A peak value calculation method for water flow force of a triangular gate under moving water

Abstract

The application discloses a calculation method of water flow force peak value of a triangular gate under dynamic water, and respectively provides a method for calculating water flow force peak value of the triangular gate under non-constant flow opening and closing conditions and bidirectional water head operation conditions. The method can be used for calculating the water flow force peak value of the triangular gate under the dynamic water (non-constant flow) opening and closing conditions, and is helpful for optimizing the gate opening and closing control strategy and guaranteeing the safety and stability of the gate operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ship lock hydraulics calculation, and more particularly to a method for calculating the peak water flow force of a triangular gate in dynamic water opening and closing. BACKGROUND

[0002] The triangular gate has the unique advantages of bidirectional water load bearing capacity and flexible dynamic water opening and closing. However, during the dynamic water opening and closing process, the triangular gate will generate a large water flow force, and the dynamic characteristics (especially the peak value) directly affect the safety of the gate opening and closing system.

[0003] Existing document 1: Jiang Yusong. Calculation of triangular gate opening and closing force under different conditions [J]. China Water Transport, 2019, 19: (11): 99-100, based on the Ship Lock Gate Design Specification (JTJ 308-2003), the triangular gate opening and closing force calculation method under the conditions of flat water opening and closing, gate gap water conveyance and dynamic water through gate is optimized, but the stress calculation value is larger than the actual stress when the gate is in small opening degree. In addition, this document points out that the triangular gate opening and closing under dynamic water conditions, due to the complex structure of the gate and the lock chamber, the water flow pattern is complex, and the opening and closing force fluctuates greatly, and the water flow force calculation still needs further study.

[0004] Existing document 2: Patent No. ZL202411190381.4, the invention name is a method for calculating the opening and closing force of a triangular gate in small opening degree gap water conveyance under positive water conveyance, which can accurately calculate the opening and closing force of a triangular gate in small opening degree gap water conveyance (constant flow) under positive water conveyance. However, this method has limitations in applicability, and is only applicable to constant flow gate gap water conveyance conditions, and does not consider the non-constant flow dynamic water opening and closing conditions of the triangular gate and the bidirectional water head operation conditions.

[0005] At present, the design of triangular gate structure mainly focuses on static force analysis, and it is difficult to capture the dynamic law of water flow force when the gate is opened and closed in dynamic water, especially the accurate calculation formula of the peak value of water flow force. Therefore, establishing a method for accurately calculating the peak value of water flow force of triangular gate in dynamic water opening and closing has important theoretical significance and engineering application value for improving the scientificity of triangular gate design, ensuring the safety of ship lock operation and reducing the operation risk. SUMMARY

[0006] The present application aims to provide a method for calculating the peak value of water flow force of a triangular gate in dynamic water opening and closing, which can accurately calculate the peak value of water flow force of a triangular gate in dynamic water opening and closing.

[0007] The present application adopts the following technical solutions:

[0008] A method for calculating the peak value of water flow force of a triangular gate in dynamic water opening, comprising:

[0009] S1, determining the flow direction;

[0010] S2, obtaining corresponding hydraulic parameter data, including submerged water depth, upstream and downstream water level difference, and gate chamber flow velocity;

[0011] S3, if the flow direction in step S1 is positive head, the peak water flow force acting on the triangular gate during the opening process is calculated according to the following formula:

[0012] ;

[0013] If the flow direction in step S1 is reverse head, the peak water flow force acting on the triangular gate during the opening process is calculated according to the following formula:

[0014] ;

[0015] In the formula: Fw 1max 、 Fw 2max The peak water flow force under positive head and reverse head respectively; H The submerged water depth is Δ h The upstream and downstream water level difference is Δ

[0016] 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.

[0017] 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.

[0018] A method for calculating the peak water flow force of a triangular gate during the closing process in running water, comprising:

[0019] S1, determining the flow direction;

[0020] S2, obtaining corresponding hydraulic parameter data, including submerged water depth, upstream and downstream water level difference, and gate chamber flow velocity;

[0021] S3, if the flow direction in step S1 is positive head, the peak water flow force acting on the triangular gate during the closing process is calculated according to the following formula:

[0022] ;

[0023] If the flow direction in step S1 is reverse head, the peak water flow force acting on the triangular gate during the closing process is calculated according to the following formula:

[0024] ;

[0025] In the formula: Fw 3max 、 Fw 4max are the peak values of water flow force under positive and negative water head respectively; Fr is the Froude number.

