A method for predicting the flow of a fishway of different pier block columns

Abstract

The application discloses a method for predicting the flow of pier block type fishway with different pier block column numbers, which comprises the following steps: firstly, performing physical test on the physical model of the reduced scale pier block type fishway; then, performing numerical calculation on the numerical simulation geometric model which is the same as the physical model; determining the water depth in front of the first column of middle pier blocks according to the relative error of the physical model test and the model numerical simulation being the same as the relative error of the field measurement and the prototype numerical simulation; determining the mathematical relationship between the flow and the water depth in the pier block type fishway through data analysis; and conveniently obtaining the real-time flow in the pier block type fishway through the field test of the water depth in front of the first column of middle pier blocks. The pier block type fishway can avoid unlimited arrangement of the pier block column numbers and waste of the engineering cost, and effectively control the pier block column numbers so that the flow or flow velocity condition in the pier block type fishway can be accurately met, and the problem that fish cannot migrate in the fishway is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of methods for predicting fishway flow, and particularly relates to a method for predicting the flow of a pier block type fishway with different numbers of pier block columns. BACKGROUND

[0002] At present, fishways are widely used fish passage facilities, which mainly serve to allow fish to pass through water conservancy obstacles such as dams and gates, thereby reducing the impact of water conservancy projects on target fish, and are widely used in some medium and low head dams. Before entering the fishway, fish need to be attracted by water flow with an appropriate flow rate to find the entrance of the fishway, and need to resist the resistance of the water flow along the way in the fishway, and finally reach the upstream of the river. The slot type and pool type fishway is a widely used type of fishway, which is mainly designed for valuable fish species and economic migratory fish in rivers, and the building material is generally reinforced concrete structure. According to the form of fishway structure arrangement and the flow characteristics of internal water flow, fishways can be divided into Daniel type, vertical slit type, pool weir type, submerged orifice type, combined type and imitation natural type fishway. The pier block type in the imitation natural type fishway is a fishway built by simulating natural river channels, and the flow pattern in the internal water flow is closer to that in the natural river channel. Generally, the pier columns with square cross section are uniformly distributed in the fishway to provide resistance and increase flow rate for fish to upstream. In order to ensure that fish can reach the upstream by using the fishway, reasonable flow rate (flow) is one of the key factors for fish to successfully pass through the fishway.

[0003] Restoring the longitudinal connectivity of the river channel, protecting the natural ecological system of the river, providing a good habitat for aquatic organisms, and providing a convenient, effective and safe upstream passage for migratory fish have become one of the factors that must be considered when building dams, hydropower stations and other water conservancy projects, and are also one of the hot topics in the field of water conservancy and environmental protection research by many water conservancy scholars.

[0004] Therefore, it is necessary to appropriately arrange block piers to control the flow field. Obviously, the number of piers has a very important influence on the flow rate or flow. With the increase of the number of pier columns, the flow rate or flow in the pier block type fishway decreases, but the internal quantitative relationship between the fishway flow or flow rate and the number of pier columns arranged in the fishway has not been studied.

[0005] In recent years, the computational fluid dynamics (CFD) and cloud computing technology have been developed, and the numerical simulation method is an effective research means due to the advantages of convenient modeling, direct simulation on the prototype, good test repeatability and the like. However, there is no method for predicting the flow of the pier block fishway in the prior art. A fishway design method based on computational fluid dynamics and convolutional neural network is disclosed in Chinese Patent Publication No. CN110633530A, which obtains the change of the fishway flow field by using the computational fluid dynamics technology, but the method cannot be used to predict the flow of the pier block fishway, and cannot reflect the influence of the pier block column number on the flow field of the pier block fishway. Therefore, how to accurately predict the flow of the pier block fishway and the quantitative influence of the pier block column number on the flow of the pier block fishway by using the computational fluid dynamics (CFD) method is a very worthy research topic, which will effectively guide the design and optimization of the pier block fishway in the actual engineering. SUMMARY

[0006] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a method for predicting the flow of a pier block fishway with different pier block column numbers, which can simply and accurately predict the flow of the pier block fishway with different pier block column numbers, and effectively ensure the economic, stable and sustainable operation of the fishway.

[0007] The technical scheme of the present application is a method for predicting the flow of a pier block fishway with different pier block column numbers, comprising the following steps:

[0008] Step S1: performing a physical model test on a pier block fishway model to establish a pier block fishway physical model;

[0009] Given that the slope i of the pier block fishway remains unchanged, under the condition of an arbitrarily given pier block column number N, the water depth H m in front of the first column of the pier block fishway is measured under the condition of different model flow rates Q t of the physical model.

[0010] The physical model test adopts a normal physical model, and the linear scale λ l of the physical model is selected by comprehensively considering the requirements of the resistance square area of the physical model flow, the physical model is designed by using the gravity similarity criterion, the angle ratio λ γ , the flow velocity ratio λ v = λ l 0.5 , the flow ratio λ Q = λ l 2.5 , and the roughness ratio λ n = λ l 1 / 6Since gravity is the main force, the design follows the gravity similarity principle and adopts the parameters and models optimized in this scheme to better simulate the actual engineering situation.

