WO2012120096A1 - Device and method for creating a hydraulic jump, in particular for a fountain or swimming pool - Google Patents

Abstract

A hydraulic jump (1) is created at the free surface (2) of a liquid that is made to flow over a surface (23) that drops towards an outlet region for the liquid, the supply being brought about by a supply system (3) overflowing, an element (24) rising above the flow surface (23) so as to form a retention space (27) for the liquid before it is discharged. The liquid can be recycled. The jump (1) can be stable or not stable. The invention can be applied to the creation of artificial waves for simulation devices, ornamental fountains or swimming pools.

Description

 DEVICE AND METHOD FOR CREATING A HYDRAULIC RESS, ESPECIALLY FOUNTAIN OR SWIMMING POOL

DESCRIPTION

TECHNICAL AREA

The subject of this invention is a device and a method for creating a hydraulic jump; or, more generally, creating a fluid jump, since the jump phenomenon is not limited to liquids and can be applied also to heavy gases in a lighter atmosphere. The device could then be for decorative use as wave simulations or scientific to perform certain experiments. Fountains and pools can be cited as concrete applications.

 A hydraulic jump is a sudden change in level of the free surface of a liquid (or even a gas). It corresponds to a sudden transition from a high-speed flow regime to a subcritical regime.

GENERAL SUMMARY OF THE INVENTION

 The invention makes it possible to create such a projection with a very simple device.

Particular objects of the invention are the mastery of the parameters that make it possible to adjust the characteristics of the projection, as well as particular means contributing to favorable embodiments of the device. The phenomenon of hydraulic jump is already known, but the conditions in which it is produced generally consist in allowing a liquid trickle of sufficient height to flow on a horizontal surface: a rise in the level of the liquid at a given radius is then observed. from the point of fall of the liquid. Such devices and methods appear to be practicable only on a very small scale, otherwise the flow rate and the drop height required to produce a sufficient charge in the liquid or a jumper of significant dimensions should be quite excessive. They also do not lend themselves to an adjustment of the parameters of the projection.

 It should be added that non-circular projections, polygonal or lobed, for example, a few centimeters in diameter, have also been obtained by subjecting the flow to particular conditions, in particular by allowing it to first flow in a pipe whose Bottom end was a nozzle: the shape of the projection depended on the nozzle diameter of the nozzle. However, it was found that these forms were often unstable, and that they also depended on the surface tension of the liquid, which limits these phenomena to centimeter-sized installations. It is also apparent that such nozzle devices do not readily lend themselves to adjustments in flow conditions and surge parameters.

It is also known that hydraulic jumps appear at the junction of torrential flows and fluvial flows in nature or downstream of dams. The projections observed then are normally turbulent, unstable, irregular in shape, and particularly rich in air bubbles: they therefore have no decorative value and only lend themselves exceptionally to recreational applications, such as surfing on the sea. tidal bore during high tides. The setting of their parameters is hardly conceivable.

 Some installations of the prior art also making it possible to create a hydraulic jump (US Pat. Nos. 5,044,554, WO-A-2004 / 076,779 or WO-A-93/15801), but with divergent or linear flows as before. . It appears that the characteristics of the projection are then difficult to adjust or modify.

 The use of the invention, on the other hand, will make it possible to easily obtain hydraulic projections having desired characteristics of shape, dimensions and stability, and to easily adjust these characteristics, in particular so as to change their shape, by changing from one form to another. regular, circular for example, irregular, polygonal for example, or vice versa, and a stable jump to an unstable jump or vice versa.

In a general form, the invention relates to a device for creating a hydraulic jump, comprising a bottom surface that can be occupied by a circulating fluid, the bottom surface extending between a fluid inlet region and a fluid outlet region and lowering from the inlet region to the exit region, and further comprising a wall joined to the bottom surface at the the fluid outlet region extending above the bottom surface and provided with an upper fluid overflow edge, and a fluid discharge member separated from the bottom surface by the wall; the device can be, among other applications, a fountain or a swimming pool; when the bottom surface is occupied by a circulating fluid, the projection occurs in particular between the inlet region and the outlet region. Depending on the circumstances, the jump may be stable (immobile in the device) or not. In the case where it is unstable, its position is generally oscillating or periodic in the device.

