A method for predicting the flow of a pier block fishway with fishway slope

Abstract

The application discloses a method for predicting the flow of a pier block fishway with a fishway slope, which comprises the following steps: performing dimension analysis on the pier block fishway; verifying the numerical simulation method, performing physical model test and numerical calculation on the pier block fishway, collecting the water depth at the front end of the first middle pier block, and performing data comparison to obtain a reasonable and effective calculation software setting method; performing numerical simulation on the pier block fishways with different slopes through the obtained computational fluid dynamics setting method, and processing the output water depth and flow to obtain a flow prediction formula. The pier block fishway with different fishway slopes can be simply and accurately predicted, the planning rationality of arranging the pier block fishway in the water conservancy project is improved, and the problem that fish cannot effectively migrate in the fishway due to the change of the fishway bottom slope is effectively avoided.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering, and specifically relates to a method for predicting the flow rate of a block-type fishway with a fishway slope. Background Technology

[0002] Fishways are widely used fish passageways, primarily designed to allow fish to migrate upstream through hydraulic barriers such as dams and sluices, thereby mitigating the impact of water conservancy projects on target fish species. They are widely used in dams with medium to low heads. Before entering a fishway, fish need the attraction of a suitable water flow velocity to find the entrance, and within the fishway, they must resist the resistance of the water flow, swimming upstream to eventually reach the upper reaches of the river. Channel and pool-type fishways are widely used types, mainly designed for valuable fish species and economically important migratory fish in rivers. They are typically constructed of reinforced concrete. Based on their structural layout and internal water flow characteristics, fishways can be further classified into: Daniell type, vertical slot type, weir type, submerged orifice type, combined type, and natural-style fishways. The block-type fishway is a type of fishway built by simulating a natural river channel. The internal water flow pattern is closer to that of a natural river channel. Generally, block-shaped columns are evenly distributed in the fishway to provide resistance and increase the flow velocity to allow fish to swim upstream. In order to ensure that fish can use the fishway to reach the upstream, a reasonable flow velocity (flow rate) is one of the key factors that determines the successful passage of fish through the fishway.

[0003] However, with the cumulative erosion of water flow over time, the bottom slope of the fishway is constantly changing. This change has a significant impact on the flow field characteristics, disrupting the fish's adaptability and sensitivity to the water flow, thus causing the fish to no longer migrate through the constructed fishway. Therefore, timely and effective control of the flow velocity in the block-type fishway to improve the flow field and adapt to the fish's living habits is crucial. However, the intrinsic relationship between the flow rate or velocity of the fishway and the bottom slope of the fishway has not yet been studied.

[0004] In recent years, computational fluid dynamics (CFD) and cloud computing technologies have developed rapidly. Due to their advantages such as convenient modeling, direct simulation of prototypes, and good experimental repeatability, numerical simulation methods have become an effective research tool. However, there is currently no method in the technology to predict the flow rate in block-type fishways using numerical experiments. Chinese Patent Publication No. CN110633530A discloses a fishway design method based on computational fluid dynamics and convolutional neural networks. This patent uses computational fluid dynamics to obtain changes in the flow field of the fishway, but its method cannot be used to predict the flow rate of block-type fishways, nor can it reflect the influence of the fishway slope on the flow field. Therefore, how to accurately predict the flow rate of block-type fishways and its quantitative influence on the fishway slope using computational fluid dynamics (CFD) methods is a very worthy research topic, which will effectively guide the design and optimization of block-type fishways in practical engineering. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for predicting the flow rate of block-type fishways with fishway slopes. This method can easily and accurately predict the flow rate of block-type fishways with different fishway slopes, effectively ensuring the economic, stable and sustainable operation of the fishway.

