Auxiliary energy dissipater for improving energy dissipation effect of sudden expansion drop sill stilling pool

Abstract

The invention discloses an auxiliary energy dissipater for improving the energy dissipation effect of a sudden-expansion drop sill stilling pool, and belongs to the technical field of high-speed water flow flood discharge and energy dissipation. A shunting middle pier and two side piers are arranged in the falling stilling pool along the water flow direction; the two side piers are arranged on the two side walls of the drop-cutting stilling pool respectively, and two symmetrical discharge grooves are formed by the two side piers and the diversion middle pier. Water flow passing through the submersible perforation hole forms two strands of longitudinally stretched water flow in the two discharge grooves. According to the auxiliary energy dissipater for improving the energy dissipation effect of the sudden-expansion drop sill stilling pool, the problems that in the prior art, a sudden-expansion drop sill stilling pool is unstable in flow state, large in wave, low in energy dissipation rate and the like can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-speed water flow flood discharge and energy dissipation. Specifically, it relates to an auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion drop sill energy dissipation basin. BACKGROUND

[0002] Bottom flow energy dissipation, as a common energy dissipation method, is widely used in the field of flood discharge and energy dissipation in water conservancy projects. Bottom flow energy dissipation forms a hydraulic jump in the energy dissipation basin to cause strong shear and rolling of the water flow, thereby reducing the energy of the water flow, and further ensuring the smooth connection of the discharged water flow with the downstream river flow and the safety of the flood discharge facilities. The inflow velocity of a conventional energy dissipation basin is generally controlled within 25 m / s. When the inflow velocity is 30-40 m / s, it is not very economical to use a conventional energy dissipation basin for energy dissipation. Thus, a drop sill energy dissipation basin, a special form of bottom flow energy dissipation, is derived. The drop sill at the inlet of the energy dissipation basin can effectively reduce the near-bottom velocity of the energy dissipation basin and reduce the fluctuating pressure of the water flow on the bottom plate of the energy dissipation basin. Due to the large inflow velocity, the drop sill is arranged at the bottom of the inlet of the energy dissipation basin, and the two sides of the submerged jet orifice are arranged in a sudden expansion form to prevent the sidewalls of the energy dissipation basin from being damaged by high-speed water flow cavitation. Since the high-speed submerged jet main flow enters the drop sill energy dissipation basin in the middle of the water body, two horizontal axis rolling energy dissipations are formed above and below the main flow, which is different from the traditional energy dissipation basin which only has one horizontal axis rolling energy dissipation on the upper surface. This is also the reason why the flow pattern of a general drop sill energy dissipation basin is not very stable and the wave is large, and thus the energy dissipation rate is relatively low. SUMMARY

[0003] The purpose of the present application is to provide an auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion drop sill energy dissipation basin to solve the problems of unstable flow pattern, large wave, and low energy dissipation rate of the sudden expansion drop sill energy dissipation basin in the prior art. To achieve the above purpose, the present application provides the following technical solutions: An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion drop sill energy dissipation basin, wherein one end wall of the drop sill energy dissipation basin is provided with a submerged jet orifice; a flow dividing middle pier and two side piers are arranged in the drop sill energy dissipation basin along the water flow direction; the two side piers are arranged on the two sidewalls of the drop sill energy dissipation basin respectively, and form two symmetrical discharge channels with the flow dividing middle pier; the water flow passing through the submerged jet orifice forms two longitudinally stretched water flows in the two discharge channels.

[0004] Further, the center axis of the flow dividing middle pier coincides with the center axis of the submerged jet orifice.

[0005] Further, the pier head height of the flow dividing middle pier is H 1 flush with the top of the submerged jet orifice.

[0006] Further, the pier head height of the two side piers is H 1 flush with the top of the submerged jet orifice.

[0007] Furthermore, the heads of the diversion pier and the side pier are positioned downstream of the submerged perforation opening. L 1 = (1.5 ~ 2.0) d Among them d It is the larger of the diameter of the submersible orifice or the length and width of the rectangular outlet.