 An essential feature of the invention is that the device allows the establishment of a convergent flow of fluid from the inlet region to the exit region.

Only a convergent device makes it possible to animate the hydraulic jump by rendering it mobile or unstable in the extent of the device by means of an oscillating movement. The originality of the invention is based on the ability to control the stable or oscillatory nature of the non-axisymmetric movements of the jump and the frequency of the oscillations by an appropriate choice of the shape of the flow surface and by the choice of flow. It should be emphasized that the oscillation of the projection does not come from oscillations of the flow itself, but from a phenomenon of non-radial instability, which is only triggered in a constant flow convergent flow. The jump naturally loses its circular shape in favor of scalloped forms, as will be represented and of which an example is a heart shape rotating cyclically. The instability of the jump is obviously valuable for certain activities, for example some leisure activities such as surfing. Convergent flow thus represents much more than an alternative embodiment of existing installations with divergent or linear flow.

 In a frequent situation, the device is annular, the fluid outlet region being surrounded by the input region, both circular: the projection is then a circular line. This definition, however, should not be heard too strictly, since regions in irregular circles, elliptical for example, give similar results, as well as regions that are not closed but extending only to portions of circles for example: the characteristic that it is desirable to introduce is a convergent flow favoring the creation of a jump of considerable height over a region of width that is small or much smaller than the width of the region of entry of the fluid, with faculties of adjust the characteristics of the jump more easily.

The function of the input region is to provide the fluid at a sufficient rate and speed. This velocity can be acquired by gravity when the inlet region is formed by a second wall, joined to the bottom surface, extending above the bottom surface and provided with an upper edge of overflow of the fluid, and an element introducing the fluid separated from the bottom surface by the second wall.

 The inlet region may also be produced by a slit extending above the bottom surface, but possibly at a low altitude, and the fluid energy is then acquired by restricting the flow under pressure at through the slot.

 One of the means for adjusting the characteristics of the flow, in order to adjust those of the projection, can then consist in that an upper plate delimits the slot forming an upper limit of the slot, the device further comprising means for adjusting the height of the top plate and thickness of the slot.

 The bottom surface will often have an increasing slope from the fluid inlet region to the fluid outlet region, for example a height hyperbolic function as a function of a position between the fluid inlet region and the fluid inlet region. fluid outlet.

 The device can operate in a closed circuit, comprising a pump and extending between the liquid outlet region and the liquid inlet region. The pump will then be advantageously adjustable in order to adjust the flow rate of the liquid.

In the frequent case of a device of great width, where the projection will extend over a long length, it will often be sought to equalize the flow rate on a regular line at a constant distance between the inlet region and the fluid outlet. But the closed circuit will generally be composed of pipes leading to discrete locations of the fluid inlet region; but the flow may nevertheless be standardized by means of a flow distribution bed constructed of porous material in front of which the pipes will emerge.

 In other circumstances, an irregularly shaped jump will be sought. One way to achieve this will be to have obstacles discretely in some places in the direction of the width of the device so as to intercept separate portions of the fluid flow and thus create irregularities in the flow.

 In some cases, it will be sought to give the injected fluid a transverse velocity component, for example to induce a rotational movement if the injection is annular. Guiding rudders consisting of vertical plates, arranged throughout the inlet region, can be oriented to adjust spatially and temporarily the direction of the injected fluid.

 Particular obstacles will consist in variations in the height of the upper plate in the case where the region of entry of the fluid is a slot: the upper plate will then be flexible, and the means for adjusting its height will comprise a plurality of distinct means which will be adjustable independently.

Other ways to adjust the characteristics of the jump will be to build the device in separate mutually mobile parts: this is how the wall can be mobile vertically relative to the bottom surface, and similarly, the fluid inlet region may belong to a movable part vertically relative to the bottom surface, to adjust its height.