[0006] The technical solution of the present invention: a method for predicting the flow rate of a block-type fishway with a fishway slope, comprising the following steps: Step S1: Conduct a physical model test on the scaled-down block-type fishway with fishway slope to establish a physical model of the block-type fishway. Given any two block-type fishway slopes i j and i o Given the number of blocks N, the flow rates Q of the physical model were measured under different model conditions. m Under the condition of block-type fishway slope i j In the corresponding physical model test, the water depth at the front end of the first middle block of the model block-type fishway was H. t1 and block-type fishway slope i o In the corresponding physical model test, the water depth at the front end of the first middle block of the model block-type fishway was H. t2 ; Step S2: Perform dimensional analysis on the established block-type fishway physical model. The specific dimensional analysis is as follows: The flow rate Q is expressed explicitly using key parameters: Q = F(H, B, s, g), where F is the explicit expression of the equation. Rewriting the explicit expression of flow rate Q as an implicit expression yields F(Q, H, B, s, g) = 0, which contains a total of 5 variables. The unit of flow rate Q is m³ / s, the unit of the side length s of the equilateral block is m, and the unit of gravitational acceleration g is m / s². 2The water depth H at the front of the middle block of the first column of the block-type fishway is in meters, and the width B of the block-type fishway is in meters. Time and length are set as the basic variables, and the five variables are transformed into two π terms. π is a hydraulic dimension relation term. Through dimensional analysis, we obtain π1=(B-2s). a (g) b (Q), π² = (B - 2s) c (g) d (H), Substituting the units of the five variables into π1 and π2 ensures that the unit of π1 is always 1 and the unit of π2 is always 1. π1 is the time-based term and π2 is the length-based term. The calculation yields a=-2.5, b=-0.5, c=-1, d=0. Therefore, π1=Q / [(B-2s)]. 2.5 g 0.5 π2 = H / (B-2s), combining the time fundamental term π1 and the length fundamental term π2, we get Q / [(B-2s)]. 2.5 g 0.5 =α[H / (B-2s)] β Rearranging the terms, we obtain the final explicit expression for the flow rate of the block-type fishway: Q = α[(B-2s)] 2.5 ](g 0.5 [H / (B-2s)] β ; Step S3: Perform numerical simulation calculations on the two scaled-down block fishways with fishway slopes from Step S1, and export the results after the calculations converge. Post-processing is performed using computational fluid dynamics post-processing software, under the same given block-type fishway slope i as in step S1. j and i o Given the number of blocks N, the flow rates Q for different models were calculated. m Under the condition of block-type fishway slope i j In the corresponding numerical simulation, the water depth at the front end of the middle block of the first column of the block-type fishway model is H. c1 and block-type fishway slope i o In the corresponding numerical simulation, the water depth at the front end of the middle block of the first column of the block-type fishway model is H. c2 ; Step S4: The water depth H at the front end of the first intermediate block of the model's block-type fishway, obtained in the numerical simulation in step S3. c1 and H c2 Find the water depth H at the front end of the first middle block of the model's block-type fishway during the physical model test in step S1. t1 and H t2 The calculation condition where the absolute value of the relative error does not exceed 5% at any given time, i.e., |H c1 -H t1 | / Ht1 ≤5% and |H c2 -H t2 | / H t2 If the value is ≤5%, output the corresponding numerical simulation method; Step S5: Given an arbitrary slope i for the block-type fishway and a given number of block rows N, perform computational fluid dynamics calculations on the prototype block-type fishway and output the different prototype flow rates Q of the block-type fishway. p Under the given conditions, the water depth H at the front end of the first intermediate block of the prototype block-type fishway during numerical simulation is... p ; Step S6: Convert the prototype traffic Q p The water depth H at the front end of the first intermediate block of the prototype block-type fishway during numerical simulation. p The difference B-2s between the width of the block-type fishway and twice the side length of the equilateral block is imported into the data processing software of the statistical product and service solution; the final explicit expression of the block-type fishway flow rate in step S2 is Q=α[(B-2s). 2.5 ](g 0.5 [H / (B-2s)] β By performing nonlinear fitting, the flow rate expression for the block-type fishway is obtained under the conditions of arbitrary block slope i and a given number of block rows N: Where k1, k2, k3, k4, and k5 are constant coefficients. The slope i of the block-type fishway and the water depth H at the front end of the middle block of the first column of the block-type fishway are measured and substituted into the expression to obtain the real-time flow rate in the fishway.