[0008] Furthermore, the length of the diversion pier L = (2.0~3.0) H 1.

[0009] Furthermore, the length of the side pier L = (2.0~3.0) H 1.

[0010] Furthermore, the top surface of the diversion pier and the side pier is a sloping surface that rises along the flow path, and the angle between the sloping surface and the horizontal plane is 30°~40°.

[0011] Furthermore, the contraction angle between the discharge channel and the side wall of the stilling basin... α The angle is 8°~12°, and the width of the tail of the pier is... b = L ×tan( α The width of the tail of the pier in the diversion is 2. b .

[0012] Furthermore, the outlet shrinkage ratio of the discharge channel ε = B 2 / B 1 is 0.4~0.5, of which B 1 represents the width of the drain inlet. B 2 represents the width of the discharge channel outlet.

[0013] The beneficial effects of this invention are: This invention discloses an auxiliary energy dissipation structure to improve the energy dissipation effect of a sudden expansion sloping stilling basin. By setting up a diversion pier and two side piers, in one engineering embodiment, the energy dissipation rate of the stilling basin in the prior art is increased from 58% to 80%, which is a significant improvement. In the prior art, to achieve an energy dissipation rate of 80%, the length of the stilling basin must be extended by 30m, which is an extension rate of about 20%. This invention can effectively improve the flood discharge energy dissipation characteristics of the sloping stilling basin, shorten the length of the stilling basin, and reduce the engineering construction cost. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural schematic diagram of the present invention; Figure 2 This is a schematic diagram of the geometric parameters of the present invention. Figure 3This is a schematic diagram of the three-dimensional geometric parameters of the present invention; Figure 4 This is a comparison of the water surface line in the underwater stilling basin in Example 1. Figure 5 It is a velocity distribution cloud map obtained from the original stilling basin through numerical simulation calculation; Figure 6 This is the flow velocity distribution cloud map obtained by numerical simulation calculation in Example 1; In the attached diagram: 1. Side pier; 2. Diversion pier; 3. Submerged jet orifice; 4. Stilling basin. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0016] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0018] In the description of this invention, "a plurality of" means two or more.

[0019] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0020] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0021] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0022] Example 1 See attached Figures 1-6 This embodiment discloses an auxiliary energy dissipation structure to improve the energy dissipation effect of a sudden expansion and sloping stilling basin, including a submerged jet orifice 3, a diversion pier 2, and side piers 1. The submerged jet orifice 3 is opened on one end wall of the stilling basin 4, and is an integral structure with the end wall, penetrating along the thickness direction of the end wall to ensure that the water flow can be submerged into the stilling basin 4 horizontally. The diversion pier 2 and the two side piers 1 are all fixed to the bottom of the stilling basin 4, and are connected by being poured synchronously with the stilling basin 4 body to ensure structural stability and prevent displacement or damage caused by water flow impact. The two side piers 1 are symmetrically arranged on the two side walls of the stilling basin 4, and are tightly fitted and fixedly connected to the side walls. The diversion pier 2 is located at the transverse center of the stilling basin 4, and its central axis is precisely coincident with the central axis of the submerged jet orifice 3, so that the submerged water flow can be evenly diverted to the two sides by the diversion pier 2. The height of the heads of both the central pier 2 and the side pier 1 in the diversion channel is flush with the top of the submersible jet 3, ensuring that the water flow directly acts on the pier heads after exiting the jet and preventing water from overflowing from the pier top and weakening the diversion effect. The heads of the central pier 2 and the side pier 1 in the diversion channel are precisely positioned downstream of the submersible jet 3. L 1 = (1.5 ~ 2.0) d This location allows the ejected water flow to be intercepted by the pier before it can fully diffuse, providing a foundation for subsequent longitudinal stretching. The lengths of both the diversion pier 2 and the side pier 1 are set to... L = (2.0~3.0) H 1. Its top surface is a sloping surface that rises along the direction of water flow. The angle between the slope and the horizontal plane is controlled between 30° and 40°. The sloping structure guides the water flow upward along the slope, further enhancing the longitudinal stretching effect of the water flow, while reducing the impact force of the water flow on the pier. Two symmetrical spillways are formed between the two side piers 1 and the diversion pier 2. The contraction angle between the spillways and the side wall of the stilling basin 4 is... α The angle is 8°~12°. Based on the contraction angle α and the length L of the wide tail pier, the width of the tail of side pier 1 can be determined. b = L ×tan( α The width of the tail of the second pier in the diversion channel is 2. b This dimensional fit allows the drain channel to gradually contract. Drain channel outlet contraction ratio.ε = B 2 / B 1. Control the concentration between 0.4 and 0.5, where B 1 represents the width of the drain inlet. B 2 represents the width of the spillway outlet. The contraction structure causes the water flow to gradually converge within the spillway. After the water flows horizontally into the stilling basin 4 through the submerged jet orifice 3, it is first intercepted by the diversion pier 2, and evenly divided into two streams that enter the spillways on both sides respectively. Under the contraction of the spillway and the guidance of the pier's top slope, the two streams are continuously stretched longitudinally, the cross-section of the water flow gradually thins, the velocity distribution is readjusted, and strong longitudinal turbulence is generated. At the same time, the contracted water flows collide with each other at the spillway outlet, and combined with the sudden expansion effect within the stilling basin 4, a large number of eddies and water mixing phenomena are formed, converting the kinetic energy of the water flow into heat energy and potential energy, which is then dissipated.

