A method of arranging V-shaped hollow sills for lateral water diversion pools

Abstract

The application discloses a V-shaped hollow sill arrangement method for a lateral water distribution pool, and comprises the following steps: determining an inlet flow water level and a flow velocity, and calculating an inlet Froude number Fr; through numerical simulation of multiple flow conditions, an outlet comprehensive uniformity is calculated according to a lateral water distribution outlet section of the water distribution pool; data scatter point curves are fitted to obtain a unimodal function curve of the lateral outflow uniformity changing with the lateral sill angle under each flow condition, and a curve peak value is recorded; an exponential growth curve function of the lateral outflow uniformity peak value changing with the Froude number under each flow condition is obtained; and based on the determined Froude number, a diffusion angle of the lateral water distribution side of the sill is obtained and adjusted. According to the application, the V-shaped sill with a variable angle is set according to different flow conditions, so that the V-shaped sill is suitable for various flow conditions, and the engineering cost is reduced, and the hub benefit of the water distribution gate station is improved.

Description

Technical Field

[0001] This invention belongs to the field of flow pattern improvement in water conservancy projects, and specifically relates to a method for arranging a V-shaped hollow bottom sill for a lateral water distribution tank. Background Technology

[0002] The sluice gate hub is a key engineering project integrating a sluice gate and a pumping station, capable of meeting water intake demands from multiple directions. The diversion pool is the core intake structure of the sluice gate hub, connecting the upstream tunnel and the downstream sluice gate intake structures. Under lateral intake conditions, the influence of the bend generates centrifugal force, causing changes in flow velocity and pressure on the inner and outer sides. Furthermore, due to inertia, the fluid tends to flow towards the outer sidewall, further exacerbating the "wall detachment" phenomenon. This results in a significant reduction in the cross-sectional area of ​​the forebay, uneven streamline distribution, and the formation of vortices, backflow, and other undesirable flow patterns, directly impacting the safe and efficient operation of the pumping station.

[0003] To mitigate the impact of undesirable flow patterns in diversion basins, scholars both domestically and internationally have conducted extensive research on flow pattern improvement. In practical engineering applications, sills, as a flow pattern improvement measure, can adjust the cross-sectional flow structure to improve the flow pattern, resulting in a more uniform velocity distribution across the transverse and longitudinal sections. However, the traditional arrangement of sills, due to their shape parameters being related to flow rate and water level, generally results in limited flow pattern improvement under various lateral inflow conditions. Summary of the Invention

[0004] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention discloses a method for arranging a V-shaped hollow bottom sill for a lateral diversion pool. This method sets a variable angle V-shaped bottom sill according to different inflow conditions, making it applicable to various inflow conditions. It is of great significance for reducing engineering costs, improving the benefits of diversion gate hubs, and providing a reference for the arrangement of bottom sills in diversion pools.

[0005] Technical solution: The present invention discloses a method for arranging a V-shaped hollow bottom sill for a lateral water distribution tank, comprising the following steps:

[0006] S1. Determine the inlet water level and velocity, calculate the inlet Froude number Fr, and use the Froude number Fr to represent the inlet flow situation;

[0007] S2. By numerically simulating multiple inflow scenarios, the overall uniformity of the outlet is calculated based on the lateral diversion outlet cross-section of the water distribution pool, and data scatter points are obtained.

[0008] S3. Fit the data scatter curve to obtain a single-peak function curve showing the change of lateral outflow uniformity with the angle between the bottom sill branch side and the centerline under various inflow conditions, and record the peak value of the curve.

[0009] S4. Correlate the peak value of the curve with the Froude number Fr under the incoming flow conditions to obtain the exponential growth curve function of the peak value of the lateral outflow uniformity as a function of the Froude number under each incoming flow condition.

[0010] S5. Based on the exponential growth curve function in S4, obtain and adjust the angle between the diversion side of the bottom sill and the center line of the diversion pool based on the determined Froude number.