[0007] Furthermore, in step S1, a physical model of the block-type fishway is established, with the following specific parameters: The block-type fishway has a geometric length of L, a width of B, a side length of s for each equilateral block, a block height of h, and the blocks are staggered with a longitudinal distance of a. x The horizontal distance is a y The angle between the bottom surface of the block-type fishway and the horizontal plane is γ. The slope i of the block-type fishway is the tangent of the angle γ, i.e., tanγ. N rows of blocks are arranged along the block-type fishway, where the first row of blocks is N=1, and N is an integer. The middle block of the first row of the block-type fishway is located in the exact center of the block-type fishway, and the distance from it to the side walls of the block-type fishway is 'a'. z The two side walls of the block-type fishway are each connected to a protruding block, with a protrusion length of s / 2. The physical model experiment adopted a normal physical model. Taking into account the requirements of the water flow in the square resistance region, the linear scale λ of the physical model was selected. l The physical model is designed using the gravitational similarity criterion, with an angle ratio of λ. γ Flow rate ratio λ v =λ l0.5 Flow ratio λ Q =λ l 2.5 Roughness ratio λ n =λ l 1 / 6 .

[0008] Furthermore, in step S3, numerical simulation calculations are performed on the scaled-down block-type fishway with a fishway slope, specifically as follows: Establish a three-dimensional physical model identical to the scaled-down block-type fishway in step S1, mesh the three-dimensional physical model, output a calculation file with the .mesh extension, and import it into computational fluid dynamics software for numerical calculation. Different mesh scales are used when meshing the three-dimensional physical model to obtain several different mesh schemes. For each mesh scheme, different turbulence models and different numerical algorithms are selected in the computational fluid dynamics software calculation.

[0009] Furthermore, in step S5, the mesh scheme and the Fluent software settings for computational fluid dynamics calculations for the block-type fishway prototype are the same as in step S4.

[0010] Further, step S5 specifically includes: using the numerical simulation method obtained in step S4 to perform computational fluid dynamics calculations on a prototype of a block-type fishway with a given number of block columns N, wherein the slope i of the block-type fishway is at intervals of 1.0%, i.e., 0.0%, 1.0%, 2.0%, 3.0%..., at different prototype flow rates Q. p The water depth H at the front end of the first intermediate block of the prototype block-type fishway was measured under the given conditions during numerical simulation. p .

[0011] Furthermore, in step S6, the steps for determining the constant coefficients k1, k2, k3, k4, and k5 are as follows: Step S61: Convert the prototype flow rate Q corresponding to the slope i of the n block-type fishway. p The water depth H at the front end of the first intermediate block of the prototype block-type fishway during numerical simulation. p Substituting these values ​​into the data processing software for statistical products and services solutions, we obtain the specific values ​​of parameters α and β under each block-type fishway slope i condition. Specifically, fishway slope i1 corresponds to parameter values ​​α1 and β1; fishway slope i2 corresponds to parameter values ​​α2 and β2; fishway slope i3 corresponds to parameter values ​​α3 and β3; fishway slope i4 corresponds to parameter values ​​α4 and β4; ...; fishway slope i n Corresponding parameter value α n and parameter value β n ; Step S62: Calculate the slope i1~i of the block-type fishway obtained in step S61. n and parameter values ​​α1~α n Substituting the data into graphical visualization and data analysis software, a linear fit is performed on the slope i of the block-type fishway and the parameter α to obtain constant coefficients k1 and k2. The slope i1~i2 of the block-type fishway obtained in step S61 are then used as the basis for further analysis. n and parameter values ​​β1~β n By substituting the data into graphical visualization and data analysis software, quadratic fitting was performed on the slope i of the block-type fishway and the parameter β to obtain constant coefficients k3, k4 and k5.

[0012] Furthermore, in step S5, cloud computing technology is introduced into the computational fluid dynamics calculations of the block-type fishway prototype. This approach utilizes cloud computing to improve the accuracy and speed of numerical calculations. The introduction of cloud computing into the prototype's computational fluid dynamics numerical calculations is beneficial because the prototype's calculations involve a massive amount of mesh data, which is difficult to complete with ordinary workstations. Cloud computing also employs high parallelism, significantly improving calculation accuracy and saving computation time.