[0023] This embodiment will be described in more detail with reference to one engineering example: The stilling basin 4 of a certain hydropower station has the following dimensions: the inlet of stilling basin 4 is a submerged circular hole with a diameter of 5.0m, the height of the sill is 4.0m, the elevation of the bottom plate of stilling basin 4 is 262.00m, the length of stilling basin 4 is 134.05m, the width of stilling basin 4 is 14.70m, the top elevation of the side wall is 291.00m, and the top elevation of the tail sill is 280.00m.

[0024] On the 1:35 hydraulic model of the above-mentioned project, a model test was conducted under the condition of a design flow rate of 820 m3 / s for stilling pool 4 (average flow velocity at the orifice is about 41 m / s). The effectiveness of this embodiment was verified by adding side pier 1 and diversion pier 2 and comparing the energy dissipation effect with that after stilling pool 4 was lengthened by 30m.

[0025] The newly added diversion pier 2 and two side piers 1 are initially positioned 7.5m downstream of the submerged jet orifice 3. The initial height of the diversion pier 2 and two side piers 1 is... H 1 is 9m; the lengths of the diversion pier 2 and the two side piers 1 are 9m. L The length is 18m; the top surface of the diversion pier 2 and the two side piers 1 is a sloping surface that rises along the flow path, and the angle between the sloping surface and the horizontal plane should be 31°. The center lines of the two jets formed in the chute are symmetrical to the center line of the stilling basin 4. The contraction angle α between the chute and the side wall should be 9°, and the contraction ratio ε at the outlet of the chute should be 0.50.

[0026] Hydraulic model tests were conducted to determine the water surface fluctuation characteristics, bottom velocity, and pulsating pressure of the stilling basin 4 in both the original design and this embodiment, and the energy dissipation rate was calculated. The test results of the embodiment show that adding this technical solution effectively reduces water surface fluctuation in the stilling basin 4, decreasing the maximum wave amplitude from 3.6m in the original design to 0.6m. The bottom velocity and pulsating pressure of the stilling basin 4 are also reduced to some extent. Based on the hydraulic characteristic indicators measured in the model tests, the energy dissipation rates of the original design and this invention were compared. The energy dissipation rate was calculated using the following formula:

[0027] In the above formula, E 0 represents the initial total energy of the water flowing into the stilling basin 4 section. E 1 represents the total energy at the tail sill after the energy dissipation in stilling pool 4.