[0011] Step S2: Perform dimensional analysis on the established block fishway physical model to obtain the final explicit expression of the block fishway flow rate Q = ν (w 2.5 )(g 0.5 )(H / w) μ , where ν and μ are constant coefficients, w is the contraction width, g is the acceleration of gravity, and H is the water depth just in front of the middle pier in the first row of the pier-type fishway;

[0012] Step S3: performing numerical simulation calculations on the scaled-down pier-block fishway in step S1, deriving the results after the calculations converge, and outputting the numerical simulation method and the corresponding optimal grid size during the calculations;

[0013] The computational fluid dynamics post-processing software is used to post-process the flow rates Q of different models under the same given pier-type fishway slope i as in step S1 and given the number of pier-type fishway piers N. m Under the condition, the water depth at the front of the middle pier of the first row of the model pier-type fishway is H when the numerical simulation corresponds to the number of pier-type fishway piers N. c ;

[0014] Step S4: The water depth H at the front end of the middle pier of the first row of the model pier-block fishway during the numerical simulation obtained in step S3 is c The water depth at the front end of the middle pier of the first row of the model pier-type fishway during the physical model test in step S1 is H t The relative error is calculated and the model flow series Q is obtained. mj The corresponding relative error sequence η j , η j =(H cj -H tj ) / H tj , the sequence number j represents the model flow Q m , relative error η, physical model test water depth H t and numerical simulation water depth H c The corresponding sequence number;

[0015] Step S5: Under any given pier-type fishway slope i and any given number of pier columns N, perform computational fluid dynamics calculation on the pier-type fishway prototype and output different prototype flow rates Q of the pier-type fishway p Under these conditions, the water depth H at the front end of the middle pier in the first row of the prototype pier-block fishway is p , where the prototype flow Q p is the model traffic sequence Q pj λl 2.5 Q pj = λ l 2.5 Q mj , the water depth sequence corresponding to the water depth at the front end of the first middle pier of the prototype pier-type fishway in the numerical simulation is H pj ;

[0016] Step S6: Combine the model flow series Q mj , the relative error sequence η j and the water depth sequence H pj at the front end of the first middle pier of the prototype pier-type fishway in the numerical simulation fj correction, f represents field measurement, according to the relative error of physical model test and model numerical simulation, the relative error of field measurement and prototype numerical simulation is the same, then η j = (H pj -H fj ) / H fj , that is, (H cj -H tj ) / H tj = (H pj -H fj ) / H fj , H fj = H pj × H tj / H cj ;

[0017] Step S7: Introduce the prototype flow sequence Q pj , the corrected water depth sequence H fj at the front end of the first middle pier of the prototype pier-type fishway in the field measurement and the corresponding contraction width w into the data processing software of statistical product and service solutions (SPSS); perform nonlinear fitting on the final explicit expression of the pier-type fishway flow in step S2 Q = v (w 2.5 )(g 0.5 )(H / w) μ , to obtain the expression of the pier-type fishway flow under the condition of given pier-type fishway slope i and any pier-type fishway column number N, that is, v = AN 2 + BN + C, μ = DN + E, that is, Q = (AN 2 + BN + C) (w 2.5 )(g 0.5 )(H / w) DN+E; wherein A, B, C, D, E are constant coefficients, the number of pier block N of the pier block type fishway and the water depth H of the front end of the middle pier block in the first column of the pier block type fishway are obtained by field measurement, and the real-time flow in the fishway can be obtained by substituting the expression.

[0018] Further, the physical model of the pier block type fishway is established in step S1, and the specific parameters are:

[0019] The geometric length of the pier block type fishway is L, the width is W, the pier block is a square pier with side length s, the pier block height is h, the pier blocks are arranged in staggered manner, the longitudinal distance is a x , the lateral distance is a y , the angle between the bottom surface of the pier block type fishway and the horizontal plane is γ, the slope i of the pier block type fishway is the tangent value of the angle γ between the bottom surface of the pier block type fishway and the horizontal plane, i.e. tan γ, N columns of pier blocks are arranged along the pier block type fishway, wherein the first column of pier blocks is N = 1, N is an integer, and the distance between two pier blocks is w / 2;

[0020] Further, the physical model of the pier block type fishway is analyzed in step S2; the specific dimensional analysis is:

[0021] The flow Q is expressed by the key parameters; Q = F(H, w, g), F is the explicit expression of the equation, and the key parameters are the front end water depth H of the middle pier block in the first column of the pier block type fishway, the contraction width w and the gravitational acceleration g; the explicit expression of the flow Q is rewritten into implicit expression, then F(Q, H, w, g) = 0, wherein the total number of variables is 4, the unit of flow Q is m 3 / s, the unit of contraction width w is m, the unit of gravitational acceleration g is m / s 2 , the unit of the front end water depth H of the middle pier block in the first column of the pier block type fishway is m, time and length are set as basic variables, 4 variables are converted to form 2 π terms through certain conversion, π is a hydrodynamic dimensional relationship term, and π1 = (w) a (g) b (Q), π2 = (w) c (g) d (H) are obtained through dimensional analysis, the units of key parameters are brought into π1 and π2 to ensure π1 = 1 and π2 = 1, π1 is a time-based term, and π2 is a length-based term, a = -2.5, b = -0.5, c = -1, d = 0 are calculated, then π1 = Q / (w 2.5 g 0.5 ), π2 = H / w, the time-based term π1 and the length-based term π2 are combined, then Q / (w 2.5 g 0.5 ) = v(H / w) μ ; moving term can obtain the final explicit expression of the flow of the pier block type fishway.