 The invention further relates to a method for creating a hydraulic jump, comprising pouring a fluid on an upper portion of an inclined surface, at a flow rate greater than a threshold, to create a flow on the inclined surface, and to create a retention of a volume of the fluid at a lower part of the inclined surface. The flow is convergent on the inclined surface, the upper part of which is wider than the lower part.

 The jump may be stationary or unstable, as already mentioned. In the latter case, with an annular inclined surface, the projection may consist of a closed line, eccentric with respect to the inclined surface, and rotating.

 Other details and features of the invention will now be described with reference to the figures, which are given by way of illustration, in order to completely represent certain possible embodiments of the invention. LIST OF FIGURES

Figures 1 and 2 show a first embodiment of the invention in diametral section and top view; Figures 3 and 4 show two possible forms of projection; Figures 5, 6, 7, 8 and 9 show a second embodiment of the invention, with two variants; Figure 10 illustrates a particular application of the invention; Figure 11 illustrates another embodiment of the invention; and Figures 12, 13 and 14 illustrate flow deflection devices.

DESCRIPTION OF PREFERRED EMBODIMENTS

 A first embodiment is shown in Figure 1. The device is seen in diametral section and its shape is circular. It is composed of four main elements, namely a liquid, a liquid inlet element, a liquid flow surface and a liquid discharge element. Optional elements are a liquid reservoir, a liquid distribution circuit, and a pump. The liquid flows from the injection element to the discharge element on the flow surface forming a projection (1), that is to say a sudden rise in the level of the free surface ( 2).

The input element (3) comprises a bottom (4), concentric walls (5 and 6), and an upper plate (7) which define a circular trench (8) occupied by the liquid. The upper plate (7) is fixed to the outer wall (5) sealingly by a silicone seal (9). It extends a little above the inner wall (6) forming a slot (10) circular. It is deformable and can be pressed downwards by the rotation of a number of threaded rods (11) retained in captive brackets (12) suspended from threaded rods (13) embedded in the outer wall (5). . Pressing the top plate (7) produces a decreasing the thickness of the slot (10) and, at equal flow rate of the liquid, an increase in its speed. The bottom of the trench (8) comprises, spread on a grid (14), a lower bed (15) of clay balls and an upper bed (16) of gravel, which serve to distribute the flow of fluid on the periphery of the slot (10). The distribution circuit (17) in fact comprises a first pipe (18) originating from the reservoir (19) and ending in the pump (20), and distribution pipes (21) leaving the pump (20) and resulting in faucet nose (22) distributed across the bottom plate (4) but in too small number to provide a sufficiently uniform flow through the slot (10) without passing through the porous material beds (15 and 16).

The flow surface (23) is lowered from the slot (10) to the liquid outlet member (524), which consists of a tube (25) disposed through a central hole in the surface outlet (23) and which is located above the tank (19), which is open. The tube (25) is joined to the flow surface (23) rising above it and thus forms a circular wall (26) creating a retention volume (27) of the convergent flow. The liquid thus flows on the flow surface (23) of an inlet region (the slit 10) to an outlet region (the upper edge 28) which are concentric, accumulates in the retention volume (27). ), and the antagonism between the liquid flowing and the liquid retained is the cause of the jump (1); then the liquid leaves the flow surface (23) overflowing the upper edge (28) of the tube (26) and falling into the tube (26) and into the reservoir (19), where it is recycled by the distribution circuit (17).

 Figure 2 is a top view of the device, which shows the circular or annular nature of the main elements. The pressing means, including the threaded rods (11), of the upper plate (7) are however discrete, sixteen in number in this embodiment.

 With the exception of an outer flat portion (29) connecting to the top of the inner partition (6) and delimiting the slot (10), the flow surface (23) has a hyperbolic shape whose height Z is inversely proportional to the radius R to a constant (Z = AB / R).

