Energy dissipation and flow stabilization device for stilling pool under low Froude number condition

Abstract

The utility model relates to the technical field of water conservancy projects, in particular to a stilling pool energy dissipation and flow stabilization device under the low Froude number condition. The upstream face of the initial end of the stilling pool body is in a parabola shape, water flow guiding and impact reducing are facilitated, the downstream face inclines backwards and is provided with a vertical groove, water flow can be promoted to form a backflow area to consume energy, the side face is in a gradually-changing shrinkage mode, a small guide plate is further arranged close to the bottom, the flow state can be stabilized, and water body mixing energy dissipation can be enhanced; the stilling pool body is rectangular, a tail ridge is arranged at the tail end of the stilling pool body, and a V-shaped pier is further arranged in the stilling pool body. By optimizing the structural design of the stilling pool, the energy dissipation efficiency and the water flow stability under the low Froude number condition are improved, the problem that a traditional stilling pool is poor in energy dissipation effect under the low Froude number condition is solved, the scouring risk to a downstream riverbed and a bank slope is effectively reduced, and the energy dissipation effect of the stilling pool is improved. And safe and stable operation of the water conservancy project is guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of water conservancy engineering technology, specifically to a stilling basin energy dissipation and flow stabilization device under low Froude number conditions. Background Technology

[0002] In the field of hydraulic engineering, stilling basins serve as important energy dissipation facilities. Their function is to eliminate the energy of downstream water flow through hydraulic jumps and other methods, ensuring the stability of downstream water flow and preventing erosion damage to the downstream riverbed and banks. However, under low Froude number conditions, the energy dissipation and flow stabilization effect of stilling basins often faces many challenges. The Froude number (Fr) is an important parameter characterizing the relative magnitude of the inertial force of water flow and gravity. When the Froude number is low, the inertial force of water flow is relatively weak, and the effect of gravity is more prominent, making it difficult for hydraulic jumps to fully form and significantly reducing the energy dissipation effect. In practical engineering, such as sluice gates and small hydropower stations in plain areas, the water flow is usually in a low Froude number state due to the small difference in water level between upstream and downstream. In this case, traditional stilling basin designs often cannot effectively eliminate water flow energy, leading to instability in downstream water flow.

[0003] Existing stilling basin energy dissipation technologies have many limitations under low Froude number conditions. For example, some stilling basins employ simple bottom flow energy dissipation methods, relying solely on the roughness and geometry of the basin bottom to promote hydraulic jump formation. However, at low Froude numbers, this method struggles to generate sufficient resistance to drive the hydraulic jump, resulting in low energy dissipation efficiency. Furthermore, some stilling basins are equipped with auxiliary energy dissipation facilities such as stilling blocks. While these can increase flow turbulence to some extent, their effectiveness is limited due to the low flow velocity and limited energy at low Froude numbers. In fact, they may even lead to more turbulent flow patterns, increasing adverse impacts on downstream channels. Utility Model Content

[0004] The purpose of this invention is to provide an energy dissipation and flow stabilization device for stilling basins under low Froude number conditions, so as to solve the problems of low energy dissipation efficiency, turbulent water flow, and poor adaptability of existing stilling basins under low Froude number conditions.

[0005] To achieve the above objectives, a stilling basin energy dissipation and flow stabilization device is provided under low Froude number conditions, comprising a stilling basin body, wherein the beginning of the stilling basin body is provided with a water-facing surface, a water-returning surface, and a side surface, wherein:

[0006] The water-facing surface adopts a parabolic design;

[0007] The backwater surface adopts a backward tilting design with a backward tilting angle between 15° and 30°. Vertical grooves are provided on the backwater surface, with a groove depth of 5-10cm, a width of 8-15cm, and a spacing of 20-30cm.

[0008] The side surface adopts a gradual contraction form, gradually contracting from the water-facing side to the back side, with the contraction ratio controlled between 1:1.2 and 1:1.5.

[0009] As a further improvement to this technical solution, a small guide plate is provided on the side near the bottom. The guide plate is 30-50cm long and has an angle of 30°-45° with the side.

[0010] As a further improvement to this technical solution, the junctions of the water-facing side, the back side, and the side surface are chamfered.

[0011] As a further improvement to this technical solution, the stilling pool has a rectangular structure with a length of 15-30 meters, a width of 8-15 meters, and a depth of 3-5 meters. The inner wall and bottom surface of the stilling pool are smooth planar shapes.

