Method for calculating peak value of flowing water opening and closing water flow acting force of triangular gate

Abstract

The invention discloses a triangular gate dynamic water opening and closing water flow acting force peak value calculation method, and provides a method for calculating the water flow acting force peak value of a triangular gate under a non-constant flow opening and closing working condition and a bidirectional water head operation condition. The method can be used for calculating the water flow acting force peak value when the triangular gate is opened and closed under the flowing water condition (non-constant flow), optimization of a gate opening and closing control strategy is facilitated, and the safety and stability of gate operation are guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic calculation of ship locks, and more particularly to a method for calculating the peak value of the water flow acting on the dynamic opening and closing of a triangular gate. Background Art

[0002] Triangular gates offer the unique advantages of bidirectional water load bearing capacity and flexible opening and closing with dynamic water flow. However, during the dynamic water flow opening and closing process, triangular gates generate significant flow forces, and their dynamic characteristics (especially peak forces) directly affect the safety of the gate opening and closing system.

[0003] Existing literature 1: Jiang Yusong. Calculation of opening and closing force of triangular gate under different working conditions [J]. China Water Transport, 2019,19: (11): 99-100. Based on the "Design Specifications for Ship Locks and Valves" (JTJ 308-2003), the calculation method of the opening and closing force of triangular gates under three conditions of flat water opening and closing, gate gap water delivery, and gate dynamic water flow was optimized. However, this method has a large force calculation value when the gate is operating at a small opening, and there is a large error with the actual force. In addition, the literature points out that when the triangular gate is opened and closed under dynamic water conditions, the complex flow pattern is complex due to the complex structure of the gate and the gate chamber, and the opening and closing force fluctuates greatly. The calculation of water flow force still needs further research.

[0004] Existing Document 2: Patent No. ZL202411190381.4, titled "A Method for Calculating the Opening and Closing Force of a Triangular Gate with Forward Water Delivery and a Small Gate Slit." This method accurately calculates the opening and closing forces of a triangular gate during forward water delivery and water delivery with a small gate gap (constant flow). However, this method is limited in its applicability and is only applicable under constant-flow gate gap conditions. It does not consider the triangular gate's opening and closing conditions with non-constant water flow or bidirectional head operation.

[0005] Currently, triangular gate structural design focuses on static analysis, but the dynamic laws of the flow forces acting on the gate during dynamic water opening and closing are difficult to capture, especially the lack of an accurate calculation formula for the peak flow force. Therefore, establishing a method that can accurately calculate the peak flow force acting on the triangular gate during dynamic water opening and closing has important theoretical significance and engineering application value for improving the scientific nature of triangular gate design, ensuring the safety of ship lock operation, and reducing operational risks. Summary of the Invention

[0006] The present invention aims to provide a method for calculating the peak value of the water flow force acting on the dynamic water opening and closing of a triangular gate, which can realize accurate calculation of the peak value of the water flow force acting on the dynamic water opening and closing of a triangular gate.

[0007] The present invention adopts the following technical solutions: A method for calculating the peak value of the water flow force during dynamic water opening of a triangular gate, comprising: S1. Determine the incoming flow direction; S2, obtain corresponding hydraulic parameter data, including submerged water depth, upstream and downstream water level difference and gate chamber flow velocity; S3, if the flow direction in step S1 is positive head, calculate the peak water flow force on the triangular gate during the dynamic water opening process according to the following formula: ; If the flow direction in step S1 is reverse head, calculate the peak water flow force on the triangular gate during the dynamic water opening process according to the following formula: ; In the formula: FW 1max 、 FW 2max The peak water flow force under positive head and reverse head respectively; H The submerged water depth; h The upstream and downstream water level difference.

[0008] Further, the upstream and downstream water level difference is the upstream water level value minus the downstream water level value, Δ h > 0 indicates that the upstream water level value is greater than the downstream water level value, Δ h ≤ 0 indicates that the upstream water level value is less than or equal to the downstream water level value.

[0009] Further, the submerged water depth is the depth of the gate structure submerged in water, that is, the vertical distance from the gate bottom plate to the water surface.

[0010] A peak water flow force calculation method for dynamic water closing of a triangular gate, comprising: S1, determine the flow direction; S2, obtain corresponding hydraulic parameter data, including submerged water depth, upstream and downstream water level difference and gate chamber flow velocity; S3, if the flow direction in step S1 is positive head, calculate the peak water flow force on the triangular gate during the dynamic water closing process according to the following formula: ; If the flow direction in step S1 is reverse head, calculate the peak water flow force on the triangular gate during the dynamic water closing process according to the following formula: ; In the formula: FW 3max 、 FW 4max The peak water flow force under positive head and reverse head respectively; Fr The Froude number.