[0011] Furthermore, S2 simulates the flow patterns of the water distribution pool under multiple incoming flow conditions, where the angle of the bottom sill on the diversion side changes.

[0012] Furthermore, the formula for calculating uniformity in S2 is as follows:

[0013]

[0014] in, u ai The velocity of the water flow along the main flow direction at any measuring point on the cross-section of the outlet of the lateral diversion section of the water distribution pool.

[0015] u ave The average velocity of the water flow along the main flow direction at any measuring point on the cross-section of the outlet of the lateral diversion section of the water distribution pool.

[0016] n The number of measurement points.

[0017] Furthermore, the curve function in S4 is as follows:

[0018]

[0019] θ1 is the angle between the diversion side of the bottom sill and the center line.

[0020] Furthermore, the water distribution pool includes an upstream culvert section, a diffusion section, a leveling end, a lateral diversion section, and a forward diversion section through which the water flows in sequence; the diffusion section is provided with a first adjustable V-shaped hollow bottom sill and a second adjustable V-shaped hollow bottom sill for rectification.

[0021] Furthermore, the rotation points of the first adjustable V-shaped hollow bottom sill and the second adjustable V-shaped hollow bottom sill are both arranged on the center line of the water distribution pool. The hollow bottom sill structures on both sides of the rotation point are consistent. The first adjustable V-shaped hollow bottom sill has two holes on one side, and the second adjustable V-shaped hollow bottom sill has three holes on one side.

[0022] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0023] The V-shaped apex angle can be adjusted according to different flow rates and water levels to achieve better flow pattern improvement. When there is no lateral flow diversion in the water distribution tank, the bottom sills on both sides of the variable V-shaped perforation are set to 0°. In this case, the bottom sills can not only effectively distribute the cross-sectional velocity, but also distribute the central water flow to both sides, thus improving the outlet uniformity. When there is lateral flow diversion on both sides of the water distribution tank, it is necessary to adjust the bottom sill angle on the side with flow diversion according to the relationship curve between the bottom sill angle and the inlet Froude number to make the bottom sill rectification effect better.

[0024] The V-shaped bottom sill is set inside the diffusion section of the water distribution tank, with its apex aligned with the axis of the water distribution tank. This reduces the impact of backflow within the diffusion section, resulting in a more uniform water flow velocity distribution inside the water distribution tank and enabling the water pump unit to operate more stably.

[0025] A suitable sill width ensures structural strength while reducing manufacturing costs. A suitable sill height enhances its flow-carrying effect and ensures sufficient flow area, minimizing hydraulic losses.

[0026] The openwork bottom sill structure reduces the vertical turbulence of water flow behind the sill, further optimizing the inflow conditions. Ensuring sufficient open space in the sill allows for a greater proportion of straight water flow, effectively improving the flow pattern of water cascading down the sill. Attached Figure Description

[0027] Figure 1 This is a top view of the water distribution tank of the present invention;

[0028] Figure 2 This is a structural diagram of the first adjustable V-shaped hollow bottom sill of the present invention;

[0029] Figure 3 This is a diagram of the second adjustable V-shaped hollow bottom sill structure of the present invention;

[0030] Figure 4 The curves show the overall uniformity of the lateral diversion section under different inflow conditions as a function of the angle of one side of the adjustable V-shaped bottom sill;

[0031] Figure 5 The curve showing the change of the angle on one side of the optimal adjustable V-shaped sill as a function of the Froude number. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0033] like Figure 1-3As shown, the water distribution tank includes an upstream culvert section 1, a diffuser section 2, a leveling end 3, a lateral diversion section 4, and a forward diversion section 5 through which water flows in sequence. The diffuser section 2 is equipped with a first adjustable V-shaped perforated sill 6 and a second adjustable V-shaped perforated sill 7 for rectifying the flow. The rotation points of the first adjustable V-shaped perforated sill 6 and the second adjustable V-shaped perforated sill 7 are both arranged on the center line of the water distribution tank. The perforated sill structures on both sides of the rotation point are identical. The first adjustable V-shaped perforated sill 6 has two holes on one side, and the second adjustable V-shaped perforated sill 7 has three holes on one side.