[0012] As a further improvement to this technical solution, the end of the stilling pool is provided with a tail sill, which is 1-1.5 meters high, 1.2-1.8 meters wide, and has an arc-shaped top.

[0013] As a further improvement to this technical solution, the stilling pool is equipped with V-shaped piers, which adopt a V-shaped structure design with an angle of 90°.

[0014] As a further improvement to this technical solution, a pressure sensor is installed on the side wall of the stilling pool, a flow meter is installed at the inlet and outlet of the stilling pool, and a displacement meter is installed on the pool wall and bottom of the stilling pool.

[0015] As a further improvement to this technical solution, the stilling pool is located in the energy dissipation section, the front of the energy dissipation section is connected to the diffusion section, the rear of the energy dissipation section is connected to the apron section, and the front of the diffusion section is connected to the water diversion channel.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] 1. In this stilling basin energy dissipation and flow stabilization device under low Froude number conditions, the upstream face adopts a parabolic design, which allows the water flow to adhere smoothly and be diverted along the pier, reducing the direct impact of the water flow on the pier, lowering the degree of water flow turbulence, and improving the energy dissipation effect. The downstream face's backward-sloping design promotes the formation of a relatively stable backflow zone, further consuming water flow energy through the interaction between the backflow and the main flow. At the same time, the vertical grooves on the downstream face disturb the water flow boundary layer, increasing turbulence and enhancing energy dissipation. The gradually tapering design on the sides ensures a smooth water flow transition, and the small guide plate at the bottom guides the water flow downward, enhancing bottom water flow turbulence and promoting overall water mixing and energy dissipation. Overall, this design makes the water flow energy dissipate more efficiently, and compared with traditional stilling basins, it can more effectively eliminate the energy of the downstream water flow under low Froude number conditions.

[0018] 2. In this stilling basin energy dissipation and flow stabilization device under low Froude number conditions, the gradually tapering side design avoids water flow separation and vortices, stabilizing the flow pattern. Small guide vanes guide the water flow direction, reducing lateral and longitudinal fluctuations. Furthermore, a tail sill located at the end of the stilling basin, with an arc-shaped top, further adjusts the velocity distribution of the outflow, reduces the bottom velocity, stabilizes the hydraulic jump within the stilling basin, and ensures a more uniform and stable downstream flow velocity and volume, preventing scouring and erosion of the downstream river channel by unfavorable flow patterns. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0020] Figure 2 This is a top view of the structure of this utility model;

[0021] Figure 3 This is a schematic diagram of the structure of the stilling pool of this utility model.

[0022] Figure 4 This is a schematic diagram of the structure of the V-shaped pier of this utility model.

[0023] The meanings of the labels in the diagram are as follows:

[0024] 1. Water diversion channel; 2. Diffusion section; 3. Energy dissipation section; 31. Stilling basin body; 32. Water-facing side; 33. Water-repelling side; 331. Groove; 34. Side; 35. V-shaped pier; 36. Tail sill; 4. Protective apron section. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] In the description of this utility model, 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", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] Please see Figures 1-4 As shown, the purpose of this embodiment is to provide an energy dissipation and flow stabilization device for a stilling basin under low Froude number conditions, including a stilling basin body 31. The stilling basin body 31 is located in the energy dissipation section 3, which is the core part of the system. The energy dissipation section 3 is connected to the diffuser section 2 in front and to the apron section 4 in rear. The diffuser section 2 is connected to the water diversion channel 1 in front.

[0029] The water diversion channel 1 is located at the very front of the entire system. Its cross-section is trapezoidal, and its bottom is lined with anti-erosion material. By controlling the direction and velocity of the water flow, it reduces sediment transport and prevents siltation in the initial section. The end of the water diversion channel 1 connects to the diffuser section 2 to ensure a uniform transition of water flow to the diffuser section 2.

[0030] Diffusion section 2 connects water diversion channel 1 and energy dissipation section 3, and adopts a gradually expanding design, with its width gradually increasing from 5 meters in water diversion channel 1 to 12 meters in energy dissipation section 3. Its core function is to reduce water flow velocity, evenly distribute the flow rate, and avoid concentrated impact of water flow on the inlet of energy dissipation section 3. The bottom of diffusion section 2 is equipped with a gentle slope (slope 1:15), which disperses water flow energy through the gradually increasing cross-sectional area, creating stable inlet conditions for the efficient energy dissipation of the subsequent energy dissipation section 3.