[0011] Further, Fr = u / ( gH ) 0.5 , u is the chamber flow velocity, u >0 means water flows from upstream to downstream, u ≤ 0 means water flows from downstream to upstream Beneficial effects of the present invention: The present invention provides methods for calculating the peak value of the water flow force acting on the triangular gate under non-constant flow opening and closing conditions and bidirectional head operating conditions. This method can be used to calculate the peak value of the water flow force acting on the triangular gate when opening and closing under dynamic water conditions (non-constant flow), which helps to optimize the gate opening and closing control strategy and ensure the safety and stability of the gate operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The physical model of Example 1, wherein a is a plan view and b is a cross-sectional view; Figure 2 The graph is the relationship between the peak force of the water flow when the dynamic water valve is opened and the dimensionless upstream and downstream water level difference, where a is the positive head and b is the reverse head; Figure 3 This is the relationship curve between the peak force of the dynamic water closed-door flow and the Froude number, where a is the positive head and b is the reverse head. DETAILED DESCRIPTION

[0013] Example 1

[0014] This embodiment takes a newly built hydraulically driven triangular gate in China as the research object, and its physical model is as follows: Figure 1 As shown in Figures (a) and (b), the total length of the physical model is 28.00 m. The upper approach channel 1 is 3.00 m long, the downstream approach channel 2 is 2.85 m long, and the lock chamber 3 is 1.35 m wide. Inlets and outlets are designed upstream and downstream of the physical model. The model uses a 400 mm diameter spiral steel pipe for water supply, with a butterfly valve installed at the inlet end to control the inlet flow. A horizontal water trough 4 is located upstream and downstream to control the water level. The outlet of the horizontal water trough 4 is connected to a lateral return water gallery, which directly connects to an underground reservoir 5 for water circulation.

[0015] Through dimensional analysis, a functional relationship is established for the water flow force during the opening and closing of the triangular gate. The main physical quantities that may affect the water flow force during the opening and closing of the triangular gate are: H , upstream and downstream water level difference ∆ h , flow rate u , fluid density ρ , dynamic viscosity coefficient µ , surface tension coefficient δ , gravitational acceleration g Therefore, the functional relationship that characterizes the water flow force of the triangular gate dynamic water opening and closing can be expressed as:

[0016] Select mass [M], time [T] and length [L] as basic dimensions, ρ, g, H is a basic physical variable, according to π Theorem and the principle of dimensional harmony yield:

[0017] In the formula π The value can be taken as its reciprocal as needed without changing its dimensionless number properties, and can be written as:

[0018] Solving for water flow forces F w ,have to:

[0019] The final water flow force expression can be written as:

[0020] Where Re is the Reynolds number ，Fr Froude number ,We is the Weber number.

[0021] Re (Reynolds number): viscous force vs. inertial force (reflects the influence of fluid viscosity); We (Weber number): Inertial force vs. surface tension (reflects the influence of surface tension); Fr (Froude number): Inertial force vs. gravity (reflects the influence of gravity).

[0022] According to the flow characteristics of the triangular gate opening and closing operation: the triangular gate flow is usually a high Reynolds number flow (such as large-scale gates, high-speed water flow), the inertial force is much greater than the viscous force, and the viscous effect has a great impact on the total water flow force. FW The contribution of is negligible. At larger scales (e.g., river channels and ship locks) through triangular gates, gravity dominates the free surface behavior. Surface tension is only significant at microscales (e.g., capillary waves) and its influence on larger-scale flows is negligible.

[0023] The above formula (5) can be simplified to obtain:

[0024] The above analysis shows that the flow force characteristics during the dynamic opening and closing of the triangular gate are related to factors such as the upstream and downstream water level difference and flow velocity. Specifically, during the dynamic opening process, the flow force is primarily controlled by the upstream and downstream water level difference, while the dynamic closing process is primarily influenced by the flow velocity in the gate chamber.

[0025] The physical model was measured under the positive water head, the gate submerged water depth H The peak value of water flow force under the conditions of 6.75m, 7.75m, 8.75m gate opening respectively; the physical model was measured under the negative water head, the gate submerged water depth H The peak value of water flow force under the conditions of 6.0m, 7.0m, 8.0m gate opening respectively; the peak value of water flow force under the conditions of positive water head and negative water head and the change process of non-dimensional upstream and downstream water level difference are shown in Figure 2 The peak value of water flow force under the conditions of positive water head and negative water head and the change process of non-dimensional upstream and downstream water level difference are shown in R 2 = 0.95、 R 2 = 0.96.

[0026] Condition 1. Positive water head dynamic water opening:

[0027] Condition 2. Negative water head dynamic water opening:

[0028] The physical model was measured under the positive water head, the gate submerged water depth H The peak value of water flow force under the conditions of 7.75m, 8.75m gate closing respectively; the physical model was measured under the negative water head, the gate submerged water depth H The peak value of water flow force under the conditions of 7.0m, 8.0m gate closing respectively; the peak value of water flow force under the conditions of positive water head and negative water head and the change process of Froude number are shown in Figure 3 Under the condition of positive water head, the peak value of water flow force and Froude number show an exponential relationship, an exponential function is established by nonlinear regression, formula (9) is obtained, and the correlation coefficient R 2 = 0.97; under the condition of negative water head, the peak value of water flow force and Froude number show a linear relationship, a linear function is established by linear fitting, formula (10) is obtained, and the correlation coefficient R 2 = 0.98.