[0022] Further, the numerical simulation of the scaled pier-type fishway in step S3 and the determination of the optimal grid size are as follows:

[0023] S31: A numerical simulation geometric model of the scaled pier-type fishway is established by using the three-dimensional modeling software SolidWorks, which is the same as that in step S1.

[0024] S32: The grid is divided by using the numerical simulation grid division software ANSYS ICEM, and the grid schemes are G k , where subscript k is the sequence number, taking values of 1, 2, 3, …, the grid overall layout ratio corresponding to the grid scheme is ξ k , the unit of ξ k is dimensionless, and the corresponding maximum grid size is δ k , the unit of δ k is mm, the total amount of the generated grid is M k , the unit of M k is ten thousand, wherein the grid overall layout ratio ξ and the maximum grid size δ decrease with the increase of the sequence number k, and the total amount of the grid M increases with the increase of the sequence number k, the whole grid type is a hexahedral structured grid without any local encryption, and is exported as a calculation file with a suffix name of.mesh;

[0025] S33: The optimal grid parameters of the numerical simulation are determined, the calculation file with the suffix name of.mesh in step S32 is imported into the fluid numerical simulation software Fluent for calculation, the grid schemes G k and G k+1 are calculated, and in the fluid numerical simulation software Fluent, the following settings are made: the turbulence model is a standard turbulence model Standard k-ε, the inlet adopts a velocity inlet condition, the outlet boundary adopts a pressure outlet, the free water surface adopts a pressure inlet, the side wall adopts a wall function, the discrete method of the control equation adopts a finite volume method FVM, the diffusion term adopts a second-order central difference format, the convection term adopts a QUICK format, the coupling of the pressure and the velocity adopts a SIMPLEC algorithm, and the calculation method adopts a volume of fluid method VOF; then data processing is performed by using the numerical simulation post-processing software CFD-Post, the water depth H ck and H ck+1 of the front end of the middle pier in the first column of the model pier-type fishway are collected when the numerical simulation, when H ck ≠ H ck+1 , the grid overall layout ratio and the maximum grid size are reduced, the grid is re-divided, the calculation and data collection and comparison are continued, and when H ck = H ck+1 , the grid overall layout ratio ξ k of the optimal grid scheme G kand the corresponding maximum grid size δ k .

[0026] Further, the determination step of the constant coefficients A, B, C, D, and E in step S7 is as follows:

[0027] Step S71: The numerical simulation method in step S3 and the corresponding optimal grid size are used to perform the computational fluid dynamics calculation on the prototype of the pier block fishway, wherein the number of pier block columns N is rounded, and the water depth H p of the front end of the middle pier block in the first column of the prototype pier block fishway is measured under different prototype flow rates Q p .

[0028] Step S72: The water depth H p of the front end of the middle pier block in the first column of the prototype pier block fishway is corrected using the numerical simulation of each pier block column N in step S6, and the sequence of the water depth H f of the front end of the middle pier block in the first column of the prototype pier block fishway is obtained by correction.

[0029] Step S73: The prototype flow rate Q p corresponding to each pier block column N and the water depth H f of the front end of the middle pier block in the first column of the prototype pier block fishway measured in the field are respectively substituted into the data processing software of the statistical product and service solutions, and the parameters v and parameters μ under the condition of the pier block column N are obtained.

[0030] Step S74: The parameters v and parameters μ under the condition of different pier block column N obtained in step S53 are respectively substituted into the data processing software, and the quadratic term fitting of the pier block column N and the parameters v is performed to obtain the constant coefficients A, the constant coefficients B, and the constant coefficients C, and the linear fitting of the pier block column N and the parameters μ is performed to obtain the constant coefficients D and the constant coefficients E.

[0031] Further, in step S5, cloud computing technology is introduced in the computational fluid dynamics calculation of the prototype of the pier block fishway. In step S71, cloud computing technology is introduced in the computational fluid dynamics calculation of the prototype of the pier block fishway. The introduction of cloud computing in this scheme can improve the accuracy and speed of numerical calculation. The introduction of cloud computing technology in the computational fluid dynamics numerical calculation of the prototype is because the grid amount of the prototype calculation is huge, and it is difficult for ordinary workstations to complete the calculation. There is also a large parallel technology in cloud computing, which significantly improves the calculation accuracy and saves the calculation time.

[0032] Further, in step S5, the grid scheme and the Fluent setting method of the computational fluid dynamics software of the pier block fishway prototype are the same as in step S4.