[0028] Under the experimental conditions, the initial total energy of the water flowing into the stilling basin 4 is... E The elevation is 0 = 311.5m (expressed as head), and the calculation reference elevation is 280m. In the original design scheme, the total energy at the tail sill... E 1 consists of two parts: kinetic energy and potential energy. Kinetic energy E k =11.1 2 / (2 × 9.81) m, potential energy E k =(286.9-280)m, the energy dissipation rate k is calculated to be ((311.5-280)-(11.1)m. 2 / (2×9.81)+(286.9-280))) / (311.5-280)=(31.5-6.28-6.9) / 31.5=18.32 / 31.5x100% is 58%.

[0029] Total energy at the tail sill in this embodiment E 1. Kinetic energy E k =8.1 2 / (2 × 9.81) m, potential energy E k =(283-280)m, the energy dissipation rate k is calculated to be ((311.5-280)-(8.1)m. 2 / (2×9.81)+(283-280))) / (311.5-280)=(31.5-3.34-3) / 31.5=25.16 / 31.5x100%=80%. The energy dissipation rate is increased from 58% in the original scheme to 80%. Compared with the original design scheme, the energy dissipation rate of the present invention is significantly improved.

[0030] Model tests also show that if this technical solution is not added, the energy dissipation rate of stilling pool 4 must reach 80%, and its length must be extended by 30m, which is about 20%.

[0031] In other words, this embodiment can effectively improve the flood discharge and energy dissipation characteristics of the stilling basin 4, shorten the length of the stilling basin 4, and reduce the engineering construction cost.

[0032] Table 1. Comparison of hydraulic characteristics between the original stilling basin design and this embodiment.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin, characterized in that: One end wall of the slash-and-burn energy dissipation pool (4) is provided with a submerged jet orifice (3); the slash-and-burn energy dissipation pool (4) is provided with a diversion pier (2) and two side piers (1) along the water flow direction; the two side piers (1) are respectively set on the two side walls of the slash-and-burn energy dissipation pool (4), forming two symmetrical discharge channels with the diversion pier (2); the water flow passing through the submerged jet orifice (3) forms two longitudinally stretched water flows in the two discharge channels.

2. The auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion sill stilling basin according to claim 1, characterized in that: The central axis of the diversion pier (2) coincides with the central axis of the submerged jet orifice (3).

3. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin according to claim 1, characterized in that: The height of the pier head of the diversion pier (2) H 1 is flush with the top of the submerged injection port (3).

4. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin according to claim 1, characterized in that: The height of the two side piers (1) H 1 is flush with the top of the submerged injection port (3).

5. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion sill stilling basin according to claim 1, characterized in that: The heads of the diversion pier (2) and the side pier (1) are located downstream of the submerged jet opening (3). L 1 = (1.5 ~ 2.0) d Among them d The larger of the diameter of the submersible orifice (3) or the length and width of the rectangular outlet.

6. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin according to claim 3, characterized in that: The length of the diversion pier (2) L = (2.0~3.0) H 1.

7. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin according to claim 4, characterized in that: The length of the side pier (1) L = (2.0~3.0) H 1.

8. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin according to claim 1, characterized in that: The top surfaces of the diversion pier (2) and the side pier (1) are sloping surfaces that rise along the flow path, and the angle between the sloping surface and the horizontal plane is 30°~40°.

9. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin according to claim 1, characterized in that: The angle of contraction between the trough and the side wall of the stilling basin (4) α The angle is 8°~12°, and the width of the tail of the side pier (1) is... b = L ×tan( α The width of the tail of the diversion pier (2) is 2. b .

10. An auxiliary energy dissipation device for improving the energy dissipation effect of a sudden expansion and drop sill stilling basin according to claim 1, characterized in that: The outlet shrinkage ratio of the discharge channel ε = B 2 / B 1 is 0.4~0.5, of which B 1 represents the width of the drain inlet. B 2 represents the width of the discharge channel outlet.

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