 The characteristics of the projection depend on the geometrical characteristics of the device and the flow, in particular the flow rate. If we call H the depth of the flow at a determined radius R, the velocity of the waves whose wavelength is large relative to the depth is expressed by

C = fciiH),

 where g is the gravity constant, the flow rate

 Q = InRHu

 where v is the speed of the flow of the liquid

 and the Froude number is equal to

Fr = I v I / c. The appearance of the hydraulic jump (1) requires that the injected liquid reaches a speed greater than that of the waves, or that the Froude number is greater than 1. The height of the jump is defined by the heights H1 and H2 other of the jump, by the formula

H ₂ _ (1 + 8 ^ ² ) ² - 1 where Fr i is the number of froude at the point of jump. Depth Ηχ can be written

Q

 H

2 ^ Rj (gH _pot y where H. (free falling height corresponding local velocity) and Rj is the radius of the jump (1) The characteristic period of the oscillations of the unstable projection (1) can be approximated by

^R j ^{~ r} or,

where r _out is the outside radius of the flow surface (23), at the slot (10), and v ₂ is the velocity of the liquid downstream of the projection (1), that is

R:

 'adv

 H

Q flow must be greater than The behavior of the jump (1) changes according to the value of the Froude Fr number and can be chosen according to the desired characteristics:

 from 1.7 to 2.5, the projection is weak and laminar;

 - from 2.5 to 4.5, it is transient and generates small waves;

 - from 4.5 to 9, it is balanced and stationary; - above 9, it is irregular and generates waves, splashes and bubbles.

 The following approximate formulas may also be used:

Q

3 _

R ² H ⁴

 adv ^ 1 '

In terms of speed, with the criterion Fr> 1 in the earth's gravity field, we can observe the hydraulic jump (1) for a flow of fluid satisfying the relation v ² / h> 10m / s ² at the injection, where v therefore represents the speed of the liquid through the slot (10) and h the height thereof. It has also been observed that the diameter of the hydraulic jump (1) is even greater than the height of the wall (26) is important. Similarly, a flow surface (23) which is very hollow towards the center, thus having a large retention volume (27), leads to a longer oscillation time of the projection (1) than an almost flat surface. The convergent flows therefore have the advantage of giving this greater stability with a reduced retention volume (27), since it extends over a smaller circle than with other flows.

 When the projection (1) is not stationary, beyond a critical value of the flow, it takes in this embodiment the appearance (Figure 3) of a continuous line substantially circular but eccentric axis of the device and which moves by rotating in the angular direction of the flow surface (23), so that each location thereof regularly sees the projection (1) go up and down, except the extreme rays. It is also possible (FIG. 4) to create non-circular projections (1), by modifying the characteristics of the flow by local obstacles which break its uniformity: if, for example, the upper plate (7) has a flexibility, the slot (10) may be narrower under the threaded rods (11) than between them, which produces variations in the spoke radius (1) and a star pattern.

Another embodiment will now be described by means of FIGS. 5 to 9. It comprises two caps that are nested one inside the other, of approximately hemispherical shape with a concavity oriented downwards. An outer cap (30) rests on a base (31). An inner cap (32) encloses the reservoir, now (33), and supports the flow device (34) and the liquid discharge member (35). A pump (36) is disposed in the reservoir (33) and delivers the liquid that has fallen into the circular volume (37) intermediate to the caps (30 and 32), where it rises.

The top of the inner cap (32) is joined to a flange (38) that forms the fluid inlet member and extends above the flow surface (34). The excess liquid overflows from the flange (38) and reaches the flow surface (34) at a rate dependent on the overhang height of the flange (38). The characteristics of the flow and the projection (1) on the flow surface (34) are unchanged and depend on the same parameters as in the previous embodiment. An advantage of the present mode is that it is simple in form and construction. Another advantage is that the height of the rim (38) with respect to the flow area (34), and hence the speed of arrival of the liquid can be adjusted. In the embodiment of FIGS. 6 and 7, where the caps (30 and 32) are at invariable positions guaranteed by spacers (39), the rim (38) is screwed to the outside of the inner cap (32) and motors (40) adjust the height of the rim (38) by acting on vertical racks (41) established on the inner surface of the rim (38), below the flow surface (34), by pinions training not shown; seals (60) and (61) are disposed outside the surface the flow (34) facing the flange (38) and rubbing against it, and around the transmission (62) arranged at the output of the motors (40) and through the inner cap (32), which raises or lowers the flange (38) between the states of Figures 6 and 7. In the embodiment of Figures 8 and 9, spacers (42) connect the flange (38) to the outer cap (30), and this is the height of the inner cap (32) which varies under the rotation of the motor (40). The same effect of varying the height of the flange (38) with respect to the flow surface (34) is obtained.