[0029] Condition 3. Positive water head dynamic water closing:

[0030] Condition 4. Negative water head dynamic water closing:

[0031] In order to evaluate the performance of the obtained water flow force peak calculation formula, the water flow force peak calculation values ​​of this embodiment 1 are calculated according to formulas (7)-(10) respectively: FW c and compare it with the peak value of the water flow force measured in Example 1 FW 0 and calculate the average relative error ( ARE ), see formula (11), the average relative error of formula (7)-(10) ( ARE ) were 4.89%, 4.74%, 3.62% and 3.67% respectively, all lower than 5%, indicating a high consistency between the calculated and measured values, good formula performance and high calculation accuracy.

[0032]

[0033] In formula (11) FW c That is, the peak value of the water flow force calculated by formulas (7)-(10) FW 1max 、 FW 2max 、 FW 3max 、 FW 4max ; Fw0 is the measured peak value of water flow force, and N is the number of test data groups.

[0034] Example 2 This example uses the prototype observation data of a large domestic triangular lock to verify the applicability of formulas (7)-(10). Since its official opening in 1980, this ship lock has been an important shipping channel in southern Jiangsu. The lock chamber is 230.00m long, the gate is 20.00m wide, the threshold water depth is 4.00m, and the upstream pilot channel is 1.50km long and intersects with the Yangtze River. The parameters involved in formulas (7)-(11) are collected by field measurement. FW 0. Δh 、 u Prototype observation data.

[0035] The prototype observation data obtained above were used for verification. Figure 2 and Figure 3 The observed data of the middle triangle scatter prototype is the actual measured value of the peak value of the water flow force corresponding to Example 2 F w0 , the flooding depth of the positive head is about 6.50 m, and the flooding depth of the reverse head is about 6.10 m. Figure 2 、 3It can be seen that the triangular scatter distribution is highly consistent with the fitting curve obtained by the model in Example 1, and the trends are consistent. Δh 、 u Substitute into formula (7)-(10) and calculate the peak value of water flow force FW c , as shown in Table 1.

[0036] Table 1 Prototype observation data verification

[0037] According to the results in Table 1, it can be seen that the relative errors are relatively small.

Claims

1. A method for calculating the peak value of the water flow force during the dynamic water opening of a triangular gate, characterized in that: include: S1. Determine the incoming flow direction; S2. Obtain corresponding hydraulic parameter data, including flooding depth, upstream and downstream water level difference, and chamber flow velocity; S3. If the incoming flow direction in step S1 is positive head, calculate the peak value of the water flow force on the triangular gate during the dynamic water opening process according to the following formula: ； If the incoming flow direction in step S1 is reverse head, the peak value of the water flow force on the triangular gate during the dynamic water opening process is calculated according to the following formula: ； Where: FW 1max 、 FW 2max are the peak values ​​of water flow force under positive head and reverse head respectively; H is the flooding depth; Δ h The difference in water level between upstream and downstream.

2. A method for calculating the peak value of the water flow force during the dynamic water opening of a triangular gate according to claim 1, characterized in that: The upstream and downstream water level difference is the upstream water level minus the downstream water level, Δ h >0 means the upstream water level is greater than the downstream water level, Δ h ≤ 0 means the upstream water level is less than or equal to the downstream water level.

3. The method for calculating the peak value of the water flow force during the dynamic water opening of a triangular gate according to claim 1 is characterized in that: The submerged water depth is the depth to which the gate structure is immersed in water, that is, the vertical distance from the gate bottom plate to the water surface.

4. A method for calculating the peak value of the water flow force acting on the dynamic water closing gate of a triangular gate, characterized in that: include: S1. Determine the incoming flow direction; S2. Obtain corresponding hydraulic parameter data, including flooding depth, upstream and downstream water level difference, and chamber flow velocity; S3. If the incoming flow direction in step S1 is positive head, calculate the peak value of the water flow force on the triangular gate during the dynamic water closing process according to the following formula: ； If the incoming flow direction in step S1 is reverse head, the peak value of the water flow force on the triangular gate during the dynamic water closing process is calculated according to the following formula: ； Where: FW 3max 、 FW 4max are the peak values ​​of water flow force under positive head and reverse head respectively; Fr is the Froude number.

5. A method for calculating the peak value of the water flow force of a triangular gate dynamic water closing gate according to claim 4, characterized in that: Froude number Fr = u / ( gH ) 0.5 , u is the chamber flow velocity, u >0 means water flows from upstream to downstream, u ≤ 0 means water flows from downstream to upstream.

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