[0033] The method for predicting the flow of the pier block type fishway of the application comprises the following steps: firstly, physical tests are carried out on the scaled physical model of the pier block type fishway; then, numerical calculation is carried out on the numerical simulation geometric model which is the same as the physical model, and the numerical simulation method is determined before the calculation, including the turbulence model, the grid division, the boundary condition, the discrete method, the calculation format and the numerical method, wherein the grid division has a great influence on the simulation result, and it is necessary to determine the optimal grid size; the numerical simulation method is used to carry out numerical simulation on the scaled physical model, the water depth of the front end of the first column of middle pier blocks of the pier block type fishway is collected, and the relative error between the numerical model and the physical model is determined in combination with the physical model test data; then, the computational fluid dynamics calculation is carried out on the pier block type fishway under the prototype condition through the above numerical scheme, and the water depth of the front end of the first column of middle pier blocks is output; the water depth of the front end of the first column of middle pier blocks is determined according to the relative error between the physical model test and the numerical simulation of the model and the relative error between the field measurement and the numerical simulation of the prototype; finally, the mathematical relationship between the flow and the water depth in the pier block type fishway is determined through data analysis, and the real-time flow in the pier block type fishway can be conveniently obtained by field testing the water depth of the front end of the first column of middle pier blocks.

[0034] The method for predicting the flow of the pier block type fishway of the application can simply and accurately predict the flow in the pier block type fishway with different pier block column numbers, improves the planning rationality of arranging the pier block type fishway in the water conservancy project, can avoid the waste of engineering cost caused by unlimited arrangement of pier block column numbers in the pier block type fishway, and effectively controls the pier block column number to accurately meet the flow or flow rate condition in the pier block type fishway, thereby solving the problem that fish cannot migrate in the fishway. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Figure 1 is a schematic diagram of the pier block type fishway structure, wherein (a) is a plan view of the pier block type fishway, and (b) is a transverse section view of the R-R section in the plan view of the pier block type fishway;

[0036] Figure 2Fig. 2 is a comparison chart of water depth at the front end of the first column of piers in the pier block fishway in physical tests and numerical simulation, (a) a comparison chart of water depth in physical tests and numerical simulation of the pier block fishway with a slope i = 0.0% and a pier column number N = 6; (b) a relative error chart of water depth in physical tests and numerical simulation of the pier block fishway with a slope i = 0.0% and a pier column number N = 6;

[0037] Figure 3 Fig. 3 is a Q-H result of the pier block fishway with a slope i = 0.0% and a pier column number N = 1, 3, 5 and 7;

[0038] Figure 4 Fig. 4 is a parameter v and a parameter μ fitted by a graphic visualization and data analysis software Origin under different pier column numbers N when the slope i = 0.0% of the pier block fishway, (a) a relationship between the parameter v and the pier column number N; (b) a relationship between the parameter μ and the pier column number N. DETAILED DESCRIPTION

[0039] The application will be described in further detail below with reference to the drawings.

[0040] Example 1

[0041] The method for predicting the flow of the pier block fishway by the computational fluid dynamics in the example includes the following specific steps:

[0042] Step S1: a physical model test is performed on the scaled pier block fishway, and a physical model of the pier block fishway is established;

[0043] The fishway has a geometric length L of 12 m, a width W of 1 m, square piers with a side length s of 0.18 m, a height h of 0.34 m, and the piers are arranged with a longitudinal distance a x and a transverse distance a y both of 0.5 m. The pier block fishway has an angle between the bottom surface and the horizontal plane of 0°, a slope i of the pier block fishway of a tangent value of the angle γ of 0.0%, and a plurality of columns of piers arranged along the fishway according to requirements. The distance between the two piers in the first column (N = 1) is w / 2 = 0.32. The test is performed under the conditions of a given pier column number of 6 and a slope i of the pier block fishway of 0.0% (the structure of the pier block fishway is shown in Figure 1 Fig. 1). The model flow Q m of the physical model is measured. The water depth at the front end of the middle pier in the first column of the pier block fishway in the physical model test is H t .

[0044] The physical test model adopts a normal model. Considering the requirement of the flow in the square resistance zone of the physical test model, a model linear scale λ l is selected. The physical model is designed according to the gravity similarity criterion, and the angle ratio λ γ and the flow velocity ratio λ v= λ l 0.5 , flow ratio λ Q = λ l 2.5 , roughness ratio λ n = λ l 1 / 6 .

[0045] Step S2: Dimensional analysis is performed on the established pier-type fishway physical model;

[0046] The flow Q is explicitly expressed by the key parameters; Q=F(H, w, g), F is the explicit expression of the equation, and the key parameters are the water depth H of the front end of the first column of the pier-type fishway, the contraction width w, and the gravitational acceleration g; the explicit expression of the flow Q is rewritten into an implicit expression, that is, F(Q, H, w, g)=0, wherein the total number of variables is 4, the unit of the flow Q is m 3 / s, the unit of the contraction width w is m, the unit of the gravitational acceleration g is m / s 2 , the unit of the water depth H of the front end of the first column of the pier-type fishway is m, time and length are set as the basic variables, the 4 variables are converted to form 2 π terms through certain conversion, π is a dimension relationship term of hydraulics, and dimensional analysis is performed to obtain π1=(w) a (g) b (Q), π2=(w) c (g) d (H), the units of the key parameters are brought into π1 and π2 to ensure that π1=1 and π2=1, π1 is a time-based term, and π2 is a length-based term, calculation is performed to obtain a=-2.5, b=-0.5, c=-1, and d=0, then π1=Q / (w 2.5 g 0.5 ), π2=H / w, the time-based term π1 and the length-based term π2 are combined, and then Q / (w 2.5 g 0.5 )=ν(H / w) μ is obtained; the final explicit expression of the flow of the pier-type fishway is Q=ν(w 2.5 )(g 0.5 )(H / w) μ , wherein ν and μ are constant coefficients.