[0026] Further, Fr = u / ( gH ) 0.5 , u is the flow velocity in the gate chamber, u > 0 indicates that water flows from upstream to downstream, u ≤ 0 indicates that water flows from downstream to upstream

[0027] Advantages of the present application:

[0028] The present application respectively provides a method for calculating the peak values of water flow force of a triangular gate under non-constant flow opening and closing conditions and bidirectional water head operating conditions. The method can be used to calculate the peak values of water flow force of a triangular gate under dynamic water conditions (non-constant flow) when opening and closing, which helps to optimize the gate opening and closing control strategy and ensure the safety and stability of the gate operation. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is the physical model of Example 1, wherein a is a plan layout and b is a section layout;

[0030] Figure 2 is a curve graph of the peak values of water flow force when opening the gate under dynamic water and the dimensionless upstream and downstream water level difference, wherein a is a positive water head and b is a negative water head;

[0031] Figure 3 is a curve graph of the peak values of water flow force when closing the gate under dynamic water and the Froude number, wherein a is a positive water head and b is a negative water head. DETAILED DESCRIPTION

[0032] Example 1

[0033] In this example, a new triangular gate driven by hydraulic opening and closing in China is taken as the research object, and the physical model is as follows Figure 1As shown in (a) and (b), the physical model has a total length of 28.00 m, with the upstream approach channel 1 being 3.00 m long, the downstream approach channel 2 being 2.85 m long, and the lock chamber 3 being 1.35 m wide. Both upstream and downstream of the physical model are equipped with inlets and outlets. 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 flow rate. Horizontal water channels 4 are arranged both upstream and downstream to control the water level. The outlet of the horizontal water channel 4 is connected to the side return water corridor, which leads directly to the underground reservoir 5 for water recycling.

[0034] A functional relationship between the hydrodynamic forces during the opening and closing of the triangular sluice gate was established using dimensional analysis. The main physical quantities that may affect the hydrodynamic forces during the opening and closing of the triangular sluice gate include: submerged water depth. H ∆ h Flow rate u Fluid density p Dynamic viscosity coefficient µ Surface tension coefficient δ Gravitational acceleration g Therefore, the functional relationship characterizing the dynamic water flow force during the opening and closing of the triangular sluice gate can be expressed as:

[0035]

[0036] We select mass [M], time [T], and length [L] as the basic units of measurement. p, g, H As basic physical variables, according to π From the theorem and the principle of dimensional harmony, we can obtain:

[0037]

[0038] In the formula π The value can be taken as its reciprocal as needed without changing its dimensionless property, and can be written as:

[0039]

[0040] Solving for the force of water flow F w ,have to:

[0041]

[0042] The final expression for the hydrodynamic force can be written as:

[0043]

[0044] Where Re is the Reynolds number. ，Fr For Froude number , We It is a Weber number.

[0045] Re(Reynolds number): viscous force vs. inertial force (reflects viscous effects of fluid);

[0046] We (Weber number): inertial force vs. surface tension (reflects surface tension effects);

[0047] Fr (Froude number): inertial force vs. gravity (reflects gravity effects).

[0048] According to the flow characteristics of the triangular gate opening and closing operation: the triangular gate flow is usually high Reynolds number flow (such as large-scale gate, high-speed water flow), the inertial force is much larger than the viscous force, and the contribution of viscous effect to the total water flow force Fw can be ignored. The triangular gate flow is large in scale (such as river channel, ship lock), and gravity dominates the free surface behavior. Surface tension is only significant at a small scale (such as capillary wave), and its effect on large-scale flow can be ignored.

[0049] The above formula (5) can be simplified as:

[0050]

[0051] From the above analysis, the water flow force characteristics in the dynamic water opening and closing process of the triangular gate are related to the factors such as the water level difference between upstream and downstream and the flow velocity. Specifically, in the dynamic water opening condition, the water flow force is mainly controlled by the water level difference between upstream and downstream; and in the dynamic water closing process, it is mainly affected by the flow velocity in the gate chamber.

[0052] This embodiment measures the peak value of water flow force under the conditions of opening the gate under the positive water head and the submerged water depth of the gate H 6.75m, 7.75m, 8.75m respectively; measures the peak value of water flow force under the conditions of opening the gate under the negative water head and the submerged water depth of the gate H 6.0m, 7.0m, 8.0m respectively; the peak value of dynamic water opening water flow force under the conditions of positive water head and negative water head and the dimensionless water level difference change process between upstream and downstream are shown in Figure 2 . The scatter distribution of the peak value of dynamic water opening water flow force shows that the peak value of water flow force and the dimensionless water level difference between upstream and downstream are linearly related. Linear fitting is performed on the peak value of dynamic water opening water flow force under the conditions of positive water head and negative water head, and formulas (7) and (8) are obtained, and the correlation coefficients are R 2 = 0.95, R 2 = 0.96.

