upper peripheral portion95of the elongate member in this embodiment. The lower peripheral portion99of the elongate member is curved in lateral profile at least in part and in this example is outwardly concave in part in lateral profile. Referring toFIG. 5, the lower peripheral portions of the elongate members so shaped may function to direct a flow of water towards the intake direction101and towards the inlet46of the penstock44, between adjacent elongate members80and82, before and instead of hitting the leading edge97of the next elongate member82.

Still referring toFIG. 5, the assembly40is positioned to enable water50to flow above and along the outer surfaces86of the elongate members80,82and84, as shown by arrow of numeral87, and to intake portions94and96of the water between adjacent said elongate members80and82, and82and84. The portions of water abut the upstream-facing surfaces90of the elongate members. The elongate members80,82and84are positioned to promote the Coandă effect, with portions94and96of the water50being taken in thereby.

As seen inFIG. 3and in addition without limiting the above, each elongate member80thus may be said to have a three-sided cross section, with an upstream-facing side90, a downstream-facing side92, and an outer side86. The upstream-facing side is outwardly concave, with a circular profile having a radius in the range of 20 mm to 200 mm in one preferred example, with the radius being equal to 100 mm according to one preferred embodiment. The downstream-facing side92is flat. The outer side86is outwardly convex, with a circular profile having a radius in the range of 10 mm to 250 mm, with the radius being equal to 60 mm in one preferred example. However, these ranges and dimensions may not be strictly required and the elongate members80may have other sizes in other embodiments, for example.

As seen inFIG. 3, upstream-facing side90of the elongate member extends downwards from and relative to outer side86of the elongate member by angle α. This angle is measured between the tangent directions of the circular profiles of the upstream-facing side90and the outer side86. Angle α is in the range of 20 degrees to 110 degrees in one preferred example, with the angle α being equal to 65 degrees according to one preferred embodiment. However, these angles may not be strictly required and may have other values in other embodiments, for example. The leading edge93of the elongate member is sharp to promote and improve flow of water thereon and therepast. Rearward edge89and trailing edge91of the elongate member80may be sharp or slightly rounded.

As seen inFIG. 5, the elongate members are arranged in a repeating pattern, with the outer side86of each elongate member roughly parallel to the flow of water50over the screen assembly40as indicated by arrow87.

Referring back toFIG. 4, the assembly40includes a plurality of slots interposed between respective pairs of elongate members, as seen by slot103inFIG. 4. Each slot has a width WSis in the range of 0.1 mm to 10 mm in one preferred example, with the slot width being equal to 1.5 mm according to one preferred embodiment. However, these ranges and dimensions may not be strictly required and may be equal to other values in other embodiments, for example. Referring toFIG. 5, as water flows over the elongate members, surface tension effects cause the water stream to cling to the rounded outer side86of the elongate member and turn towards the slot between the elongate members.

FIGS. 6 to 7show a water intake structure, in this example a Coandă screen assembly40.1for a hydropower plant42.1according to a second embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 1 to 5with the addition of decimal extension “.1”. Assembly40.1and hydropower plant42.1are substantially the same as assembly40and hydropower plant42shown inFIGS. 1 to 5with the following exceptions.

Each elongate member, in this example elongate member80.1has first and second exterior surfaces, in this case an outer surface86.1thereof and a downstream-facing surface92.1thereof which are both planar in this embodiment. The outer surface of each elongate member extends perpendicular with respect to the downstream-facing surface of the elongate member in this example.

As seen inFIG. 7, the outer surfaces86.1and downstream-facing surfaces92.1of the elongate members80.1are sloped in this example relative to the vertical plane79.1and horizontal plane81.1. The outer surfaces of the elongate members are positioned to extend in parallel with the flow of water50.1thereon, with said flow being shown by arrow87.1. Each elongate member80.1has a third exterior surface, in this example an upstream-facing surface90.1which is outwardly concave in lateral profile. The upper peripheral portions95.1of the elongate members are curved in lateral profile at least in part and in this example are outwardly concave in lateral profile in part.