[0034] The length L of the diffusion section 2 of the water distribution pool is 50m, the starting width B of the diffusion section is 5m, the diffusion angle θ is 22.62°, and the slope i is 0.412%.

[0035] The first adjustable V-shaped hollow sill 6 has its rotation point located on the center line 8 of the water distribution pool. The distance from the rotation point to the starting point of the diffusion section is L1 = 0.3L = 15m. The V-shaped hollow sills on both sides of the rotation point have the same structure, with two holes on each side. The sill length is L2 = 5.3m, the sill width is B1 = 0.8m, and the sill height is H1 = 1m.

[0036] The center of the first hole on one side of the rotating point's V-shaped hollow sill has a distance of L3 = 1 / 3L2 = 1.62m from the outer side, a hole width of B2 = 0.18B = 0.9m, and a hole height of H2 = 0.6H1 = 0.6m. The center of the second hole on one side of the rotating point's V-shaped hollow sill has a distance of L4 = 1 / 3L2 = 1.62m from the inner side, a hole width of B3 = 0.18B = 0.9m, and a hole height of H3 = 0.6H1 = 0.6m.

[0037] The second adjustable V-shaped hollow sill 7 has its rotation point located on the center line 8 of the water distribution pool. The distance from the rotation point to the starting point of the diffusion section is L5 = 0.7L = 35m. The V-shaped hollow sills on both sides of the rotation point have the same structure, with 3 holes on each side. The sill length is L6 = 9.2m, the sill width is B4 = 0.8m, and the sill height is H4 = 1m.

[0038] The center of the first hole on one side of the rotating point's V-shaped hollow sill has a distance of L7 = 2 / 9L6 = 2m from the outer side, a hole width of B5 = 0.24B = 1.2m, and a hole height of H5 = 0.6H4 = 0.6m. The center of the second hole on one side of the rotating point's V-shaped hollow sill has a distance of L8 = 1 / 2L6 = 4.6m from the outer side, a hole width of B6 = 0.24B = 1.2m, and a hole height of H6 = 0.6H4 = 0.6m. The center of the third hole on one side of the rotating point's V-shaped hollow sill has a distance of L9 = 2 / 9L6 = 2m from the inner side, a hole width of B7 = 0.24B = 1.2m, and a hole height of H7 = 0.6H4 = 0.6m.

[0039] When setting up the bottom sill, the angle between it and the centerline is determined in the following way, including the following steps:

[0040] S1. Determine the inlet water level and velocity, calculate the inlet Froude number Fr, and use the Froude number Fr to represent the inlet flow situation;

[0041] S2. By numerically simulating the flow pattern of the water distribution pool under multiple incoming flow conditions with varying angles of the bottom sill on the diversion side, the overall uniformity of the outlet is calculated based on the lateral diversion outlet cross-section of the water distribution pool, and data scatter points are obtained.

[0042] The formula for calculating uniformity is as follows:

[0043]

[0044] in, u ai The velocity of the water flow along the main flow direction at any measuring point on the cross-section of the outlet of the lateral diversion section of the water distribution pool.

[0045] u ave The average velocity of the water flow along the main flow direction at any measuring point on the cross-section of the outlet of the lateral diversion section of the water distribution pool.

[0046] n The number of measurement points.

[0047] S3. Fit the scatter plot curve to obtain a single-peak function curve showing the variation of lateral outflow uniformity with the angle between the bottom sill branch side and the centerline under various inflow conditions. Record the peak value of the curve, such as... Figure 4 As shown;

[0048] S4. Correlate the peak value of the curve with the Froude number Fr for the incoming flow conditions to obtain an exponential growth curve function of the peak value of the lateral outflow uniformity as a function of the Froude number for each incoming flow condition, such as... Figure 5 As shown;

[0049] The curve function is as follows:

[0050]

[0051] θ1 is the angle between the left side of the bottom sill and the center line of the water distribution pool.