[0013] The present invention provides a method for predicting the flow rate of a block-type fishway with a fishway slope. This method first verifies the numerical simulation method by performing numerical calculations and physical experiments on a scaled-down physical model of the block-type fishway, and by collecting and comparing the water depth at the front end of the first row of intermediate blocks in the block-type fishway. This yields a reasonable computational fluid dynamics numerical scheme, including mesh generation, a turbulence model, and a numerical method. Since the influence of the fishway slope on numerical accuracy needs to be considered, the present invention ensures that the numerical simulation accuracy of two block-type fishways with different slopes simultaneously meets the specified accuracy requirements when determining the numerical simulation method. Then, computational fluid dynamics calculations are performed on the block-type fishway under prototype conditions using the above numerical scheme, and the corresponding water depth at the front end of the first row of intermediate blocks is output. This invention compares scaled-down physical model experiments with corresponding computational fluid dynamics (CFD) numerical calculations using the physical model. The physical model experiments constrain the numerical calculation method, and the derived numerical calculation method is then used to calculate the water depth at the front of the first intermediate block of the first row of the block-type fishway under prototype conditions. This makes the numerical calculation results under prototype conditions more scientific and effective. Furthermore, the computational fluid dynamics numerical calculation model (the numerical calculation model refers to the model constructed through numerical simulation) built under prototype conditions can meet actual flow conditions, improving the accuracy of computational fluid dynamics numerical simulations and enabling accurate prediction of the real-time flow rate of the block-type fishway with a fishway slope.

[0014] The beneficial effects of the present invention are as follows: The method of predicting the flow rate of block-type fishways with fishway slopes by computational fluid dynamics can easily and accurately predict the flow rate in block-type fishways with different fishway slopes, improve the planning rationality of block-type fishway layout in water conservancy projects, and effectively avoid the problem that changes in the bottom slope of the fishway prevent fish from migrating effectively in the fishway. Attached Figure Description

[0015] Figure 1 The diagram shows the block-type fishway structure: (a) Plan view of the block-type fishway; (b) Cross section AA in the plan view of the block-type fishway. Figure 2 Comparison of water depth at the front of the first row of blocks in the block-type fishway during physical experiments and numerical simulations: (a) Comparison of water depth in the block-type fishway with a slope of i=1.0% during physical experiments and numerical simulations; (b) Comparison of water depth in the block-type fishway with a slope of i=2.0% during physical experiments and numerical simulations. Figure 3 The results for Q~H of the block-type fishway with a slope i = 0.0%~4.0% and a block number N = 6 are given. Figure 4 The parameters α and β are fitted by the graphical visualization and data analysis software Origin when the number of blocks N=6 and the slope i of the fishway is different. (a) The relationship between parameter α and fishway slope i; (b) The relationship between parameter β and fishway slope i. Detailed Implementation

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Example 1 The method for predicting the flow rate of a block-type fishway using computational fluid dynamics in this embodiment includes the following specific steps: Step S1: Conduct a physical model test on the scaled-down block-type fishway to establish a physical model of the block-type fishway; The fishway has a geometric length L of 12m and a width B of 1m. The piers are square blocks with a side length s of 0.18m and a height h of 0.34m. The piers are staggered, with a longitudinal distance a. x and lateral distance a y Both are 0.5m high. The angle between the bottom surface of the block-type fishway and the horizontal plane is 0.6° and 1.1°, respectively. The slope i of the block-type fishway, as the tangent of the angle γ, is 1.0% and 2.0%, respectively. Several rows of blocks are arranged along the fishway according to requirements. The distance between the two blocks in the first row (N=1) is 0.32m. The experiment was conducted under the given conditions of 6 rows of blocks and block-type fishway slopes i=1.0% and i=2.0% (the block-type fishway structure is as follows). Figure 1 As shown), the physical model was measured for different model flow rates Q.m Under the condition that the slope i=1.0% of the block-type fishway corresponds to the physical model test, the water depth at the front end of the middle block of the first row of the model block-type fishway is H. t1 In the physical model test corresponding to a slope i=2.0% for the block-type fishway, the water depth at the front end of the middle block of the first row of the model block-type fishway was H. t2 ; The physical experiment model adopts a normal distribution model. Considering the requirements of the water flow in the square resistance region of the physical experiment model, the linear scale λ of the model is to be selected. l The physical model is designed using the gravitational similarity criterion, with an angle ratio of λ. γ Flow rate ratio λ v =λ l 0.5 Flow ratio λ Q =λ l 2.5 Roughness ratio λ n =λ l 1 / 6 .

