Operation method of rotary opening and closing type trapezoidal gate for controlling flow

Abstract

The invention relates to an operation method of a rotary opening and closing type trapezoidal gate for controlling flow, which comprises the following steps of: firstly, applying a dimensional analysis method to physical parameters influencing flow Q to obtain a first relational expression between the flow Q and a rotation angle theta; according to an existing gate system, a test system which is scaled down in equal proportion is built, and test data of the physical parameters involved in the first relational expression are obtained; inputting the test data into a gate control system, and deriving a second relational expression between the flow Q and the rotation angle theta through a preset numerical fitting method in combination with the first relational expression and the test data; and finally, the flow required by actual operation and the measured physical parameters of the existing gate are input into the gate control system, and the gate control system controls the gate to open the rotation angle theta according to the second relational expression. The opening and closing mode and the shape characteristic of the rotary opening and closing type trapezoidal gate are fully considered, the flow of the rotary opening and closing type trapezoidal gate can be accurately controlled, and technical guarantee is provided for accurate irrigation.

Description

Technical Field

[0001] The invention relates to a gate operation method, in particular to an operation method of a rotary opening and closing trapezoidal gate for controlling flow. Background Art

[0002] In the irrigation system, the trapezoidal gates set in the trapezoidal channels have the advantage of low construction difficulty because they do not require the construction of the gate chamber and the ancillary buildings connected to the gate chamber. In addition, for some old irrigation systems, the corresponding trapezoidal gates can be selected according to the size of the original channels, without the need for large-scale reconstruction of the channels, and the engineering cost is relatively low.

[0003] Controlling the flow of water at different flow rates through the gate can meet the water requirements of different crops at different growth stages, and has a good application prospect, but how to accurately control the flow of the rotary opening and closing trapezoidal gate is still a difficult point. Researchers have conducted a lot of research on how to calculate the flow of rectangular gates and arc gates, and the corresponding flow formulas have been relatively complete. For uncommon trapezoidal gates, the inventor's research group has also conducted a number of studies, such as the Chinese invention with publication number CN114626316A, which discloses a method for calculating the flow of free outflow of vertical opening and closing trapezoidal flat gates.

[0004] However, compared with the vertical lifting of the vertical opening and closing trapezoidal gate, the flow boundary conditions of the rotary opening and closing trapezoidal gate change. The gate leaf of the rotary opening and closing trapezoidal gate is obliquely crossed with the water flow, avoiding the direct collision between the water flow and the gate, thereby reducing the energy loss caused by collision and friction, and the conversion amount of water flow energy changes. In addition, due to the difference in opening and closing methods, the calculation formula of the water flow cross-sectional area under the rotary opening and closing method is completely different from that of the vertical opening and closing trapezoidal gate. Therefore, the calculation method of the vertical opening and closing trapezoidal gate cannot be simply applied to the rotary opening and closing trapezoidal gate. Different flow calculation methods are required to accurately calculate the flow through the gate and control the water flow.

[0005] Therefore, the problem of how to control the opening and closing of the rotary open-close trapezoidal gate to obtain accurate outflow flow needs to be solved urgently. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an operating method for a rotary opening and closing trapezoidal gate which can accurately calculate the outflow flow of the rotary opening and closing trapezoidal gate and precisely control the flow.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: an operation method of a rotary opening and closing trapezoidal gate for controlling flow,

[0008] Applying the dimensional analysis method to the physical parameters that affect the flow rate Q, the first relationship between the flow rate Q and the rotation angle θ is obtained;

[0009] Building a proportionally reduced test system based on the existing gate system to obtain test data of the physical parameters involved in the first relational expression;

[0010] The test data is input into the gate control system, and a second relationship between the flow rate Q and the rotation angle θ is derived by combining the first relationship and the test data through a preset numerical fitting method;

[0011] The flow required for actual operation and the measured physical parameters of the existing gate are input into the gate control system, and the gate control system controls the gate to open the rotation angle θ according to the second relationship.