[0047] Step S3: Numerical simulation calculation is performed on the scaled pier-type fishway in step S1, the results are derived after calculation convergence, and the numerical simulation method and the corresponding optimal grid size during calculation are output;

[0048] The numerical simulation calculation of the scaled pier-type fishway and the determination step of the optimal grid size are specifically as follows:

[0049] S31: The same scale pier block fishway numerical simulation geometric model as in step S1 is established by three-dimensional modeling software SolidWorks;

[0050] S32: The mesh is divided by numerical simulation mesh division software ANSYS ICEM, the mesh schemes are G1, G2, G3 and G4, the corresponding total mesh layout proportions are 4, 3, 2 and 1, and the corresponding maximum mesh sizes are 16, 8, 4 and 2, and the corresponding total amounts of generated meshes are 2 million, 8 million, 16 million and 30 million, the whole mesh type is a hexahedral structured mesh without any local encryption, and the calculation files with the suffix.mesh are exported respectively;

[0051] S33: The optimal numerical simulation mesh parameters are determined, the calculation files with the suffix.mesh in step S32 are imported into the fluid numerical simulation software Fluent for calculation, the mesh schemes G1 and G2 are calculated respectively, the corresponding total mesh layout proportions are 4 and 3, the corresponding maximum mesh sizes are 16 mm and 8 mm, and the corresponding total amounts of meshes are 2 million and 8 million, the fluid numerical simulation software Fluent is set as follows: the turbulence model is a standard turbulence model Standard k-ε, the inlet adopts a velocity inlet condition, the outlet boundary adopts a pressure outlet, the free water surface adopts a pressure inlet, the side wall adopts a wall function, the discrete method of the control equation adopts a finite volume method FVM, the diffusion term adopts a second-order central difference format, the convection term adopts a QUICK format, the coupling of pressure and velocity adopts a SIMPLEC algorithm, and the calculation method adopts a fluid volume method VOF; then data processing is performed by the numerical simulation post-processing software CFD-Post, the water depths of 2.6 cm and 2.4 cm at the front end of the middle pier block in the first column of the model pier block fishway are collected respectively, at this time H c1 is not equal to H c2 , then the mesh schemes G2 and G3 are determined again for calculation, the corresponding total mesh layout proportions are 3 and 2, the corresponding maximum mesh sizes are 8 mm and 4 mm, and the corresponding total amounts of meshes are 8 million and 16 million, the Fluent setting method remains unchanged, the water depths of 2.4 cm and 2.4 cm at the front end of the middle pier block in the first column of the model pier block fishway are collected respectively, at this time H c2 is equal to H c3Equal, output the grid overall layout ratio 3 and the corresponding maximum grid size 8mm of the optimal grid scheme G2; the numerical calculation method is as follows: the turbulence model is a standard turbulence model Standard k-ε, the inlet adopts a velocity inlet condition, the outlet boundary adopts a pressure outlet, the free water surface adopts a pressure inlet, the side wall adopts a wall function, the discrete method of the control equation adopts a finite volume method FVM, the diffusion term adopts a second-order central difference format, the convection term adopts a QUICK format, the coupling of the pressure and the velocity adopts a SIMPLEC algorithm, and the calculation method adopts a volume of fluid method VOF;

[0052] Under the condition that the same given pier block fishway slope i=0.0% as in step S1 and the given pier block fishway pier block column number N=6, the different model flow rates Q m Under the condition that the same given pier block fishway slope i=0.0% as in step S1 and the given pier block fishway pier block column number N=6, the different model flow rates Q c ;

[0053] Step S4: the relative error of the front end water depth H c of the first column middle pier block of the numerical simulation model pier block fishway obtained in step S3 and the front end water depth H t of the first column middle pier block of the physical model test model pier block fishway in step S1 is calculated, to obtain the relative error sequence η mj of the model flow rate series Q j ,η j =(H cj -H tj ) / H tj , the subscript j represents the sequence number of the model flow rate Q m , the relative error η, the physical model test water depth H t and the numerical simulation water depth H c , as shown in Table 1: Figure 2

[0054] Step S5: under the condition of any given pier block fishway slope i and any given pier block column number N, the prototype pier block fishway is calculated by the computational fluid dynamics, wherein the pier block column number of the pier block fishway is 1, 3, 5 and 7, and the different prototype flow rates Q p Under the condition that the same given pier block fishway slope i=0.0% as in step S1 and the given pier block fishway pier block column number N=6, the different model flow rates Q p , wherein the prototype flow rate is λ pj times of the model flow rate sequence Q l 2.5 , that is, Q pj =λ l 2.5 Q mj ​In the numerical simulation, the water depth sequence corresponding to the front end of the middle pier of the first row of the prototype pier-block fishway is H pj ;