FIGS. 8 to 9show a water intake structure, in this example a Coandă screen assembly40.2for a hydropower plant42.2according to a third embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 1 to 5with the addition of decimal extension “.2”. Assembly40.2and hydropower plant42.2are substantially the same as assembly40and hydropower plant42shown inFIGS. 1 to 5with the following exceptions.

Each elongate member, in this example elongate member80.2is trapezoidal in lateral cross-section in this embodiment. The outer surfaces86.2of the elongate members extend in parallel with the respective inner surfaces88.2of the elongate members in this example. Referring toFIG. 9, the outer surfaces of the elongate members are positioned to extend in parallel with the flow of water50.2thereon, with said flow being shown by arrow87.2. The downstream-facing surfaces92.2of the elongate members80.2are planar in this embodiment.

As seen inFIG. 9, the outer surfaces86.2, inner surfaces88.2and downstream-facing surfaces of the elongate members are sloped in this example relative to the vertical plan79.2and horizontal plane81.2. Referring toFIG. 8, each outer surface86.2of the elongate members80.2has a width WB. The inner surfaces88.2of the elongate members have widths that are equal to or less than 0.5×WBin this embodiment. Each elongate member80.2has an upstream-facing surface90.2that is outwardly concave in this embodiment. As seen inFIG. 9, the upper peripheral portions95.2of the elongate members are curved in lateral profile at least in part and are outwardly concave in lateral profile in part in this example.

FIG. 10shows one of a plurality of elongate members80.3of a water intake structure, in this example a Coandă screen assembly40.3for a hydropower plant42.3according to a fourth embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 8 to 9with the replacement of decimal extension “.2” with decimal extension “.3” and with the addition of decimal extension “.3” for parts not previously having decimal extensions. Assembly40.3and hydropower plant42.3are substantially the same as assembly40.2and hydropower plant42.2shown inFIGS. 8 to 9with the following exception.

The outer surfaces86.3of the elongate members, in this example elongate members80.3, have widths WB.3and inner surfaces88.3of the elongate members have widths that are equal to or less than 0.75×WB.3in this embodiment. The outer surfaces are positioned to extend in parallel with the flow of water50.3thereon, with said flow being shown by arrow87.3. The upper peripheral portions95.3of the elongate members80.3are curved in lateral profile at least in part and in this example are outwardly concave in lateral profile in part.

FIGS. 11 to 13show a water intake structure, in this example a Coandă screen assembly40.4for a hydropower plant42.4according to a fifth embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 8 to 9with the replacement of decimal extension “.2” with decimal extension “.4” and with the addition of decimal extension “.4” for parts not previously having decimal extensions. Assembly40.4and hydropower plant42.4are substantially the same as assembly40.2and hydropower plant42.2shown inFIGS. 8 to 9with the following exception.

As seen inFIG. 13, each of the elongate members, in this example elongate member80.4, has exterior surfaces86.4,88.4,90.4and92.4which form a parallelogram in shape in lateral cross-section in this embodiment. Each of the exterior surfaces of the elongate members is planar in this embodiment. Downstream-facing surface92.4extends parallel to upstream-facing surface90.4and outer surface86.4extends parallel to inner surface88.4of the elongate member in this embodiment. The outer surfaces86.4are positioned to extend in parallel with the flow of water50.4thereon, with said flow being shown by arrow87.4.

Still referring toFIG. 13, upstream-facing surface90.4of elongate member80.4extends downwards from the outer surface86.4of the elongate member at an acute angle α.4relative to the outer surface. Angle α.4is equal to 70 degrees in this example; however this is not strictly required and the angle may be different in other embodiments. Downstream-facing surface92.4of the elongate member extends from the outer surface86.4of the elongate member at an obtuse angle β relative to the outer surface. Angle β is equal to 110 degrees in this example; however this is not strictly required and this angle may be different in other embodiments.

FIGS. 14 to 16show a water intake structure, in this example a Coandă screen assembly40.5for a hydropower plant42.5according to a sixth embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 1 to 5with the addition of decimal extension “.5”. Assembly40.5and hydropower plant42.5are substantially the same as assembly40and hydropower plant42shown inFIGS. 1 to 5with the following exceptions.