[0012] Specifically, the physical parameters affecting the flow rate Q are as follows:

[0013] The effective parameters in the free outflow phenomenon are: channel slope coefficient m, rotation angle θ, water head H before the gate 0 , flow width B, gravitational acceleration g, dynamic viscosity coefficient ν and water density ρ, rotating trapezoidal gate length L 1 , Height from gate rotation axis to channel bottom plate L 2 , the functional relationship is formula (1)

[0014] f F (Q F ,m,θ,H 0 ,B,g,v,ρ,L1,L2)=0 (1)

[0015] The effective parameters in the flooded outflow phenomenon are: channel slope coefficient m, rotation angle θ, water head H before the gate 0 , flow width B, gravitational acceleration g, dynamic viscosity coefficient ν, water density ρ and downstream channel water depth h t , Rotating trapezoidal gate length L 1 , Height from gate rotation axis to channel bottom plate L 2 , the functional relationship is formula (2)

[0016] f S (Q S ,m,θ,H 0 ,B,g,v,ρ,h t ,L1,L2)=0 (2).

[0017] Among them, the preset dimensional analysis method is:

[0018] With ρ, g, H 0 As basic physical variables, length [T], mass [M] and time [L] are selected as basic dimensions. According to the π theorem and the principle of dimensional harmony, we can obtain:

[0019]

[0020] In the formula It has the same dimension as 1 / Re (Re is the Reynolds number) and can be ignored in free surface flow. Therefore, the above formula can be transformed into:

[0021]

[0022] According to the gate outflow formula in traditional hydraulics, the flow rate Q is proportional to the water head H before the gate. 0 0.5 , the above formula can be rewritten as:

[0023]

[0024] The first relationship between the flow rate Q and the rotation angle θ is:

[0025] Free outflow:

[0026] Flood outflow:

[0027] Flow coefficient μ 1 The expression is:

[0028] Flow coefficient μ 2 The expression is:

[0029] Where, flow rate Q; flow coefficient μ; cross-sectional area of ​​the rotating gate outflow A; gravity acceleration g; water head H before the gate 0 ; Channel slope coefficient m; Flow width B; Rotation angle θ; Downstream channel water depth h t ; Rotating trapezoidal gate length L 1 ; Height from gate rotation axis to channel bottom plate L 2 ;

[0030] The expression of A is: A=b(L 2 -L 1 cosθ)+2(L 2 -L 1 cosθ)mH 0 -(L 2 -L 1 cosθ) 2 m

[0031] In the formula, the channel bottom width is b; the rotation angle is θ; the channel slope coefficient is m; the water head before the gate is H 0 ; Rotating trapezoidal gate length L 1 ; Height from gate rotation axis to channel bottom plate L 2 ;

[0032] The expression of B is: B = b + 2mH 0

[0033] In the formula, the channel bottom width is b; the channel slope coefficient is m; the water head before the gate is H 0 ;

[0034] The method for obtaining the physical parameter test data involved in the first relationship is as follows:

[0035] In the free outflow test, based on the fixed slope coefficient m, channel bottom width b, gravity acceleration g, and rotating trapezoidal gate length L 1 , Height from gate rotation axis to channel bottom plate L 2 , changing the upstream water depth and the opening of the rotating trapezoidal gate, and obtaining the test data of the water head H before the gate 0 , gate rotation angle θ and free outflow flow;

[0036] In the flooding outflow experiment, based on the fixed slope coefficient m, channel bottom width b, gravity acceleration g, and rotating trapezoidal gate length L 1 , Height from gate rotation axis to channel bottom plate L 2 , changing the upstream and downstream water depths and the opening of the rotating trapezoidal gate, and obtaining the test data of the water head H before the gate 0 , downstream channel water depth ht, gate rotation angle θ and submerged outflow flow.