[0018] Step S2: Perform dimensional analysis on the established block-type fishway physical model; The flow rate Q is explicitly expressed using key parameters: Q = F(H, B, s, g), where F is the explicit equation. The key parameters are the water depth H at the front of the middle block of the first column of the block-type fishway, the width B of the block-type fishway, the side length s of the equilateral block, and the gravitational acceleration g. Rewriting the explicit expression of flow rate Q as an implicit expression, F(Q, H, B, s, g) = 0, which contains a total of 5 variables. The unit of flow rate Q is m³ / s, the unit of the side length s of the equilateral block is m, and the unit of gravitational acceleration g is m / s². 2 The water depth H at the front of the middle block of the first column of the block-type fishway is in meters, and the width B of the block-type fishway is in meters. Time and length are set as the basic variables. The five variables are transformed into two π terms, where π is a hydraulic dimension term. Through dimensional analysis, we obtain π1 = (B - 2s). a (g) b (Q), π² = (B - 2s) c (g) d (H), Substitute the units of the key parameters into π1 and π2 to ensure that the unit of π1 is always 1 and the unit of π2 is always 1. π1 is the time base term and π2 is the length base term. The calculation yields a=-2.5, b=-0.5, c=-1, d=0, then π1=Q / [(B-2s)] 2.5 g 0.5 π2 = H / (B-2s), combining the time fundamental term π1 and the length fundamental term π2, we get Q / [(B-2s)]. 2.5 g 0.5=α[H / (B-2s)] β Rearranging the terms, we obtain the final explicit expression for the flow rate of the block-type fishway: Q = α[(B-2s)]. 2.5 g 0.5 [H / (B-2s)] β , where α and β are constant coefficients.

[0019] Step S3: Perform numerical simulation calculations on the scaled-down block-type fishway, establish a three-dimensional physical model of the scaled-down block-type fishway, mesh the three-dimensional physical model, output a calculation file with the .mesh extension, import it into the computational fluid dynamics software Fluent for numerical calculation, and export the results after the calculation converges. Post-processing is performed using computational fluid dynamics post-processing software, under the same given block-type fishway slope i as in step S1. j and i o Given the number of blocks N, the flow rates Q for different models were calculated. m Under the condition of block-type fishway slope i j In the corresponding numerical simulation, the water depth at the front end of the middle block of the first column of the block-type fishway model is H. c1 and block-type fishway slope i o In the corresponding numerical simulation, the water depth at the front end of the middle block of the first column of the block-type fishway model is H. c2 ; Different mesh scales were used when meshing the three-dimensional physical model, resulting in several different mesh schemes. For each mesh scheme, different turbulence models and different numerical algorithms were selected in the computational fluid dynamics software Fluent.

[0020] Step S4: Determine the water depth H directly in front of the middle block of the first column of the fishway model obtained in step S3 during numerical simulation. c1 and H c2 Find the water depth H at the front end of the first middle block of the model's block-type fishway during the physical model test in step S1. t1 and H t2 The calculation condition where the absolute value of the relative error does not exceed 5% at any given time, i.e., |H c1 -H t1 | / H t1 ≤5% and |H c2 -H t2 | / H t2 ≤5%, Figure 2This document presents a comparison of the water depth at the front end of the first row of blocks in a block-type fishway during physical experiments and numerical simulations. The absolute values ​​of the relative errors are all less than 5%. The corresponding numerical simulation methods are output, including mesh size, turbulence model, and numerical algorithm. A 1×1×1 hexahedral structured mesh per unit volume is proposed. The turbulence model is a renormalized group model (RNG k-ε), and the governing equations are discretized using the finite volume method (FVM). The diffusion term uses a second-order central difference scheme, the convection term uses a quick scheme, and the pressure and velocity coupling uses a simple coupling algorithm (SIMPLEC). Parallel computation is employed, and the numerical simulation method is the gas-liquid two-phase flow (VOF) method.