Each elongate member, in this example elongate member80.5is generally wedge-shaped in lateral cross-section. Referring toFIG. 16, each elongate member has first and second exterior surfaces, in this example upstream-facing surface90.5and downstream-facing surface92.5, which are planar. The upstream-facing surface extends upwards from the downstream-facing surface at an acute angle ϕ relative to the downstream-facing surface. Angle ϕ is equal to 40 degrees in this example; however this is not strictly required and the angle may be different in other embodiments.

Each elongate member80.5has a third exterior surface, in this example an outer surface86.5which is outwardly convex.

Still referring toFIG. 16, the upper peripheral portions95.5of the elongate members are curved in lateral profile at least in part and in this example are outwardly convex in part in lateral profile. The lower peripheral portions99.5are of the elongate members80.5are sloped relative to the corresponding upper peripheral portions of the elongate members in this embodiment. The lower peripheral portions99.5of the elongate members are curved in lateral profile at least in part and in this example are outwardly convex in part in lateral profile.

FIG. 17shows one of a plurality of elongate members80.6of a water intake structure, in this example a Coandă screen assembly40.6for a hydropower plant42.6according to a seventh embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 14 to 16with the replacement of decimal extension “.5” with decimal extension “.6” and with the addition of decimal extension “.6” for parts not previously having decimal extensions. Assembly40.6and hydropower plant42.6are substantially the same as assembly40.5and hydropower plant42.5shown inFIGS. 14 to 16with the following exception.

Each elongate member, in this example elongate member80.6is generally wedge-shaped in lateral cross-section. Each elongate member has an upper outer surface86.6adjacent to the upstream-facing surface90.6thereof. The upper outer surface is positioned to extend in parallel with the flow of water50.6thereon, with said flow being shown by arrow87.6. Each elongate member80.6has a beveled edge, in this example a lower outer surface98extending between the upper outer surface86.6thereof and a downstream-facing surface92.6thereof. The lower outer surface98is thus adjacent to the downstream-facing surface92.6of the elongate member and is sloped relative to the upper outer surface86.6of the elongate member. Each elongate member80.6in this embodiment thus has a downstream beveled edge.

The upstream-facing surface90.6of each elongate member extends downwards from upper outer surface86.6of the elongate member at an acute angle α.6relative to the upper outer surface86.6of the elongate member. The upstream-facing surface90.6of each elongate member80.6extends upwards from the downstream-facing surface92.6of the elongate member at an acute angle ϕ.6relative to the downstream-facing surface in this example. The lower peripheral portions99.6of the elongate members80.6are sloped relative to the upper peripheral portions95.6of the elongate members in this embodiment.

FIGS. 18 to 21show a water intake structure, in this example a Coandă screen assembly40.7for a hydropower plant42.7according to an eighth embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 1 to 5with the addition of decimal extension “.7”. Assembly40.7and hydropower plant42.7are substantially the same as assembly40and hydropower plant42shown inFIGS. 1 to 5with the following exceptions.

As seen inFIG. 19, each elongate member, in this example elongate member80.7has an outer surface86.7that is outwardly convex in lateral profile. The outer surfaces face towards the front64.7of the assembly40.7in part and face towards the bottom58.7of the assembly in part in this example.

Each elongate member80.7has an upstream-facing surface90.7that is outwardly concave in lateral profile in this embodiment. The outer surfaces86.7of the elongate members are wider than the upstream-facing surfaces of the elongate members and are wider than that the inner surfaces88.7of the elongate members in this example.

As seen inFIG. 21, the inner surfaces of the elongate members80.7are planar and sloped relative to the vertical plane79.7and horizontal plane81.7.

Still referring toFIG. 21, each elongate member82.7includes a top portion100and a bottom portion102. The top portion100of elongate member82.7is adjacent to the bottom portion102′ of an adjacent elongate member80.7.