[0055] The computational method for the block-type fishway prototype was developed. The grid scheme and the computational fluid dynamics software Fluent were configured using grid scheme G2 with an overall grid layout ratio of 3 and a maximum grid size of 8 mm. The turbulence model was the standard k-ε turbulence model, with a velocity inlet condition at the inlet, a pressure outlet at the outlet boundary, a pressure inlet at the free water surface, and a wall function at the side walls. The governing equations were discretized using the finite volume method (FVM), a second-order central difference scheme for the diffusion term, the QUICK scheme for the convection term, the SIMPLEC algorithm for the coupling of pressure and velocity, and the volume of fluid (VOF) method. The computational model was simply replaced with the prototype block-type fishway; the other computational methods remained unchanged. Step S3 was a deterministic process, primarily focusing on the grid size and cloud computing technology. The grid size did not scale with the scale of the computational object, thus avoiding errors caused by scale-up. Cloud computing technology was introduced into the computational fluid dynamics calculations of the block-type fishway prototype, improving computational accuracy and reducing computational time.

[0056] After calculation, the prototype calculation results are output and processed by the computational fluid dynamics post-processing software CFD-Post to obtain different prototype flow rates Q p The water depth H at the front of the middle pier of the first row of the prototype pier-block fishway during numerical simulation under the following conditions: p ;

[0057] Step S6: Combine the model flow series Q mj The relative error sequence η j The water depth H at the front of the middle pier in the first row of the prototype pier-block fishway during numerical simulation is pj The water depth H at the front of the first row of middle pier blocks was measured on site. fj Correction, subscript f represents field measurement, according to the relative error between the physical model test and the model numerical simulation is the same as the relative error between the field measurement and the prototype numerical simulation, then η j =(H pj -H fj ) / H fj , that is (H cj -H tj ) / H tj =(H pj -H fj ) / H fj , find H fj =H pj ×H tj / H cj , the results are as followsFigure 3 As shown;

[0058] Step S7: Convert the prototype traffic sequence Q pj The water depth sequence H at the front end of the first row of the middle pier of the prototype pier-type fishway obtained by field measurement is corrected. fj and the corresponding contraction width w are imported into the data processing software of statistical products and service solutions; the final explicit expression Q=ν(w 2.5 )(g 0.5 )(H / w) μ By performing nonlinear fitting, we obtain the parameters ν and μ under the condition of the number of pier columns N, namely, when N=1, ν=0.55 and μ=1.62; when N=3, ν=0.37 and μ=1.58; when N=5, ν=0.34 and μ=1.57; when N=7, ν=0.29 and μ=1.55;

[0059] The specific fitting steps of the data processing software for statistical product and service solutions (SPSS) are as follows:

[0060] 1. First, import the data into the data processing software Statistical Products and Service Solutions Data Processing Software (SPSS);

[0061] 2. Then perform regression fitting, find the regression in the analysis, and then perform nonlinear fitting to determine the dependent variable and model expression;

[0062] 3. Save the pre-stored initial values ​​in the selection, check the residual value, and then you can get the reasonable specific values ​​of parameters α and β after fitting.

[0063] Then, the obtained number of pier blocks N and parameter value ν of different pier-block fishway were substituted into the graphic visualization and data analysis software Origin, and the pier-block fishway slope N was linearly fitted with the parameter ν, and A = 0.005, B = -0.084 and C = 0.628 were obtained; then, the obtained number of pier blocks N and parameter value μ of different pier-block fishway were substituted into the graphic visualization and data analysis software Origin, and the quadratic term fitting was performed on the pier block number N and parameter value μ of the pier-block fishway, and D = -0.012 and k5 = 1.631 were obtained, so ν = 0.005N 2 -0.084N+0.628, μ=-0.012N+1.631, the fitting results are as follows Figure 4 As shown ( Figure 4For the pier block fishway with slope i = 0.0% and different pier block column number N, the parameters v and mu are fitted by graphic visualization and data analysis software Origin, and it is noted that the effective range of the pier block fishway slope N is 1 ≤ N ≤ 7, and then the final expression of the pier block fishway flow is Q = (0.005N 2 -0.084N + 0.628) (w 2.5 )(g 0.5 )(H / w) (-0.012N+1.631) .

[0064] Then, assuming that the pier block fishway has pier block N = 4, the parameters v and mu under the condition of the slope are respectively 0.37 and 1.58, and then the real-time prediction formula of the pier block fishway flow is Q = 0.37 (B c 2.5 )(g 0.5 )(H / B c ) 1.58 , assuming that the water depth H of the first pier block of the pier block fishway is 0.20 m, and the corresponding fishway contraction width w is 0.64 m, then the fishway flow is 0.061 m 3 / s at this time.

