A method for controlling the operation of a rotating on-off trapezoidal gate for flow

Abstract

The application relates to a running method for controlling the flow of a rotating opening and closing trapezoidal gate, which comprises the following steps: firstly, using the dimension analysis method on the physical parameters affecting the flow Q to obtain a first relationship between the flow Q and the rotation angle theta; secondly, according to the existing gate system, building a test system with the same proportion, obtaining the test data of the physical parameters involved in the first relationship; thirdly, inputting the test data into the gate control system, and through a preset numerical fitting method, combining the first relationship and the test data to deduce a second relationship between the flow Q and the rotation angle theta; and finally, inputting the required flow in actual operation and the measured physical parameters of the existing gate into the gate control system, and the gate control system controls the opening rotation angle theta of the gate according to the second relationship. The application fully considers the opening and closing mode and the shape characteristics of the rotating opening and closing trapezoidal gate, can accurately control the flow of the rotating opening and closing trapezoidal gate, and provides technical support for accurate irrigation.

Description

TECHNICAL FIELD

[0001] The application relates to a gate operation method, in particular to an operation method of a rotating opening and closing trapezoidal gate for controlling flow. BACKGROUND

[0002] In an irrigation system, the trapezoidal gate arranged in the trapezoidal channel has the advantages of low construction difficulty, because the trapezoidal gate does not need to build a gate chamber and auxiliary buildings connected with the gate chamber. Moreover, for some old irrigation systems, corresponding trapezoidal gates can be selected according to the size of the original channel, without the need for large-scale reconstruction of the channel, and the engineering cost is relatively small.

[0003] By controlling the water flow through the gate at different flow rates, the water requirements of different crops at different growth stages can be met, and the application prospect is good, but how to accurately control the flow of the rotating opening and closing trapezoidal gate is still a difficulty. Researchers have conducted a lot of research on how to calculate the flow of rectangular gates and arc-shaped gates, and the corresponding flow formula has been relatively perfect. For the less common trapezoidal gate, the research group of the inventors has also carried out a number of studies, such as the Chinese invention with the publication number CN114626316A, which discloses a flow calculation method for free outflow of a vertical opening and closing trapezoidal flat gate.

[0004] However, compared with the vertical lifting of the vertical opening and closing trapezoidal gate, the flow boundary conditions of the rotating opening and closing trapezoidal gate change, the rotating trapezoidal gate leaf is oblique to the water flow, which avoids the direct collision between the water flow and the gate, thereby reducing the energy loss caused by impact and friction, and the conversion amount of water flow energy changes. In addition, due to the difference in opening and closing mode, the calculation formula of the water flow section area under the rotating opening and closing mode is completely different from that of the vertical opening and closing trapezoidal gate, so the calculation method of the vertical opening and closing trapezoidal gate cannot be simply applied to the rotating opening and closing trapezoidal gate. Therefore, a different flow calculation method needs to be used to accurately calculate the gate flow and control the water flow.

[0005] Therefore, the problem of how to control the opening and closing of the rotating opening and closing trapezoidal gate to obtain accurate outflow flow needs to be solved. SUMMARY

[0006] The technical problem to be solved by the application is to provide an operation method of a rotating opening and closing trapezoidal gate, which can accurately calculate the outflow flow of the rotating opening and closing trapezoidal gate and accurately control the flow.

[0007] To solve the above technical problems, the technical solution provided by the application is: an operation method of a rotating opening and closing trapezoidal gate for controlling flow,

[0008] The first relationship between the flow Q and the rotation angle θ is obtained by using the dimensional analysis method on the physical parameters affecting the flow Q.

[0009] According to the existing gate system, a test system with the same scale is built to obtain the test data of the physical parameters involved in the first relationship;

[0010] The test data are input into the gate control system, and the second relationship between the flow 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 actual required flow and the measured physical parameters of the existing gate are input into the gate control system, and the gate control system controls the opening rotation angle θ of the gate according to the second relationship.