Figure 10 shows the possible application of the invention to a pool dug entirely in the ground. The funnel-shaped flow surface (43) is surrounded by a circular pit (44) where water is recycled from pump-equipped conduits (45) radiating from a central well (47) which corresponds to the liquid discharging element and at a short distance from which the flow surface (43) stops. The conduits (45) open into the circular pit (44), and the recycled water rises up to overflow and flow into the flow surface (43) as before. A central platform (48) covers the well (47), and protective threads (49) stretched between the platform (48) and the flow surface (43) complete to separate the swimmers from the hole well (47). The platform (48) is suspended from an arrow-shaped gangway (50) through which bathers access or exit the pool. Access may possibly be possible directly through the outside of the surface (43) which then acts as a toboggan.

 Some other optional features of the invention will now be described. FIG. 11, which is a view from above of a device similar to that of FIGS. 1 to 4 for example, shows that a convergent flow can be achieved with an input element 3 that is both elliptical and extending over a sector of a circle, the discharge element (24) also extending over a sector of a circle and both being limited by an angle-shaped vertical wall (63) which gives two lateral limits to the device and flow. The projection (1) is again in the form of a continuous line, here more or less elliptical, surrounding the discharge element (24) of one side of the vertical wall (63) to another. The other characteristics of the process are not really modified.

Other characteristics of the flow and the projection can be modified by introducing an angular velocity component to the flow of fluid by rudders placed at the inlet region of the liquid. These rudders are particularly well suited to the configuration at the slot (10) of Figures 1 to 4, through which the initial speed of the fuide is important. The rudders consist of panels distributed regularly around the circumference of the input element (3) and movable, generally in unison, around vertical axes by means of motors (59). However, special provisions must be made when the slot (10) has a variable height: this is shown in the following figures.

 A somewhat different embodiment is described in the means of Figures 12, 13 and 14. The rudders (75) comprise horizontally oriented rectangular panels, movable in translation only. There is a single panel (76) and a hollow panel (77) in which the previous slide. In addition, the panels (76) and (77) are alternately fixed to the upper axis (65) and the lower axis (66) to limit the irregularities of flow due to their different thicknesses. The panels (76) and (77) are fixed to the pins (65) and (66) rigidly, their main edges are horizontal and their extreme edges are adjacent to the top plate (7) and the flow surface (23). . The hollow panels (77) are thicker near the axis to which they are attached in order to have sufficient stiffness but thinner toward the solid panels (76); all of the panels (76) and (77) also taper toward the flow of fluid away from the axes (65) and (66), as seen in Figure 14, so as not to disturb the flow to excess. Such a device could be generalized to a larger number of panels arranged in a telescopic arrangement and sliding on one another (linked to their neighbors by vertical rails for example), the two ends of the arrangement being fixed to the axes ( 65) and (66).