[0031] Abutment section 4 is located behind energy dissipation section 3 and directly connects to the downstream channel. It is 10 meters long, constructed of reinforced concrete, and covered with an erosion-resistant and abrasion-resistant layer. The function of abutment section 4 is to further smooth the water flow and even out the velocity distribution. A flexible protective structure (such as riprap or gabion mesh) at its end absorbs residual energy, preventing localized erosion of the downstream riverbed and banks by the dissipated water flow. Abutment section 4 and energy dissipation section 3 are smoothly connected to avoid secondary turbulence in the water flow.

[0032] The stilling pool 31 in the energy dissipation section 3 has a rectangular structure, with a length of 20 meters, a width of 12 meters, and a depth of 4 meters. It is made of C35 reinforced concrete, and the inner wall and bottom surface are polished to form a smooth surface to reduce water flow resistance.

[0033] The upstream face 32 is located at the beginning of the stilling basin 31 and adopts a parabolic design. Its parabolic equation was determined through hydraulic model tests and numerical simulation optimization. For example, when the water flow velocity is 2.5 m / s and the flow rate is 50 m³ / s, the parabolic equation is [equation missing]. This design guides the water flow to adhere smoothly to the basin surface, reducing direct impact on the upstream face 32 and lowering turbulent energy loss by approximately 25%. The downstream face 33 is located downstream of the upstream face 32, with a backward inclination angle of 20°. Vertical grooves 331 are evenly distributed on its surface, with a depth of 8 cm, a width of 12 cm, and a spacing of 25 cm. The grooves 331 disrupt the water boundary layer, causing a stable backflow zone to form behind the downstream face 33. The interaction between the backflow and the main flow can additionally consume 15%-20% of the water flow energy.

[0034] The side surface 34 gradually narrows from the water-facing side 32 to the water-repelling side 33, with a narrowing ratio of 1:1.3, ensuring a smooth water flow transition and preventing separation and vortex generation. Near the bottom of the side surface 34, three sets of guide vanes are installed at equal intervals along the water flow direction. Each guide vane is 40cm long, forms a 35° angle with the side surface 34, and its end is 8cm from the bottom of the pool. The guide vanes guide the water flow downwards, enhancing bottom turbulence and promoting mixing between the upper and lower water layers, thus improving energy dissipation efficiency by approximately 18%. A V-shaped pier 35 is installed in the middle of the stilling basin 31. The V-shaped opening angle is 90°, with the tip pointing upstream, and its height is flush with the bottom of the pool. The V-shaped piers 35 are arranged at 5-meter intervals along the length of the pool, with two piers in each row. Through flow diversion, they increase water flow collision and turbulence, further enhancing the energy dissipation effect.

[0035] Tail sill 36 is located at the end of stilling basin 31, with a height of 1.2 meters and a width of 1.5 meters. Its top is arc-shaped, with the radius of curvature matching the energy dissipation and flow stabilization device. Tail sill 36 reduces the bottom flow velocity from 1.8 m / s to 1.2 m / s by adjusting the velocity distribution of the outflow, stabilizing the hydraulic jump and preventing downstream riverbed scouring. Pressure sensors are installed on the sidewalls of the stilling basin to monitor structural stress in real time; flow meters are installed at the inlet and outlet to collect water flow velocity data; displacement gauges are installed on the basin walls and bottom to monitor structural deformation and ensure operational safety.

[0036] In this embodiment, the device achieves an energy dissipation efficiency of 78%-85% under low Froude number (Fr=1.2-1.8) conditions through the parabolic guidance of the water-facing surface 32, the turbulence of the groove 331 on the back water-facing surface 33, the contraction and diversion of the side surface 34, and the diversion effect of the V-shaped pier 35. This is 30%-40% higher than that of traditional stilling basins. The downstream water flow velocity distribution is uniform, and the lateral fluctuation is reduced by 60%, effectively preventing bank collapse and riverbed erosion.

[0037] To verify the design effectiveness, a 1:20 scale hydraulic model was used for testing. The test showed that under low Froude number conditions, the turbulence intensity inside the device increased by 50%, and the energy dissipation rate significantly improved. Simultaneously, CFD numerical simulations showed that the water flow formed symmetrical vortices after passing through the V-shaped pier 35, increasing the energy conversion efficiency by 22%. In practical engineering applications, the device has been successfully used in the renovation of a plain sluice gate. After one year of operation, monitoring data showed that the downstream riverbed scour depth decreased by 70%, verifying its long-term stability.