As seen inFIG. 19, the upper peripheral portions95.7of the elongate members80.7are curved in lateral profile at least in part, outwardly convex in an upper section104thereof and outwardly concave in a lower section106thereof. The lower peripheral portions99.7of the elongate members are sloped relative to the upper peripheral portion95.7of the elongate members in this embodiment. The lower peripheral portions of the elongate members are curved in lateral profile at least in part and in this example are outwardly convex in lateral profile in part.

FIGS. 22 to 25show a water intake structure, in this example a Coandă screen assembly40.8for a hydropower plant42.8according to a ninth embodiment. Like parts have like numbers and functionings as the embodiment shown inFIGS. 18 to 21with decimal extension “.8” replacing decimal extension “.7” and being added for parts not previously having decimal extensions. Assembly40.8and hydropower plant42.8are substantially the same as assembly40.7and hydropower plant42.7shown inFIGS. 1 to 18 to 21with the following exceptions.

As seen inFIG. 22, each elongate member80.8of the assembly includes an inner portion, in this example an elongate mount108that is rigid. The mounts in this example are made of metal, in this case steel plate; however, this is not strictly required and the mounts of the elongate members may be made of other rigid materials in other examples.

The mounts are planar and in the form of rectangular prisms in this example. Each mount108has an upstream-facing surface110and a downstream-facing surface112each of which is planar, substantially similar in size and rectangular in this example. Each mount has a rear114which aligns with the inner surface88.8of the elongate member80.8and which is adjacent bottom58.8of the assembly40.8. Each mount108has a front116spaced-apart from the rear thereof. The upstream-facing surface110and downstream-facing surface112extend between the front and rear of the mount. The front and rear of the mount are substantially the same in shape in this example.

Each mount108includes a pair of sides, as seen by side118inFIG. 22, which extend between the rear114and front116thereof. The rear114, front116and sides118of the mount each have widths WMthat are substantially the same in this example.

As seen inFIG. 23, the assembly40.8includes one or more supports, in this example structural beams72.8and74.8. At least one beam72.8has a plurality of longitudinally spaced-apart grooves120,122and124extending therein from the front or top126thereof towards the rear or bottom128thereof.

Each elongate member80.8is selectively received within a respective said groove120via first or bottom portion122of mount108. The side framing is thus slotted to hold the elongate members in place. The assembly40.8so configured enables selective replacement of only those parts thereof, in this case selective elongate members80.8that wear more significantly over time instead of requiring replacement of the assembly as a whole.

As seen inFIG. 22, each elongate member80.8includes an outer portion, in this example an elongate outer cap125along and upon which water flows. The outer caps are made of an elastomer, in this example rubber, which may provide improved abrasion resistance and be relatively less expensive to manufacture compared to steel for the custom shape of the outer caps. However, this is not strictly required and the outer caps may be made of other materials and be arranged in other configurations in other embodiments.

As seen inFIG. 24, each cap125has a rear or inner surface127and a groove129which extends from the inner surface towards the outer surface86.8of the elongate member80.8.

Alternatively, the outer cap may be made of other polymers, such as a thermoplastic polymer, for example high-density polyethylene (HDPE), which may provide a similar wear performance to steel but with a significant cost saving compared to steel. A further alternatively is to have each elongate member comprise a single integrated and unitary whole, such as an elongate member wholly made of steel.

Referring toFIG. 25, each elongate member80.8has an outer surface86.8with a streamlined shape shaped to gradually alter a path87.8of water50.8extending therealong. The outer surfaces of the elongate members are shaped to promote development of a boundary layer of water thereon and inhibit creation of eddies thereon. As seen inFIG. 22, the outer surfaces86.8of the elongate members80.8are curved at least in part and in this example are outwardly convex.

As seen inFIG. 24, the upstream-facing surfaces90.8of the elongate are curved at least in part and in this example are outwardly concave in part. The outer surface and the upstream-facing surface of each elongate member are thus both curved at least in part in this embodiment. The upstream-facing surface extends downwards from the outer surface86.8thereof at an acute angle α.8relative to the outer surface thereof. The upper peripheral portion95.8of each elongate member80.8is generally triangular in shape in lateral profile in this example.