Claims

A device for creating a hydraulic projection (1) comprising a flow surface occupied by a circulating fluid, the flow surface (23, 24) extending between a fluid inlet region and a fluid flow region fluid outlet region and lowering from the inlet region to the outlet region, and further including a wall (26) joined to the flow surface at the outlet region of the fluid, extending above of the flow surface and provided with an upper fluid overflow edge, and a fluid discharge member (24) separated from the flow surface by the wall, characterized in that the flow surface, the fluid inlet region, the fluid outlet region and the wall are concentric, the fluid inlet region surrounding the fluid outlet region. 2. Device for creating a hydraulic jump according to claim 1, wherein the inlet region is formed by a second wall (38), joined to the flow surface, extending above the surface of flow and provided with an upper fluid overflow edge, and a fluid introduction member separated from the flow surface by the second wall. The hydraulic jump generating device according to claim 1, wherein the fluid inlet region is a slot (10) extending above the flow surface. 4. Device for creating a hydraulic jump according to claim 3, wherein an upper plate (7) defines the slot forming an upper limit of the slot, the device further comprising means for adjusting the height of the upper plate, and thick of the slit. A hydraulic jump generating device according to claim 1, wherein the flow surface has an increasing slope from the fluid inlet region to the fluid outlet region. The hydraulic jump generating device according to claim 5, wherein the flow surface follows a hyperbolic height function as a function of a position between the fluid inlet region and the fluid outlet region. The hydraulic jump generating device according to claim 1, comprising a fluid closed circuit, comprising a pump (20, 36), between the fluid outlet region and the fluid inlet region. 8. A device for creating a hydraulic jump according to claim 1, comprising means for adjusting the flow rate of the fluid. 9. Device for creating a hydraulic jump according to claim 7, wherein the closed circuit comprises pipes (21) opening into the inlet region of the fluid, and the inlet region of the fluid comprises a bed (15, 16) for distributing the flow of porous material in front of which the pipes open. A hydraulic jump generating device as claimed in claim 1, including obstacles to the fluid extending in certain locations in a width direction of the device so as to intercept separate fluid flow positions. 11. Device for creating a hydraulic jump according to claim 4, wherein the upper plate (7) is flexible and the height adjustment means comprise a plurality of independently adjustable means (11). 12. A device for creating a hydraulic jump according to claim 1, wherein the wall (26) is vertically movable relative to the flow surface. 13. A device for creating a hydraulic jump according to claim 1, wherein the fluid inlet region belongs to a moving part vertically with respect to the flow surface. 14. A device for creating a hydraulic jump according to claim 1, wherein the flow surface (23), the inlet region of the liquid, the outlet region of the liquid and the wall extend over sectors of the tower. , stopping at a wall (63) shaped angle. 15. Device for creating a hydraulic jump according to claim 1, comprising means for adjusting the direction of the fluid, arranged at the inlet region of the fluid. 16. A device for creating a hydraulic jump according to claim 15, wherein the fluid direction adjustment means are rudders (75) each pivoting about a vertical axis and distributed along the inlet region of the fluid. . 17. Device for creating a hydraulic jump according to claim 4, comprising means for adjusting the direction of the fluid, arranged at the inlet region of the fluid, where the fluid direction adjustment means are rudders (75). each pivoting about a vertical axis and distributed along the inlet region of the fluid, and the vertical axis comprises two separate portions (65, 66) engaged through the top plate (7) and the flow surface (23) respectively, and the rudder further comprises mutually useful panels respectively depending on the parts of the axis. 18. Device for creating a hydraulic jump according to claim 17, wherein the panels are arranged in a telescopic assembly having ends (76, 77), respectively fixed to the parts of the axis, and slide on each other. 19. Device for creating a hydraulic jump according to any one of the preceding claims, characterized in that it is a swimming pool. 20. Device for creating a hydraulic jump according to any one of claims 1 to 18, characterized in that it is a fountain. A method of creating a hydraulic jump consisting of pouring a fluid on an upper portion of an inclined surface at a flow rate greater than a threshold, creating a flow on the inclined surface, and creating a retention of a volume of the fluid at a lower part of the inclined surface, characterized in that the flow is convergent on the inclined surface, the upper part of which is wider than the lower part. 22. A method of creating a hydraulic jump according to claim 21, wherein the jump (1) is stationary. 23. The method of creating a hydraulic jump according to claim 21, wherein the projection (1) is unstable. 24. The method of creating a hydraulic jump according to claim 21, wherein the inclined surface is annular and the projection is a closed line, eccentric with respect to the inclined surface, and rotating.