[0038] Working principle: Water is smoothly introduced from the diversion channel 1, gradually widens in the diffusion section 2, reduces the flow velocity, and is evenly distributed to the energy dissipation section 3. The stilling basin 31 within the energy dissipation section 3 guides the water flow through the parabolic design of the water-facing surface 32, reducing direct impact and allowing the water to smoothly enter the basin along the curved surface. The backwater surface 33 adopts a 20° backward tilt angle, and vertical grooves 331 on its surface disrupt the water flow boundary layer, forming a stable backflow zone. Energy is dissipated through the interaction between the backflow and the main flow. The side surface 34 adopts a 1:1.3 contraction ratio gradual structure to avoid water flow separation. A guide plate installed at the bottom guides the water flow downward at a 35° angle, enhancing bottom turbulence and promoting vertical energy mixing.

[0039] In the middle of energy dissipation section 3, a V-shaped pier 35 is arranged, with its 90° opening facing upstream, splitting the water flow into two streams. This forces the split water to collide behind the pier, generating a strong vortex, further dissipating energy through momentum exchange. The tail sill 36 is located at the end of the pool, its arc-shaped top adjusting the outflow and reducing the bottom velocity to 1.2 m / s, stabilizing the hydraulic jump. The water then enters the apron section 4, where its erosion-resistant layer and flexible end protection structure absorb residual energy, ensuring uniform downstream velocity distribution and preventing localized scouring.

[0040] Pressure sensors monitor the stress on the sidewalls of the stilling basin (31) in real time, flow meters collect flow velocity data at the inlet and outlet, and displacement gauges track the deformation of the basin walls and bottom, forming a dynamic feedback system that supports adaptive adjustments to the angle of the guide vanes or the layout of the V-shaped piers (35). Through the synergistic effect of the entire process of "guidance-turbulence-collision-stabilization," this device gradually converts gravitational potential energy into turbulent kinetic energy and thermal energy under low Froude number conditions, achieving an energy dissipation efficiency of 78%-85% and reducing the downstream riverbed scour depth by 70%, thus achieving efficient energy dissipation and long-term protection.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A stilling basin energy dissipation and flow stabilization device under low Froude number conditions, characterized in that: The stilling basin includes a stilling basin body (31), the stilling basin body (31) having a water-facing surface (32), a water-returning surface (33), and a side surface (34) at its starting end, wherein: The water-facing surface (32) adopts a parabolic design; The backwater surface (33) adopts a backward tilting design with a backward tilting angle between 15° and 30°, and a vertical groove (331) is provided on the backwater surface (33). The side (34) adopts a gradually contracting form, gradually contracting from the water-facing side (32) to the water-repelling side (33).

2. The stilling basin energy dissipation and flow stabilization device under low Froude number conditions according to claim 1, characterized in that: A small guide plate is provided near the bottom of the side (34). The guide plate is 30-50cm long and has an angle of 30°-45° with the side (34).

3. The stilling basin energy dissipation and flow stabilization device under low Froude number conditions according to claim 1, characterized in that: The water-facing surface (32), the back surface (33), and the side surface (34) are chamfered at their junctions.

4. The stilling basin energy dissipation and flow stabilization device under low Froude number conditions according to claim 1, characterized in that: The stilling pool body (31) has a rectangular structure with a length of 15-30 meters, a width of 8-15 meters, and a depth of 3-5 meters. The inner wall and bottom surface of the stilling pool body (31) are smooth planar shapes.

5. The stilling basin energy dissipation and flow stabilization device under low Froude number conditions according to claim 4, characterized in that: The end of the stilling pool (31) is provided with a tail sill (36), which is 1-1.5 meters high, 1.2-1.8 meters wide, and has an arc-shaped top.

6. The stilling basin energy dissipation and flow stabilization device under low Froude number conditions according to claim 4, characterized in that: The stilling pool body (31) is equipped with a V-shaped pier (35), which adopts a V-shaped structure design with an angle of 90°.

7. The stilling basin energy dissipation and flow stabilization device under low Froude number conditions according to claim 1, characterized in that: Pressure sensors are installed on the side walls of the stilling pool (31), flow meters are installed at the inlet and outlet of the stilling pool (31), and displacement meters are installed on the pool walls and bottom of the stilling pool (31).

8. The stilling basin energy dissipation and flow stabilization device under low Froude number conditions according to claim 1, characterized in that: The stilling pool (31) is located in the energy dissipation section (3). The energy dissipation section (3) is connected to the diffusion section (2) in front and to the protective section (4) behind. The diffusion section (2) is connected to the water diversion channel (1) in front.

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