[0065] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A method of predicting the flow rate of a fishway of different numbers of pier blocks, characterized by: The method comprises the following steps: Step S1: physical model test is performed on the pier block fishway model, and a pier block fishway physical model is established; Given the slope i of the pier block fishway remains unchanged, under the condition of any given number of pier block columns N, the physical model is measured under different model flow Q m The water depth at the front end of the first column of the pier block fishway in the physical model test is H t ; The physical model test adopts normal physical model, and comprehensively considers the requirements of the physical model water flow in the resistance square area, selects the linear scale λ l of the physical model γ , the angle scale λ v of the physical model l 0.5 , the flow rate scale λ Q of the physical model l 2.5 , and the roughness scale λ n of the physical model l 1 / 6 . Step S2: Dimensional analysis is performed on the established pier block fishway physical model to obtain the final explicit expression of the pier block fishway flow Q=ν(w 2.5 )(g 0.5 )(H / w) μ , where v and μ are constant coefficients, w is the contraction width, g is the gravitational acceleration, and H is the water depth at the front end of the middle pier block in the first row of the pier block fishway. Step S3: numerical simulation calculation is performed on the scaled pier block fishway in step S1, and the results are derived after calculation convergence, and the numerical simulation method and the corresponding optimal grid size during calculation are output; Post-processing is carried out by a computational fluid dynamics post-processing software, under the condition that the same slope i of the pier block fishway in step S1 is given, and the number N of pier block rows of the pier block fishway is given, the different model flow Q is calculated m Under the condition that the number N of pier block rows of the pier block fishway is given, the water depth H of the front end of the first middle pier block of the model pier block fishway in the numerical simulation is c ; Step S4: Calculate the relative error of the water depth H at the front of the first column of the middle pier of the numerical simulation of the pier block fishway in step S3 with the water depth H at the front of the first column of the middle pier of the physical model test in step S1, and obtain the relative error sequence η corresponding to the model flow series Q c . t The relative error of the water depth H at the front of the first column of the middle pier of the numerical simulation of the pier block fishway in step S3 with the water depth H at the front of the first column of the middle pier of the physical model test in step S1, and obtain the relative error sequence η corresponding to the model flow series Q mj . j , η j = (H cj -H tj ) / H tj , the sequence number j represents the sequence number corresponding to the model flow Q m , the relative error η, the physical model test water depth H t and the numerical simulation water depth H c . Step S5: under the condition of any given block fishway slope i and any given block column number N, the original prototype of the block fishway is calculated by computational fluid dynamics, and the different original prototype flow rates Q of the block fishway are output p Under the condition of any given block fishway slope i and any given block column number N, the original prototype of the block fishway is calculated by computational fluid dynamics, and the different original prototype flow rates Q of the block fishway are output p , wherein the original prototype flow rate Q p is a sequence of model flow rates Q pj , λ l 2.5 times, that is, Q pj = λ l 2.5 Q mj , the sequence of water depths corresponding to the front water depth of the middle block in the first column of the original prototype block fishway in the numerical simulation is H pj ; Step S6: Combine the model flow series Q mj The relative error series η j and the water depth series H corresponding to the water depth at the front of the first column of the middle pier of the prototype pier block fishway in the numerical simulation pj The water depth series H at the front of the first column of the middle pier of the prototype pier block fishway in the field measurement fj Correction, f represents field measurement, according to the relative error of physical model test and model numerical simulation, the relative error of field measurement and prototype numerical simulation is the same, then η j = (H pj -H fj ) / H fj , (H cj -H tj ) / H tj = (H pj -H fj ) / H fj , H fj =H pj ×H tj / H cj ; Step S7: The prototype flow sequence Q pj and the corresponding contraction width w of the first column of middle blocks of the prototype block fishway are imported into the data processing software of the statistical product and service solutions. fj and the corresponding contraction width w of the first column of middle blocks of the prototype block fishway are imported into the data processing software of the statistical product and service solutions. The final explicit expression of the flow rate of the pier block fishway in step S2 is Q=ν(w 2.5 )(g 0.5 ) (H / w) μ Nonlinear fitting is performed, and under the condition of a given pier block fishway slope i and an arbitrary pier block column number N, the expression of the flow rate of the pier block fishway is ν=AN 2 +BN+C, μ=DN+E, that is, Q=(AN 2 +BN+C)(w 2.5 )(g 0.5 ) (H / w) DN +E ; wherein A, B, C, D, and E are constant coefficients, the pier block column number N of the pier block fishway and the front water depth H of the middle pier block in the first column of the pier block fishway are obtained through field measurement, and the real-time flow rate in the fishway is obtained by substituting the expression.

2. The method of claim 1, wherein the number of pier blocks is different. The pier block fishway physical model is established in step S1, and the specific parameters are as follows: The geometric length of the pier-block fishway is L, the width is W, the pier blocks are square piers with a side length of s, the pier block height is h, the pier blocks are staggered, and the longitudinal distance is a x , the horizontal distance is a y The angle between the bottom surface of the block fishway and the horizontal plane is γ. The slope i of the block fishway is the tangent value of the angle γ between the bottom surface of the block fishway and the horizontal plane, that is, tanγ. N rows of blocks are arranged along the block fishway, N is an integer, and the distance between two blocks is w / 2.