[0053] Condition 1. When opening the gate under the positive water head:

[0054]

[0055] Condition 2. Reverse water head dynamic water opening:

[0056]

[0057] The physical model was measured under the positive water head, and the gate submergence water depth H was 7.75 m and 8.75 m, respectively. The peak water flow force was measured under the physical model under the reverse water head, and the gate submergence water depth H was 7.0 m and 8.0 m, respectively. The peak water flow force under the conditions of positive water head and reverse water head and the Froude number change process are shown in Figure 3 Under the condition of positive water head, the peak water flow force and the Froude number showed an exponential relationship, and an exponential function was established by nonlinear regression to obtain formula (9), and the correlation coefficient R 2 = 0.97; under the condition of reverse water head, the peak water flow force and the Froude number showed a linear relationship, and a linear function was established by linear fitting to obtain formula (10), and the correlation coefficient R 2 = 0.98.

[0058] Condition 3. Positive water head dynamic water closing:

[0059]

[0060] Condition 4. Reverse water head dynamic water closing:

[0061]

[0062] In order to evaluate the performance of the obtained peak water flow force calculation formula, the peak water flow force calculation value Fw c of Example 1 was calculated according to formula (7)-(10), respectively, and compared with the measured peak water flow force Fw 0 in Example 1, the average relative error ARE was calculated, see formula (11), the average relative error ARE of formula (7)-(10) was 4.89%, 4.74%, 3.62%, and 3.67%, respectively, all lower than 5%, indicating that the consistency between the calculation value and the measured value was high, the formula performance was good, and the calculation precision was high.

[0063]

[0064] In formula (11) Fw c , the peak water flow force calculated by formula (7)-(10), respectivelyFw 1max 、 Fw 2max 、 Fw 3max 、 Fw 4max ; Fw0is the measured peak water flow force, N is the number of test data sets.

[0065] Example 2

[0066] This example uses the prototype observation data of a large triangular gate in China to verify the applicability of formulas (7)-(10). Since the ship lock was officially put into operation in 1980, it has been an important shipping channel in southern Jiangsu. The lock chamber is 230.00 m long, the entrance is 20.00 m wide, the sill depth is 4.00 m, the upstream approach channel is 1.50 km long, and it intersects with the Yangtze River. The parameters involved in formulas (7)-(11) were measured and collected. Fw 0、 Δh 、 u prototype observation data.

[0067] The above-mentioned prototype observation data is used for verification. Figure 2 and Figure 3 The triangular scatter plot prototype observation data in this example 2 corresponds to the measured peak water flow force F w0 , the submerged depth of the positive water head is about 6.50 m, and the submerged depth of the reverse water head is about 6.10 m. From Figure 2 、 3 , it can be seen that the triangular scatter plot distribution is consistent with the fitting curve obtained by the model in example 1, and the consistency is high. In addition, the prototype observation data Δh 、 u obtained by this example is substituted into formulas (7)-(10), and the calculated peak water flow force Fw c is obtained, as shown in Table 1.

[0068] Table 1 Verification of Prototype Observation Data

[0069]

[0070] According to the results in Table 1, the relative errors are relatively small.

Claims

1. A method for calculating the peak value of water flow force acting on a moving triangular gate, characterized in that, Comprising: S1, determining the flow direction; S2, obtaining the corresponding hydraulic parameter data, including the submerged water depth, the upstream and downstream water level difference and the gate chamber flow velocity; S3, if the flow direction in step S1 is the positive head, then the peak water flow force on the triangular gate during the dynamic water opening process is calculated according to the following formula: ，∆ h ＞0； If the flow direction in step S1 is the reverse head, then the peak water flow force on the triangular gate during the dynamic water opening process is calculated according to the following formula: ，∆ h ≤ 0； In the formula: Fw 1max , Fw 2max are the peak values of the water flow force under the positive and negative water heads, respectively; H is the submerged water depth; h is the water level difference between upstream and downstream; ρ is the fluid density; g is the gravitational acceleration.

2. The method according to claim 1, wherein, The upstream-downstream water level difference, i.e., 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.

3. The method according to claim 1, wherein, 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.

4. A method for calculating the peak water flow force of a moving water on a tripping gate, characterized in that, Comprising: S1, determining the flow direction; S2, obtaining the corresponding hydraulic parameter data, including the submerged water depth, the upstream and downstream water level difference and the gate chamber flow velocity; S3, if the flow direction in step S1 is the positive head, then the peak water flow force on the triangular gate during the dynamic water closing process is calculated according to the following formula: ， u ＞0； If the flow direction in step S1 is the reverse head, then the peak water flow force on the triangular gate during the dynamic water closing process is calculated according to the following formula: ， u ≤ 0； wherein: Fw 3max , Fw 4max are the peak values of the water flow force under the positive and negative water heads, respectively; Fr is the Froude number; ρ is the fluid density; g is the gravitational acceleration.

5. The method according to claim 4, wherein, Froude number Fr = u / ( gH ) 0.5 , u is the flow velocity in the lock chamber, u > 0 indicates that water flows from upstream to downstream, u ≤ 0 indicates that water flows from downstream to upstream.

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