The lower peripheral portions99.8of the elongate members are outwardly convex in lateral profile in this example, with trailing edges91.8of the elongate members being rounded in this example.

Many advantages may result from the structure of the present invention. The assemblies as herein described, with their elongate members thereof, may comprise improved Coandă screens optimized to take advantage of Coandă and surface-tension effects. The assemblies as herein described, with their elongate members thereof, may function to: increase water intake capacity per unit area of screen; decrease elongate member profile erosion by sediment; decrease sensitivity to elongate member profile erosion by sediment; decrease sensitivity to plugging by organic material; and/or increase self-cleaning capabilities.

The assemblies herein described use the Coandă effect on the scale of the individual elongate members as opposed to slicing the fluid.

One of the primary structural differences between the assemblies as herein described and the known prior art is that the assemblies as herein described may use surface-tension effects or the Coandă effect to begin redirecting the water as it flows over the top of each elongate member, and not rely solely on the leading edge of the elongate member to turn the water flow. This may allow the leading edge of each elongate member to be effectively hidden behind the furthest protrusion of the next upstream elongate member into the water flow, deflecting rocks, sand, and organic debris away from the sharp edge of the screen. This may function to reduce wear on the leading edge of each elongate member and reduce the amount of organic debris that catches between the elongate members and plugs up the screen.

The structures as herein described may result in improved durability by using the stickiness of fully developed flow as opposed to prior art systems which slice undeveloped flow. This may result in the structures as herein described being less reliant on the sharpness of the leading edge of the screen profile. Since the leading edge may erode over time due to sediment, this may result in structures as herein described which are more long-lasting.

It will be appreciated that many elongate member design variations are possible within the scope of the invention described herein.

It should also be noted that the intake screen is not only applicable to hydropower plants, but can also be applied to any form of water intake structure such as a drinking water intake, cooling water intake, or industrial process water intake, for example.