3. The method of claim 2, wherein the number of the pier blocks is different. The established pier block fishway physical model is subjected to dimensional analysis in step S2, and the specific dimensional analysis is as follows: Flow Q is explicitly expressed by key parameters; Q=F(H, w, g), F is equation explicit expression, key parameters are the water depth H of the front end of the middle pier in the first row of pier block fishway, contraction width w and gravity acceleration g; the explicit expression of flow Q is rewritten into implicit expression, then F(Q, H, w, g)=0, wherein the total of 4 variables, flow Q is in unit of m³ / s, contraction width w is in unit of m, gravity acceleration g is in unit of m / s 2 , the water depth H of the front end of the middle pier in the first row of pier block fishway is in unit of m, time and length are set as basic variables, 4 variables are converted into 2 items through conversion, π is a hydraulics dimensional relationship item, π1=(w) a (g) b (Q), π2=(w) c (g) d (H), the units of key parameters are brought into π1 and π2 to ensure π1=1 and π2=1, π1 is time basic item, π2 is length basic item, calculation obtains a=-2.5, b=-0.5, c=-1, d=0, then π1=Q / (w 2.5 g 0.5 ), π2=H / w, time basic item π1 and length basic item π2 are combined, then Q / (w 2.5 g 0.5 )= ν(H / w) μ ; moving term obtains the final explicit expression of flow of pier block fishway.

4. The method of claim 3, wherein the number of the pier blocks is different. The numerical simulation calculation of the scaled pier block fishway and the determination of the optimal grid size in step S3 are as follows: S31: a numerical simulation geometric model of the scaled pier block fishway same as that in step S1 is established through a three-dimensional modeling software SolidWorks; S32: grid partitioning is performed by using numerical simulation grid partitioning software ANSYS ICEM, and the grid scheme is G k , the subscript k is a sequence number, and takes values of 1, 2, 3,..., and the grid overall layout ratio corresponding to the grid scheme is ξ k , ξ k is dimensionless, and the corresponding maximum grid size is δ k , δ k is in mm, and the corresponding total amount of generated grids is M k , M k is in ten-thousands, wherein the grid overall layout ratio ξ and the maximum grid size δ decrease with the increase of the sequence number k, and the total amount of grids M increases with the increase of the sequence number k, the whole grid type is a hexahedral structured grid without any local encryption, and is respectively exported as a calculation file with a suffix name of.mesh. S33: determine the numerical simulation optimal grid parameters, import the file with the suffix.mesh in step S32 into the fluid numerical simulation software Fluent for calculation, calculate the grid scheme G k and G k+1 respectively, both of which are set in the fluid numerical simulation software Fluent as follows: the turbulent flow model is the standard turbulent flow model Standard k-ε, the inlet adopts the velocity inlet condition, the outlet boundary adopts the pressure outlet, the free water surface adopts the pressure inlet, the side wall adopts the wall function, the discrete method of the control equation adopts the finite volume method FVM, the diffusion term adopts the second-order central difference format, the convection term adopts the QUICK format, the coupling of the pressure and the velocity adopts the SIMPLEC algorithm, and the calculation method adopts the fluid volume method VOF; then, data processing is performed through the numerical simulation post-processing software CFD-Post, the water depth H ck and H ck+1 in front of the first column of the middle block of the model block fishway is collected respectively, and the water depth H ck ≠ H ck+1 , return to step S32 to reduce the grid overall layout proportion and the maximum grid size, re-subdivide the grid to continue the calculation and data collection and comparison; when H ck = H ck+1 , output the grid overall layout proportion ξ k and the corresponding maximum grid size δ k of the optimal grid scheme G k .

5. The method of claim 1, wherein the number of the pier blocks is different. The determination of the constant coefficients A, B, C, D and E in step S7 is as follows: Step S71: The numerical simulation method in step S3 and the corresponding optimal grid size are used to perform computational fluid dynamics calculation on the prototype of the pier block fishway, wherein the number of pier block columns N is rounded, and the water depth H at the front end of the first column of the prototype pier block fishway is measured under different prototype flow rates Q p p ;​ Step S72: The water depth H at the front of the first column of the middle pier of the prototype pier block fishway is simulated by using step S6 p The correction is made, and the water depth sequence H at the front of the first column of the middle pier of the prototype pier block fishway is obtained by field measurement f ; Step S73: Corresponding to each pier block column number N, the prototype flow Q p and the measured water depth H at the front of the first pier block in the middle of the prototype pier block fishway f Substitute into the data processing software of statistical products and services solutions respectively, get the parameter v and the parameter μ under the condition of pier block column number N; Step S74: the parameters v and the parameters mu obtained under different pier block column numbers N in step S73 are respectively substituted into a data processing software, a quadratic term fitting is performed on the pier block column number N and the parameters v, the constant coefficient A, the constant coefficient B and the constant coefficient C are obtained, and a linear fitting is performed on the pier block column number N and the parameters mu, and the constant coefficient D and the constant coefficient E are obtained.

6. The method of claim 1, wherein the number of the pier blocks is different. In step S5, cloud computing technology is introduced in the computational fluid dynamics calculation of the pier block fishway prototype.

7. The method of claim 5, wherein the number of the pier blocks is different. In step S71, cloud computing technology is introduced in the computational fluid dynamics calculation of the pier block fishway prototype.

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