[0037] The numerical fitting method is as follows: the test data is fitted with mathematical formulas according to formula (11) and formula (12), the flow coefficient relationship is substituted into formula (9) and formula (10), and the second relationship between the flow rate Q and the rotation angle θ is derived.

[0038] The beneficial effects brought by the present invention are: fully considering the opening and closing methods and gate shape characteristics of the rotary opening and closing trapezoidal gate, being able to accurately control the flow of the rotary opening and closing trapezoidal gate, and providing technical guarantee for precise irrigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described below in conjunction with the accompanying drawings.

[0040] Figure 1 It is a front view of the rotating trapezoidal gate flow through an embodiment of the present invention.

[0041] Figure 2 Schematic diagram of the test system layout of an embodiment of the present invention.

[0042] Figure 3 This is a free outflow fitting effect diagram of an embodiment of the present invention.

[0043] Figure 4 This is a submerged outflow fitting effect diagram of an embodiment of the present invention.

[0044] Figure 5 4 is a relative error distribution diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0045] This embodiment provides an operation method of a rotary opening and closing trapezoidal gate for controlling flow, with the Yarnaizi Reservoir in Turpan as a test point:

[0046] 1. Apply the dimensional analysis method to the physical parameters that affect the flow rate Q, and obtain the first relationship between the flow rate Q and the rotation angle θ:

[0047] Free outflow:

[0048] Flood outflow:

[0049] Flow coefficient μ 1 The expression is:

[0050] Flow coefficient μ 2 The expression is:

[0051] Where, flow rate Q; flow coefficient μ; cross-sectional area of ​​the rotating gate outflow A; gravity acceleration g; water head H before the gate 0 ; Channel slope coefficient m; Flow width B; Rotation angle θ; Downstream channel water depth h t ; Rotating trapezoidal gate length L 1 ; Height from gate rotation axis to channel bottom plate L 2 ;

[0052] The expression of A is: A=b(L 2 -L 1 cosθ)+2(L 2 -L 1 cosθ)mH 0 -(L 2 -L 1 cosθ) 2 m

[0053] In the formula, the channel bottom width is b; the rotation angle is θ; the channel slope coefficient is m; the water head before the gate is H 0 ; Rotating trapezoidal gate length L 1 ; Height from gate rotation axis to channel bottom plate L 2 ;

[0054] The expression of B is: B = b + 2mH 0

[0055] In the formula, the channel bottom width is b, the channel slope coefficient is m, and the water head before the gate is H.0 .

[0056] 2. Build a proportionally reduced test system based on the existing gate system to obtain test data of the physical parameters involved in the first relationship:

[0057] Figure 1 FIG. 1 is a front view of a rotating trapezoidal gate according to an embodiment of the present invention. Figure 2 As shown in the figure, the test system includes ① elevated constant pressure water tank, ② centrifugal pump, ③ water pipeline, ④ flow control valve, ⑤ stabilizing tank, ⑥ trapezoidal channel, ⑦ rotating trapezoidal gate, ⑧ tailwater gate, ⑨ triangular thin-walled water measuring weir, ⑩ drainage channel, Underground reservoirs, etc. Water flows from underground reservoirs to elevated constant pressure pools through centrifugal pumps. After the overflow of the pool stabilizes, it enters a 3m long water stabilization tank through a water delivery pipe with a diameter of 200mm. A suspended fence is set 1m before the outlet to stabilize water to reduce turbulence at the entrance of the trapezoidal channel. The trapezoidal channel is 6m long and 0.15m wide at the bottom of the channel. It is installed on a steel pipe frame with a longitudinal slope of i=1 / 1000. When selecting the installation location of the rotating trapezoidal gate, in order to ensure that the upstream water flow through the channel is in a slow flow state, there is a long transition section upstream of the rotating trapezoidal gate, which is more than 3 times the width of the channel. The rotating trapezoidal gate is arranged at a distance of 2.5m from the water inlet. After passing through the tailwater gate, the water flows into the water measuring weir for flow measurement, with a measurement accuracy of ±1.4%. Then it flows back to the underground reservoir through the drainage channel in the laboratory to complete the entire system cycle.