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

[0013] The effective parameters in the free outflow phenomenon are the channel side slope coefficient m, the rotation angle θ, the upstream water head H0, the flow width B, the gravitational acceleration g, the dynamic viscosity coefficient v, the water density ρ, the length of the rotating trapezoidal gate L1, and the height from the gate rotation axis to the channel bottom plate L2, and the functional relationship is formula (1)

[0014] f F (Q F ,m,θ,H0,B,g,v,ρ,L1,L2)=0 (1)

[0015] The effective parameters in the submerged outflow phenomenon are the channel side slope coefficient m, the rotation angle θ, the upstream water head H0, the flow width B, the gravitational acceleration g, the dynamic viscosity coefficient v, the water density ρ, and the downstream channel water depth h t , the length of the rotating trapezoidal gate L1, and the height from the gate rotation axis to the channel bottom plate L2, and the functional relationship is formula (2)

[0016] f S (Q S ,m,θ,H0,B,g,v,ρ,h t ,L1,L2)=0 (2)。

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

[0018] Taking ρ, g, and H0 as the basic physical variables, length [T], mass [M], and time [L] are selected as the basic dimensions, and according to the π theorem and the dimensional harmony principle, the following can be obtained:

[0019]

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

[0021]

[0022] Referring to the formula of the sluice outlet flow in traditional hydraulics, the flow Q is proportional to the water head H0 in front of the sluice 0.5 The above formula can be rewritten as:

[0023]

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

[0025] Free outflow:

[0026] Submerged outflow:

[0027] The expression of the flow coefficient μ1 is:

[0028] The expression of the flow coefficient μ2 is:

[0029] In the formula, the flow Q; the flow coefficient μ; the water cross-section area A of the rotating sluice outflow; the gravitational acceleration g; the water head H0 in front of the sluice; the channel slope coefficient m; the flow width B; the rotation angle θ; the downstream channel water depth h t ; the rotating trapezoidal sluice length L1; the height L2 from the sluice rotation axis to the channel bottom plate;

[0030] The expression of A is: A = b (L2-L1cosθ) + 2 (L2-L1cosθ) mH0 - (L2-L1cosθ) 2 m

[0031] In the formula, the channel bottom width b; the rotation angle θ; the channel slope coefficient m; the water head H0 in front of the sluice; the rotating trapezoidal sluice length L1; the height L2 from the sluice rotation axis to the channel bottom plate;

[0032] The expression of B is: B = b + 2mH0

[0033] In the formula, the channel bottom width b; the channel slope coefficient m; the water head H0 in front of the sluice;

[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, the channel bottom width b, the gravitational acceleration g, the rotating trapezoidal sluice length L1, and the height L2 from the sluice rotation axis to the channel bottom plate, the upstream water depth and the rotating trapezoidal sluice opening are changed to obtain the test data of the water head H0 in front of the sluice, the sluice rotation angle θ, and the free outflow flow;

[0036] In the submerged outflow experiment, based on the fixed slope side coefficient m, the channel bottom width b, the gravity acceleration g, the rotating trapezoidal gate length L1, the height L2 from the gate rotating shaft to the channel bottom plate, the upstream and downstream water depths and the rotating trapezoidal gate opening are changed, and the test data gate water head H0, downstream channel water depth ht, gate rotating angle θ and submerged outflow flow are obtained.

[0037] The numerical fitting method is that the test data are fitted according to formula (11) and formula (12), the flow coefficient relationship formula is brought into formula (9) and formula (10), and the second relationship formula between the flow Q and the rotating angle θ is derived.

[0038] The beneficial effects brought by the present application are that the opening and closing mode and the gate shape characteristics of the rotating opening and closing trapezoidal gate are fully considered, the flow of the rotating opening and closing trapezoidal gate can be accurately controlled, and technical support is provided for accurate irrigation. BRIEF DESCRIPTION OF DRAWINGS

[0039] The present application will be further described below in combination with the drawings.

[0040] Figure 1 It is a front view of the rotating trapezoidal gate of the embodiment of the present application.

[0041] Figure 2 It is a test system layout of the embodiment of the present application.

[0042] Figure 3 It is a free outflow fitting effect diagram of the embodiment of the present application.

[0043] Figure 4 It is a submerged outflow fitting effect diagram of the embodiment of the present application.

[0044] Figure 5 It is a relative error distribution diagram of the embodiment of the present application. DETAILED DESCRIPTION

[0045] The present embodiment provides a running method of a rotating opening and closing trapezoidal gate for controlling flow, taking the Yalnaizi Reservoir in the Turpan area as a test point:

[0046] 1. The dimensional analysis method is used for the physical parameters affecting the flow Q, and the first relationship formula between the flow Q and the rotating angle θ is obtained:

[0047] Free outflow:

[0048] Submerged outflow:

[0049] The expression of the flow coefficient μ1 is:

[0050] The expression of the flow coefficient μ2 is:

[0051] In the formula, the flow Q; the flow coefficient μ; the water section area A of the outlet flow of the rotating gate; the gravity acceleration g; the water head H0 in front of the gate; the channel slope coefficient m; the flow width B; the rotation angle θ; the downstream channel water depth h t ; the rotating trapezoidal gate length L1; the height L2 from the gate rotation axis to the channel bottom plate;

[0052] The expression of A is: A = b (L2 - L1 cos θ) + 2 (L2 - L1 cos θ) m H0 - (L2 - L1 cos θ) 2 m

[0053] In the formula, the channel bottom width b; the rotation angle θ; the channel slope coefficient m; the water head H0 in front of the gate; the rotating trapezoidal gate length L1; the height L2 from the gate rotation axis to the channel bottom plate;

[0054] The expression of B is: B = b + 2 m H0

[0055] In the formula, the channel bottom width b, the channel slope coefficient m, and the water head H0 in front of the gate.