[0021] Step S5: Perform computational fluid dynamics calculations on the prototype block-type fishway with different block-type fishway slopes i and a given number of block rows N=6. The block-type fishway slope i is in 1.0% intervals, i.e., 0.0%, 1.0%, 2.0%, 3.0%, and 4.0%, and different prototype flow rates Q. p The water depth H at the front end of the first intermediate block of the prototype block-type fishway was measured under the conditions of numerical simulation. p ; The computational method for the prototype block-type fishway, including the mesh scheme and settings of the Fluent computational fluid dynamics software, employs a 1×1×1 hexahedral structured mesh per unit volume. The turbulence model is a renormalized group model (RNG k-ε), and the governing equations are discretized using the finite volume method (FVM). The diffusion term uses a second-order central difference scheme, the convection term uses a quick scheme, and the pressure-velocity coupling algorithm is a simple coupling algorithm (SIMPLEC). Parallel computation is used, and the numerical simulation method is the gas-liquid two-phase flow (VOF) method. The only difference is that the computational model is changed to a prototype block-type fishway; other computational methods remain the same. Step S4 is a selection and determination process, mainly concerning the mesh size and cloud computing technology. The mesh size does not increase with the scaling of the computational object, avoiding errors due to size enlargement. Introducing cloud technology into the computational fluid dynamics calculation of the block-type fishway prototype improves computational accuracy and saves computational time.

[0022] The prototype calculation results are output after calculation, and then processed by the computational fluid dynamics post-processing software CFD-Post to obtain different prototype flow rates Q. p Under numerical simulation conditions, the water depth H at the front end of the first intermediate block of the prototype block-type fishway was... p The result is as follows Figure 3 As shown; Step S6: The steps in step S5... Figure 3 The prototype flow rate Q was obtained from the computational fluid dynamics calculation shown. pThe water depth H at the front of the first intermediate block of the prototype block-type fishway during numerical simulation was the same as that during numerical simulation. p The difference between the width of the block-type fishway and twice the side length of the equilateral block, B-2s, is imported into Statistical Product and Service Solutions (SPSS) to give the final explicit expression for the block-type fishway flow rate in step S2: Q=α[(B-2s)]. 2.5 ](g 0.5 [H / (B-2s)] β Nonlinear fitting was performed to obtain the parameters α and β under various block-type fishway slope conditions i. Specifically, when i1=0.0%, α1=0.31 and β1=1.56; when i2=1.0%, α2=0.32 and β2=1.51; when i3=2.0%, α3=0.33 and β3=1.50; when i4=3.0%, α4=0.34 and β4=1.51; and when i5=4.0%, α5=0.36 and β5=1.54. The specific fitting steps for the data processing software (SPSS) for Statistical Product and Service Solutions are as follows: 1. First, import the data into SPSS (Statistical Product and Service Solution Data Processing Software). 2. Then perform regression fitting, find the regression in the analysis, and then perform nonlinear fitting to determine the dependent variable and model expression; 3. In the selection process, save the pre-stored initial values, check the residual values, and after fitting, you can obtain reasonable specific values ​​for parameters α and β.

[0023] Then, the different slopes i1~i5 and parameter values ​​α1~α5 of the block-type fishway were substituted into the Origin software for graphical visualization and data analysis. A linear fit was performed between the slope i and parameter α, yielding k1=1.16 and k2=0.31. Next, the different slopes i1~i5 and parameter values ​​β1~β5 of the block-type fishway were substituted into the Origin software for graphical visualization and data analysis. A quadratic fit was performed between the slope i and parameter β, yielding k3=127.14, k4=-5.39, and k5=1.56. Therefore, α=1.36i+0.31, β = 127.14i 2 -5.39i + 1.56, the fitting result is as follows: Figure 4 As shown ( Figure 4The parameters α and β are fitted using the Origin software for graphical visualization and data analysis when the number of blocks N=6 is N, under different block-type fishway slopes i. It should be noted that the effective range of the block-type fishway slope i here is 0.0%≤i≤4%. Therefore, the expression for the final block-type fishway flow rate is: .

[0024] Assuming the slope of the block-type fishway is 1.5%, substituting these values, we can obtain α and β values ​​of 0.33 and 1.51 respectively under this slope condition. Therefore, the real-time flow prediction formula for the block-type fishway is Q=0.33[(B-2s)]. 2.5 ](g 0.5 [H / (B-2s)] 1.51 Assuming the measured water depth H at the front of the first row of piers in the block-type fishway is 0.20m, and the difference B-2s between the width of the block-type fishway and twice the side length of the equilateral pier is 0.64m, then the fishway flow rate at this time is 0.058m³ / s. End.