[0058] The test is divided into free outflow test and submerged outflow test. In the free outflow test, the test data of the water head H before the gate is obtained by changing the rotation angle of the rotating trapezoidal gate and the opening of the flow control valve. 0 , gate rotation angle θ and free outflow flow; in the submerged outflow test, by changing the opening of the tailwater gate at the end of the trapezoidal channel, the opening of the rotating gate, and the opening of the flow control valve, the test data of the water head H before the gate is obtained. 0 , downstream channel water depth ht, gate rotation angle θ and submerged outflow flow.

[0059] 3. Input the test data into the gate control system, and derive the second relationship between the flow rate Q and the rotation angle θ by combining the first relationship and the test data through the preset numerical fitting method:

[0060] The numerical fitting method is: to fit the test data according to formula (11) and formula (12) to obtain the fitting effect. Figure 3 , Figure 4 , an equation with high model fitting accuracy and simple form was selected, and the flow coefficient relationship was substituted into formula (9) and formula (10), and the second relationship between flow Q and rotation angle θ was derived:

[0061] Free outflow:

[0062] Flood outflow:

[0063] In order to evaluate the performance of the obtained flow formula, the flow calculation value Q is obtained according to formulas (13) and (14): c and compare it with the measured flow rate Q o By comparison, the absolute value of the relative error δ (δ = |Q 0 -Q c | / Q 0 ) and (L 2 -L 1 cosθ) / H 0 The relationship is plotted in Figure 5 The average relative error (ARE) is calculated as shown in formula (15). The average relative errors (ARE) of free outflow formula (13) and submerged outflow formula (14) are 2.01% and 2.07%, respectively, both lower than 3%, indicating that the calculated values ​​are highly consistent with the measured values, the formula has good performance, and the calculation accuracy is high.

[0064]

[0065] Where: Q 0 is the measured flow value; Q c is the calculated flow value; N is the number of test data sets.

[0066] 4. The flow required for the actual operation and the measured physical parameters of the existing gate are input into the gate control system, and the gate control system controls the gate to open and rotate θ according to the second relationship:

[0067] The channel slope coefficient m = 1.5, channel bottom width b = 0.4m, gravity acceleration g = 9.8m / s, and rotating trapezoidal gate length L of the test point of the Yarnaizi Reservoir in Turpan area are set. 1 =11.12m, height from gate rotation axis to channel bottom plate L 2 =9.5m, these fixed parameters are input into the gate control system;

[0068] In the free outflow state, input the actual operation required flow rate Q and the measured water head H before the gate. 0 ;

[0069] In the submerged outflow state, input the actual operation required flow rate Q and the measured head H before the gate. 0 and downstream channel water depth ht;

[0070] The rotating gate control system controls the gate opening rotation angle θ according to the second relationship, that is, formula (13) and (14), as shown in Table 1:

[0071] Table 1

[0072]

[0073] The present invention is not limited to the specific technical solutions described in the above embodiments. In addition to the above embodiments, the present invention may also have other implementation modes. For those skilled in the art, any technical solutions formed by any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for operating a rotary opening and closing trapezoidal gate for controlling flow, characterized in that: The following steps are involved: Applying the dimensional analysis method to the physical parameters that affect the flow rate Q, the first relationship between the flow rate Q and the rotation angle θ is obtained; Building a proportionally reduced test system based on the existing gate system to obtain test data of the physical parameters involved in the first relational expression; The test data is input into the gate control system, and a second relationship between the flow rate Q and the rotation angle θ is derived by combining the first relationship and the test data through a preset numerical fitting method; The flow required for actual operation and the measured physical parameters of the existing gate are input into the gate control system, and the gate control system controls the gate to open the rotation angle θ according to the second relationship.