[0056] 2. An experiment system of equal proportion reduction is built according to the existing gate system, and the experiment data of the physical parameters involved in the first relationship are obtained:

[0057] Figure 1 As shown in the flow passage front view of the rotating trapezoidal gate of the embodiment of the present application, Figure 2 the experiment system comprises ① an overhead constant pressure pool, ② a centrifugal pump, ③ a water conveying pipeline, ④ a flow control valve, ⑤ a water stabilizing tank, ⑥ a trapezoidal channel, ⑦ a rotating trapezoidal gate, ⑧ a tail water gate, ⑨ a triangular thin wall water weir, and ⑩ a drainage channel, an underground reservoir and the like. The water flow is conveyed from the underground reservoir to the overhead constant pressure pool through the centrifugal pump, and after the pool overflow is stable, the water flow enters the water stabilizing tank with a length of 3 m through the water conveying pipeline with a diameter of 200 mm. A suspended grid water stabilizer is arranged at a position 1 m in front of the outlet of the water stabilizing tank, so as to reduce the turbulence at the inlet of the trapezoidal channel. The trapezoidal channel has a length of 6 m, a channel bottom width of 0.15 m, and is installed on a steel pipe frame. The channel longitudinal slope i = 1 / 1000. When the installation position of the rotating trapezoidal gate is selected, in order to ensure that the water flow in the upstream passing channel is in a slow flow state, there is a long transition section with a length greater than 3 times the width of the channel upstream of the rotating trapezoidal gate, and the rotating trapezoidal gate is arranged at a position 2.5 m away from the water inlet. After the water flow passes through the tail water gate, the water flow flows into the water weir for flow measurement, and the measurement accuracy is ±1.4%. Subsequently, the water flow is returned to the underground reservoir through the laboratory drainage channel, and the whole system circulation is completed.

[0058] The experiment is divided into free outflow experiment and submerged outflow experiment. In the free outflow experiment, the test data of the water head H0 in front of the gate, the gate rotation angle θ and the free outflow flow are obtained by changing the rotation angle of the rotating trapezoidal gate and the opening of the control valve. In the submerged outflow experiment, the test data of the water head H0 in front of the gate, the water depth ht of the downstream channel, the gate rotation angle θ and the submerged outflow flow are obtained by changing the opening of the tail gate at the end of the trapezoidal channel, the opening of the rotating gate and the opening of the control valve.

[0059] 3. The test data are input into the gate control system, and the second relationship between the flow Q and the rotation angle θ is derived by the preset numerical fitting method, the first relationship and the test data:

[0060] The numerical fitting method is that the test data are mathematically fitted according to the formula (11) and the formula (12), and the fitting effect is shown in Figure 3 、 Figure 4 The equation with high model fitting precision and simple form is selected, the flow coefficient relationship is brought into the formula (9) and the formula (10), and the second relationship between the flow Q and the rotation angle θ is derived:

[0061] Free outflow:

[0062] Submerged outflow:

[0063] In order to evaluate the performance of the obtained flow formula, the flow calculation value Q c is obtained according to the formula (13) and (14), and is compared with the measured flow Q o , the relationship between the absolute value of the relative error δ (δ = |Q0-Q c | / Q0) and (L2-L1cosθ) / H0 is plotted in Figure 5 , and the average relative error (ARE) is calculated, see formula (15). The average relative error (ARE) of the free outflow formula (13) and the submerged outflow formula (14) is 2.01% and 2.07% respectively, which is lower than 3%, indicating that the consistency between the calculation value and the measured value is high, the formula performance is good, and the calculation precision is high.

[0064]

[0065] Wherein: Q0 is the measured flow value; Q c is the calculation flow value; N is the number of test data groups.