[0025] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for predicting flow rate in a block-type fishway with a fishway slope, characterized in that: Includes the following steps: Step S1: Conduct a physical model test on the scaled-down block-type fishway with fishway slope to establish a physical model of the block-type fishway. The slope i of the pier block fishway j and i o , under the condition of a given number of pier blocks N, the water depth H m at the front end of the first pier block in the pier block fishway is measured under the condition of different model flow Q j The slope i of the pier block fishway o The water depth H t2 at the front end of the first pier block in the pier block fishway is measured under the condition of different model flow Q 2 ​ Step S2: Perform dimensional analysis on the established block-type fishway physical model. The specific dimensional analysis is as follows: The flow rate Q is expressed explicitly using key parameters: Q = F(H, B, s, g), where F is the explicit expression of the equation. Rewriting the explicit expression of flow rate Q as an implicit expression yields F(Q, H, B, s, g) = 0, which contains a total of 5 variables. The unit of flow rate Q is m³ / s, the unit of the side length s of the equilateral block is m, and the unit of gravitational acceleration g is m / s². 2 The water depth H at the front of the middle block of the first column of the block-type fishway is in meters (m), and the width B of the block-type fishway is in meters (m). Time and length are defined as the basic variables, and the five variables are transformed into two... The term π is a dimensional relation term in hydraulics, obtained through dimensional analysis: π₁ = (B - 2s). a (g) b (Q), π² = (B - 2s) c (g) d (H), Substituting the units of the five variables into π1 and π2 ensures that the unit of π1 is always 1 and the unit of π2 is always 1. π1 is the time-based term and π2 is the length-based term. The calculation yields a=-2.5, b=-0.5, c=-1, d=0. Therefore, π1=Q / [(B-2s)]. 2.5 g 0.5 π2 = H / (B-2s), combining the time fundamental term π1 and the length fundamental term π2, we get Q / [(B-2s)]. 2.5 g 0.5 =α[H / (B-2s)] β ; The final explicit expression of the pier-type fishway flow can be obtained by moving the terms: Q = a[(B - 2s) 2.5 ](g 0.5 ) [H / (B - 2s)] β ; Step S3: Perform numerical simulation calculations on the two scaled-down block fishways with fishway slopes from Step S1, and export the results after the calculations converge. Post-processing by computational fluid dynamics post-processing software, under the same given pier block fishway slope i j and i o , under the condition of a given number of pier block columns N, the different model flow rates Q m Under the condition of a given number of pier block columns N, the different model flow rates Q j The water depth at the front end of the first column of the model pier block fishway is H c1 and the pier block fishway slope i o The water depth at the front end of the first column of the model pier block fishway is H c2 ; Step S4: finding out the calculation condition in which the absolute value of the relative error of the water depth H c1 and H c2 in the numerical simulation in step S3 is less than 5% of the water depth H t1 and H t2 of the first column middle pier of the physical model test in step S1, i.e. c1 -H t1 | / H t1 ≤5% and |H c2 -H t2 | / H t2 ≤5%, and outputting the corresponding numerical simulation method; Step S5: Under the condition of any given block fishway slope i and given block column number N, the prototype of the block fishway is calculated by computational fluid dynamics, and the different prototype flow rates Q of the block fishway are output p Under the condition of any given block fishway slope i and given block column number N, the prototype of the block fishway is calculated by computational fluid dynamics, and the different prototype flow rates Q of the block fishway are output p ; Step S6: The prototype flow Q p The water depth H at the front of the first column of the prototype block fishway p The difference B-2s between the width of the block fishway and twice the length of the side of the equilateral block is introduced into the data processing software of the Statistical Products and Services Solutions. The final explicit expression for the flow rate of the block-type fishway in step S2 is Q=α[(B-2s)]. 2.5 ](g 0.5 [H / (B-2s)] β By performing nonlinear fitting, the flow rate expression for the block-type fishway is obtained under the conditions of arbitrary block slope i and a given number of block rows N: Where k1, k2, k3, k4, and k5 are constant coefficients. The slope i of the block-type fishway and the water depth H at the front end of the middle block of the first column of the block-type fishway are measured and substituted into the expression to obtain the real-time flow rate in the fishway.