2. The method for operating a rotary opening and closing trapezoidal gate for controlling flow rate according to claim 1, characterized in that: The physical parameters affecting the flow rate Q are as follows: The effective parameters in the free outflow phenomenon are: channel slope coefficient m, rotation angle θ, water head H0 in front of the gate, flow width B, gravity acceleration g, dynamic viscosity coefficient ν and water density ρ, rotating trapezoidal gate length L1, height L2 from the gate rotation axis to the channel bottom plate, and the functional relationship is formula (1) f F (Q F ,m,θ,H0,B,g,υ,ρ,L1,L2)=0 (1) The effective parameters in the flooding outflow phenomenon are: channel slope coefficient m, rotation angle θ, head H0 before the gate, flow width B, gravity acceleration g, dynamic viscosity coefficient ν, water density ρ and downstream channel depth h t , the length of the rotating trapezoidal gate L1, the height from the gate rotation axis to the channel bottom plate L2, the functional relationship is formula (2) f S (Q S ,m,θ,H0,B,g,υ,ρ,h t ,L1,L2)=0 (2)。 3. The method for operating a rotary opening and closing trapezoidal gate for controlling flow rate according to claim 2, characterized in that: The default dimensional analysis method is: Taking ρ, g, H0 as basic physical variables, length [T], mass [M] and time [L] as basic dimensions, according to the π theorem and the principle of dimensional harmony, we can obtain: In the formula It has the same dimension as 1 / Re (Re is the Reynolds number) and can be ignored in free surface flow. Therefore, the above formula can be converted to: According to the gate outflow formula in traditional hydraulics, the flow rate Q is proportional to the water head H0 before the gate. 0.5 , the above formula can be rewritten as: The first relationship between the flow rate Q and the rotation angle θ is: Free outflow: Flood outflow: The expression of flow coefficient μ1 is: The expression of flow coefficient μ2 is: Where, flow rate Q; flow coefficient μ; cross-sectional area of ​​the rotating gate outflow A; gravity acceleration g; head H0 before the gate; channel slope coefficient m; flow width B; rotation angle θ; downstream channel water depth h t ; Length of the rotating trapezoidal gate L1; Height from the gate rotation axis to the channel bottom plate L2; The expression of A is: A = b(L2-L1cosθ)+2(L2-L1cosθ)mH0-(L2-L1cosθ) 2 m In the formula, the channel bottom width is b; the rotation angle is θ; the channel slope coefficient is m; the water head before the gate is H0; the length of the rotating trapezoidal gate is L1; the height from the gate rotation axis to the channel bottom plate is L2; The expression of B is: B = b + 2mH0 In the formula, the channel bottom width is b; the channel slope coefficient is m; and the water head before the gate is H0.

4. The method for operating a rotary opening and closing trapezoidal gate for controlling flow rate according to claim 3, characterized in that: The method for obtaining the physical parameter test data involved in the first relationship is as follows: In the free outflow test, based on the fixed slope coefficient m, channel bottom width b, gravity acceleration g, rotating trapezoidal gate length L1, and the height L2 from the gate rotation axis to the channel bottom plate, the upstream water depth and the rotating trapezoidal gate opening were changed to obtain the test data of the water head H0 before the gate, the gate rotation angle θ, and the free outflow flow rate; In the submerged outflow experiment, based on the fixed slope coefficient m, channel bottom width b, gravitational acceleration g, rotating trapezoidal gate length L1, and height L2 from the gate rotation axis to the channel bottom plate, the upstream and downstream water depths and the rotating trapezoidal gate opening were changed to obtain the test data of the head H0 before the gate, the water depth ht of the downstream channel, the gate rotation angle θ, and the submerged outflow flow.

5. The method for operating a rotary opening and closing trapezoidal gate for controlling flow rate according to claim 3 or 4, characterized in that: The numerical fitting method is: fitting the test data with mathematical formulas according to formula (11) and formula (12), substituting the flow coefficient relationship into formula (9) and formula (10), and deriving a second relationship between the flow Q and the rotation angle θ.

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