[0066] 4. The required flow of 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 rotation θ according to the second relationship:

[0067] The fixed parameters of the sluice control system are inputted, including the channel slope coefficient m=1.5 of the Yarnai Zi Reservoir test point in Turpan region, the channel bottom width b=0.4 m, the gravity acceleration g=9.8 m / s, the length L1 of the rotating trapezoidal sluice gate is 11.12 m, and the height L2 from the rotating shaft of the sluice gate to the channel bottom plate is 9.5 m;

[0068] In the free outflow state, the required flow Q through the sluice gate for actual operation and the measured water head H0 in front of the sluice gate are inputted again;

[0069] In the submerged outflow state, the required flow Q through the sluice gate for actual operation, the measured water head H0 in front of the sluice gate and the downstream channel water depth ht are inputted again;

[0070] The rotating sluice gate control system controls the opening rotation angle θ of the sluice gate according to the second relationship, i.e. formula (13), (14), as shown in Table 1:

[0071] Table 1

[0072]

[0073] The present application is not limited to the specific technical solutions described in the above embodiments, and in addition to the above embodiments, the present application can also have other implementation manners. For those skilled in the art, any modifications, equivalent replacements, improvements, etc. formed within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of operating a rotary on-off trapezoidal gate for controlling flow, characterized in that, It comprises the following steps: The dimension analysis method is used to obtain a first relationship between the flow Q and the rotation angle θ based on the physical parameters affecting the flow Q. The effective parameters in the free outflow phenomenon are: the channel side slope coefficient m, the rotation angle θ, the water head H0 in front of the gate, the flow width B, the gravity acceleration g, the dynamic viscosity coefficient v, the water density ρ, the length of the rotating trapezoidal gate L1, and the height L2 from the gate rotation shaft to the channel bottom plate, and the functional relationship is formula (1) The dimension analysis method is: (1) The effective parameters in the phenomenon of submerged outflow are: channel side slope coefficient m, rotation angle θ, water head in front of the gate H0, flow width B, gravity acceleration g, dynamic viscosity coefficient v, water density ρ and downstream channel water depth h t The function relationship is formula (2) (2) The dimension analysis method is: The first relationship between the flow Q and the rotation angle θ is: (3) (4) where With the same dimension as 1 / Re, which can be neglected in free surface flow, Re is the Reynolds number, thus the above equation can be transformed into: (5) (6) Referring to the sluice outlet flow formula in traditional hydraulics, the flow rate Q is proportional to the water head H0 in front of the sluice 0.5 The above formula can be rewritten as: (7) (8) The expression of B is: B = b + 2mH0 Free outflow: (9) Submerged outflow: (10) The expression of the flow coefficient μ1 is: (11) The expression of the flow coefficient μ2 is: (12) In the formula, flow Q; flow coefficient μ; water cross-section area A of the rotating gate outflow; gravitational acceleration g; water head H0 in front of the gate; channel slope coefficient m; flow width B; rotation angle θ; downstream channel water depth h t ; rotating trapezoidal gate length L1; height L2 from the gate rotation axis to the channel bottom plate; The expression of A is: ; wherein b is the channel bottom width; θ is the rotation angle; m is the channel slope coefficient; H0 is the water head in front of the gate; L1 is the length of the rotating trapezoidal gate; L2 is the height from the gate rotation axis to the channel bottom plate; In the formula, b is the channel bottom width, m is the channel side slope coefficient, and H0 is the water head in front of the gate. 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 side coefficient m, the channel bottom width b, the gravity acceleration g, the length of the rotating trapezoidal gate L1, and the height L2 from the gate rotation shaft to the channel bottom plate, the upstream water depth and the rotating trapezoidal gate opening are changed to obtain the test data of the water head H0 in front of the gate, the gate rotation angle θ, and the free outflow flow; In the submerged outflow test, based on the fixed slope side coefficient m, the channel bottom width b, the gravity acceleration g, the length of the rotating trapezoidal gate L1, and the height L2 from the gate rotation shaft to the channel bottom plate, the upstream and downstream water depths and the rotating trapezoidal gate opening are changed to obtain the test data of the water head H0 in front of the gate, the downstream channel water depth ht, the gate rotation angle θ, and the submerged outflow flow; According to the existing gate system, a test system with the same proportion is built to obtain the test data of the physical parameters involved in the first relationship; The test data is input into the gate control system, and a second relationship between the flow Q and the rotation angle θ is derived by combining the first relationship and the test data through a preset numerical fitting method; The numerical fitting method is: the test data is mathematically fitted according to formula (11) and formula (12), the flow coefficient relationship formula is brought into formula (9) and formula (10), and the second relationship between the flow Q and the rotation angle θ is derived; The actual operation required flow 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. ​

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