ADDITIONAL DESCRIPTION

Examples of water intake structures have been described. The following clauses are offered as further description.(1) A water intake structure comprising: a plurality of elongate members, the elongate members coupling together and being trapezoidal in lateral cross-section.(2) The structure of clause 1 wherein exterior surfaces of the elongate members form parallelograms in shape in lateral cross-section.(3) The structure of clause 1 wherein each said elongate member has at least one exterior surface that is outwardly concave.(4) The structure of any one of clauses 1 to 2, wherein each said elongate member has an outer surface and an upstream-facing surface, the upstream-facing surface extending from the outer surface at an acute angle relative to the outer surface.(5) The structure of clause 4 wherein each said outer surface is planar.(6) The structure of clause 5 wherein each said upstream-facing surface is planar.(7) The structure of any one of clauses 4 to 5 wherein each said upstream-facing surface is outwardly concave.(8) The structure of any one of clauses 4 to 7 wherein the structure is positioned to enable water to flow above and along the outer surfaces of the elongate members, and to intake a portion of said water between adjacent said elongate members, with said portion of said water abutting said upstream-facing surfaces of the elongate members.(9) The structure of any one of clauses 1 to 8 wherein each said elongate member has an inner surface that is planar and a downstream-facing surface that is planar.(10) The structure of any one of clauses 4 to 6 wherein each said elongate member has a downstream-facing surface that extends in parallel with the upstream-facing surface thereof.(11) The structure of any one of clauses 4 to 8 wherein each said elongate member has an inner surface that extends in parallel with the outer surface thereof.(12) A water intake structure comprising: a plurality of elongate members, the elongate members coupling together and each said elongate member having first and second exterior surfaces that are planar and a third exterior surface that is outwardly concave.(13) The structure of clause 12 wherein the third exterior surfaces are outer surfaces of the elongate members.(14) The structure of any one of clauses 12 to 13 wherein the second exterior surface extends from the first exterior surface at an acute angle relative to the second exterior surface.(15) The structure of any one of clauses 12 to 14 wherein each said elongate member is wedge-shaped in lateral cross-section.(16) The structure of clause 12 wherein the third exterior surfaces are upstream-facing surfaces of the elongate members.(17) The structure of any one of clauses 12 and 16, wherein each said second exterior surface extends perpendicular from its corresponding said first exterior surface.(18) The structure of any one of clauses 12 and 16 to 17 wherein the first exterior surfaces are outer surfaces of the elongate members and the second exterior surfaces of the elongate members are downstream-facing surfaces of the elongate members.(19) The structure of any one of clauses 13 and 18 wherein the structure is positioned to enable water to flow above and along the outer surfaces of the elongate members, and to intake a portion of said water between adjacent said elongate members, with said portion of said water abutting the upstream-facing surfaces of the elongate members.(20) A water intake structure comprising: a plurality of elongate members, the elongate members coupling together and each said elongate member having an outer surface, an upstream-facing surface, and a downstream-facing surface, with the upstream-facing surface thereof extending from the outer surface thereof at an acute angle relative to the outer surface thereof, and with a beveled edge extending between the outer surface thereof and the downstream-facing surface thereof.(21) A water intake structure comprising: a plurality of elongate members, the elongate members coupling together and each said elongate member being wedge-shaped in lateral cross-section, with an outer surface thereof positioned to extend in parallel with a flow of water thereon, and with each said elongate member having a downstream beveled edge.(22) The structure of any one of clauses 20 to 21 wherein the structure is positioned to enable water to flow above and along the outer surfaces of the elongate members, and to intake a portion of said water between adjacent said elongate members, with said portion of said water abutting the upstream-facing surfaces of the elongate members.(23) A water intake structure comprising: a plurality of elongate members, the elongate members coupling together and each said elongate member having an outer surface that is outwardly convex and an upstream-facing surface that is outwardly concave.(24) The structure of clause 23 wherein each said elongate member is generally wedge-shaped in lateral cross-section.(25) The structure of clause 23 wherein the upstream-facing surfaces of the elongate members are wider than the outer surfaces of the elongate members.(26) The structure of clause 23 wherein the outer surfaces of the elongate members are wider than the upstream-facing surfaces of the elongate members.(27) The structure of any one of clauses 23 to 26, wherein each said elongate member has an inner surface that is planar.(28) The structure of clause 27 wherein the inner surfaces of the elongate members are sloped.(29) The structure of any one of clauses 23 and 26, wherein each said elongate member includes a top portion and a bottom portion, with each said top portion being adjacent to the bottom portion of an adjacent said elongate member.(30) A water intake structure comprising: a plurality of elongate members, the elongate members coupling together and each said elongate member having an outer surface aligned with a front of the structure, having a downstream-facing surface facing a bottom of the structure, and including a lower peripheral portion extending between the outer surface thereof and the downstream-facing surface thereof, the lower peripheral portion being curved in lateral profile at least in part.(31) A water intake structure comprising: a plurality of elongate members, the elongate members coupling together and each said elongate member having an outer surface aligned with a front of the structure, having an upstream-facing surface facing a top of the structure, having a downstream-facing surface facing a bottom of the structure, an upper peripheral portion extending between the outer surface thereof and including a lower peripheral portion extending between the outer surface thereof and the downstream-facing surface thereof, the lower peripheral portion being sloped relative to the upper peripheral portion thereof.(32) The structure of any one of clauses 1 to 31, wherein each said elongate member is a bar.(33) The structure of any one of clauses 1 to 32, wherein the elongate members are positioned to promote the Coandă effect, with portions of the water being taken in thereby.(34) The structure of any one of clauses 1 to 33, wherein the structure is a Coandă screen.(35) In combination, a penstock having an inlet, and the structure of any one of clauses 1 to 34, the structure being positioned between the water to be taken in and the inlet of the penstock.(36) In combination, a hydropower plant and the structure of any one of clauses 1 to 34.

It will be understood by someone skilled in the art that many of the details provided above are by way of example only and are not intended to limit the scope of the invention which is to be determined with reference to the following claims.