[0052] S5. Based on the exponential growth curve function in S4, obtain the angle between the left side of the bottom sill and the center line of the water distribution pool based on the determined Froude number, and make physical adjustments.

[0053] In this embodiment, the inlet boundary flow rate is 23.5 m³ / s. 3 / s, the water level upstream of the sluice gate is 530.52m, the β-direction diversion gate and the α-direction four-gate diversion gate are open, the flow rate of the β-direction diversion gate is 14.5m³ / s. 3 / s.

[0054] Under this condition, the Froude number is 0.317. According to the curve of the Froude number at the diffuser inlet and the optimal variation angle of the left side sill, the overall uniformity of the lateral diversion section is the best when the angle of the left side sill is adjusted to 8.01°.

[0055] By using the central rotating device of the adjustable V-shaped hollow bottom sill, the right bottom sill is kept fixed, while the angle of the left bottom sill is adjusted to 8.01°.

Claims

1. A method for arranging a V-shaped perforated bottom sill for a lateral water distribution tank, characterized in that, Includes the following steps: S1. Determine the inlet water level and velocity, calculate the inlet Froude number Fr, and use the Froude number Fr to represent the inlet flow situation; S2. By numerically simulating multiple inflow scenarios, the overall uniformity of the outlet is calculated based on the lateral diversion outlet cross-section of the water distribution pool, and data scatter points are obtained. S3. Fit the data scatter curve to obtain a single-peak function curve showing the change of lateral outflow uniformity with the angle between the bottom sill branch side and the centerline under various inflow conditions, and record the peak value of the curve. S4. Correlate the peak value of the curve with the Froude number Fr under the incoming flow conditions to obtain the exponential growth curve function of the peak value of the lateral outflow uniformity as a function of the Froude number under each incoming flow condition. S5. Based on the exponential growth curve function in S4, obtain and adjust the angle between the diversion side of the bottom sill and the center line of the diversion pool based on the determined Froude number. The water distribution pool includes an upstream culvert section (1), a diffusion section (2), a leveling end (3), a lateral diversion section (4), and a forward diversion section (5) through which the water flows in sequence; the diffusion section (2) is provided with a first adjustable V-shaped hollow bottom sill (6) and a second adjustable V-shaped hollow bottom sill (7) for rectifying the flow. The rotation points of the first adjustable V-shaped hollow bottom sill (6) and the second adjustable V-shaped hollow bottom sill (7) are both arranged on the center line of the water distribution pool. The hollow bottom sill structures on both sides of the rotation point are the same. The first adjustable V-shaped hollow bottom sill (6) has two holes on one side, and the second adjustable V-shaped hollow bottom sill (7) has three holes on one side.

2. The method for arranging a V-shaped hollow bottom sill for a lateral water distribution tank according to claim 1, characterized in that: S2 simulates the flow patterns of the water distribution pool under multiple incoming flow conditions, where the angle of the bottom sill on the diversion side changes.

3. The method for arranging a V-shaped perforated bottom sill for a lateral water distribution tank according to claim 1, characterized in that, The formula for calculating uniformity in S2 is as follows: ， in, u ai The velocity of the water flow along the main flow direction at any measuring point on the cross-section of the outlet of the lateral diversion section of the water distribution pool. u ave The average velocity of the water flow along the main flow direction at any measuring point on the cross-section of the outlet of the lateral diversion section of the water distribution pool. n The number of measurement points.

4. The method for arranging a V-shaped perforated bottom sill for a lateral water distribution tank according to claim 1, characterized in that, The curve function in S4 is as follows: ， θ1 is the angle between the bottom sill branch side and the centerline.

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