2. The method for predicting flow rate of a block-type fishway with a fishway slope according to claim 1, characterized in that: In step S1, a physical model of the block-type fishway is established, with the following specific parameters: The block-type fishway has a geometric length of L, a width of B, a side length of s for each equilateral block, a block height of h, and the blocks are staggered with a longitudinal distance of a. x The horizontal distance is a y The angle between the bottom surface of the block-type fishway and the horizontal plane is γ. The slope i of the block-type fishway is the tangent of the angle γ, i.e., tanγ. N rows of blocks are arranged along the block-type fishway, where the first row of blocks is N=1, and N is an integer. The middle block of the first row of the block-type fishway is located in the exact center of the block-type fishway, and the distance from it to the side walls of the block-type fishway is 'a'. z The two side walls of the block-type fishway are each connected to a protruding block, with a protrusion length of s / 2. The physical model experiment adopted a normal physical model. Taking into account the requirements of the water flow in the square resistance region, the linear scale λ of the physical model was selected. l The physical model is designed using the gravitational similarity criterion, with an angle ratio of λ. γ Flow rate ratio λ v =λ l 0.5 Flow ratio λ Q =λ l 2.5 Roughness ratio λ n =λ l 1 / 6 .

3. The method for predicting flow rate of a block-type fishway with a fishway slope according to claim 2, characterized in that: Step S3 involves numerical simulation calculations for the scaled-down block-type fishway with a fishway slope, specifically as follows: Establish a three-dimensional physical model identical to the scaled-down block-type fishway in step S1, mesh the three-dimensional physical model, output a calculation file with the .mesh extension, and import it into computational fluid dynamics software for numerical calculation. Different mesh scales are used when meshing the three-dimensional physical model to obtain several different mesh schemes. For each mesh scheme, different turbulence models and different numerical algorithms are selected in the computational fluid dynamics software calculation.

4. The method for predicting flow rate of a block-type fishway with a fishway slope according to claim 1, characterized in that: Step S5 specifically includes: using the numerical simulation method obtained in step S4 to perform computational fluid dynamics calculations on a prototype of a block-type fishway with a given number of block columns N, wherein the slope i of the block-type fishway is at intervals of 1.0%, i.e., 0.0%, 1.0%, 2.0%, 3.0%..., at different prototype flow rates Q. p The water depth H at the front end of the first intermediate block of the prototype block-type fishway was measured under the given conditions during numerical simulation. p .

5. The method for predicting flow rate of a block-type fishway with a fishway slope according to claim 4, characterized in that: In step S6, the steps for determining the constant coefficients k1, k2, k3, k4, and k5 are as follows: Step S61: Convert the prototype flow rate Q corresponding to the slope i of the n block-type fishway. p The water depth H at the front end of the first intermediate block of the prototype block-type fishway during numerical simulation. p Substituting these values ​​into the data processing software for statistical products and services solutions, we obtain the specific values ​​of parameters α and β under each block-type fishway slope i condition. Specifically, fishway slope i1 corresponds to parameter values ​​α1 and β1; fishway slope i2 corresponds to parameter values ​​α2 and β2; fishway slope i3 corresponds to parameter values ​​α3 and β3; fishway slope i4 corresponds to parameter values ​​α4 and β4; ...; fishway slope i n Corresponding parameter value α n and parameter value β n ; Step S62: Calculate the slope i1~i of the block-type fishway obtained in step S61. n and parameter values ​​α1~α n Substituting the data into graphical visualization and data analysis software, a linear fit is performed on the slope i of the block-type fishway and the parameter α to obtain constant coefficients k1 and k2. The slope i1~i2 of the block-type fishway obtained in step S61 are then used as the basis for further analysis. n and parameter values ​​β1~β n By substituting the data into graphical visualization and data analysis software, quadratic fitting was performed on the slope i of the block-type fishway and the parameter β to obtain constant coefficients k3, k4 and k5.

6. The method for predicting flow rate of a block-type fishway with a fishway slope according to claim 1, characterized in that: In step S5, cloud computing technology is introduced into the computational fluid dynamics calculation of the block-type fishway prototype.

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