Numerical simulation method, device and medium for fluid state in water tunnel based on rough wall model

Abstract

This application discloses a method, apparatus, and medium for numerical simulation of fluid states in a water tunnel based on a rough wall model, relating to the field of numerical simulation technology. The method includes: acquiring a rough wall model corresponding to the working section of the water tunnel, as well as measuring the velocity field and pressure field of the fluid; predicting a first numerical range of the wall roughness of the rough wall model; adjusting the wall roughness based on the first numerical range to obtain the simulated pressure field of the fluid corresponding to each wall roughness; comparing the measured pressure field and the simulated pressure field, and obtaining the target simulated roughness corresponding to the CFD numerical simulation based on the comparison result, thereby completing the numerical simulation and correction of the fluid in the working section of the water tunnel. This application aims to solve the problem of poor accuracy in calculating the friction loss of water tunnels with rough walls in existing technologies, achieving rapid and accurate calculation of the friction loss of water tunnels with rough walls.

Description

Technical Field

[0001] This application relates to the field of numerical simulation technology, and in particular to a method, device and medium for numerical simulation of fluid state in a water tunnel based on a rough wall model. Background Technology

[0002] As a crucial device for hydrodynamic experimental research, the flow quality of the working section of a water tunnel is a vital factor in ensuring the accuracy of hydrodynamic experiments. However, along the flow direction of the water tunnel, the development of the boundary layer on the working section wall inevitably affects the flow velocity, resulting in pressure drop along the tunnel. For hydrodynamic experiments, especially those involving cavitation testing, the pressure drop along the working section of the water tunnel has a significant impact on the hydrodynamic measurement results.

[0003] Currently, research on friction loss in water tunnels mainly relies on experimental measurements and semi-empirical theoretical calculations (e.g., using the Colebrook-White formula to calculate the friction coefficient), or numerical simulations to calculate the friction resistance of flow on smooth walls. However, real water tunnels typically have rough walls, and using existing methods to calculate the friction resistance on rough walls yields inappropriate and inaccurate results. Summary of the Invention

[0004] To address the aforementioned problems and technical requirements, the applicant proposes a numerical simulation method, equipment, and medium for fluid states in a water tunnel based on a rough-walled model. This method aims to solve the problem of poor accuracy in calculating the friction resistance of a water tunnel with a rough wall in existing technologies, and to achieve rapid and accurate calculation of the friction resistance of a water tunnel with a rough wall.

[0005] This application provides a numerical simulation method for the fluid state in a water tunnel based on a rough wall model. The water tunnel includes a contracting section upstream and a working section in the middle of the water tunnel. The method includes: Obtain the rough wall model corresponding to the working section of the water tunnel, and obtain the measured velocity field and measured pressure field of the fluid obtained by conducting pressure drop measurement experiments in the working section of the water tunnel; Based on the measured velocity field and the measured pressure field, a first numerical range of the wall roughness of the roughness wall model is predicted; Based on the rough wall model, CFD numerical simulation of the fluid in the working section of the water tunnel is performed, and the wall roughness is adjusted based on the first numerical range to obtain the simulated pressure field of the fluid corresponding to each wall roughness. By comparing the measured pressure field and the simulated pressure field, the target simulated roughness corresponding to the CFD numerical simulation is obtained based on the comparison results, so as to complete the numerical simulation and correction of the fluid in the working section of the water tunnel.

[0006] According to the numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in the embodiments of this application, the measured velocity field includes the fluid velocity, and the measured pressure field includes the pressure drop along the flow path. Based on the measured velocity field and the measured pressure field, a first numerical range of the predicted wall roughness of the roughness wall model is included, comprising: The relationship between pressure drop along the flow path and flow velocity in the working section of the water tunnel at different flow velocities is determined, and a second numerical range of roughness height is determined based on the relationship. The first numerical range is obtained based on the second numerical range and the test pressure field.

[0007] According to the numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in the embodiments of this application, the corresponding relationship includes: the friction loss is proportional to the 1.75th power of the flow velocity, and the friction loss is proportional to the square of the flow velocity. When the relationship is that the friction drop is proportional to the 1.75th power of the flow velocity, the second numerical range of the roughness height is the interval from zero to the first preset value. When the relationship is that the friction drop is proportional to the square of the flow velocity, the second numerical range of the roughness height is an interval greater than or equal to the second preset value. The second preset value is greater than the first preset value.

[0008] According to the numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in this application, the first numerical range is obtained based on the second numerical range and the test pressure field, including: The friction drop along the friction line is input into a preset balance formula to obtain the wall friction velocity output by the balance formula. The equilibrium formula includes: , in, ; in, Indicates the wall friction speed. Represents the wall shear stress. Indicates fluid density, Indicates pressure drop along the process. This indicates the diameter of the working section of the water tunnel. Indicates the length of the working section of the water tunnel; The wall friction speed and the second value in the second numerical range are input into the roughness calculation formula to obtain the first value output by the roughness calculation formula, and the first numerical range is obtained. ; in, Indicates the second numerical range. Indicates the first numerical range. Indicates kinematic viscosity.

[0009] The numerical simulation method for fluid state inside a water tunnel based on a rough wall model, according to the embodiments of this application, after completing the numerical simulation of the fluid in the working section of the water tunnel, further includes: Based on the measured velocity field and the measured pressure field, the expansion angle range of the working section of the water tunnel is predicted; Based on the expansion angle range, the simulated expansion angle of the roughness wall model is adjusted, and the simulated pressure field after adjusting the simulated expansion angle is calculated; The target expansion angle is determined based on the pressure variation along the friction field in the adjusted simulated pressure field.

[0010] According to the numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in this application, the method predicts the expansion angle range of the working section of the water tunnel based on the measured velocity field and the measured pressure field, including: Based on the average flow velocity at the inlet section and the flow pressure in the flow core region, as well as the average flow velocity at the outlet section and the flow pressure in the flow core region, the expansion angle range of the working section of the water tunnel is predicted.

[0011] According to the numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in the embodiments of this application, before predicting the first numerical range of the wall roughness of the rough wall model, the method further includes: Obtain the assembly connection error requirements between the working section and the contraction section of the water tunnel; After predicting the first numerical range of wall roughness for the roughness wall model, the following is also included: The first numerical range is obtained by limiting the first numerical range based on the assembly connection error requirements.

[0012] According to the numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in this application, the target simulated roughness corresponding to the CFD numerical simulation is obtained based on the comparison results, including: Calculate the first slope of change of the measured pressure field and the second slope of change of the simulated pressure field; If the difference between the first and second slope changes is less than a preset value, the measured pressure field and the simulated pressure field are determined to be consistent, and the target simulated roughness is obtained.

[0013] This application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of the numerical simulation method for fluid state in a water tunnel based on a rough wall model as described above.

[0014] This application also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the numerical simulation method for fluid state in a water tunnel based on a rough wall model as described above.

[0015] The numerical simulation method, equipment, and medium for fluid states in a water tunnel based on a rough wall model provided in this application obtain a rough wall model corresponding to the working section of the water tunnel, and measure the velocity field and pressure field of the fluid obtained from pressure drop measurement experiments in the working section of the water tunnel. Based on the measured velocity field and measured pressure field, a first numerical range of wall roughness of the rough wall model is predicted. This application pre-estimates a wall roughness range based on the measurement data. Then, CFD numerical simulation is performed on the fluid in the working section of the water tunnel based on the rough wall model, and the wall roughness is adjusted based on the first numerical range to obtain the simulated pressure field of the fluid corresponding to each wall roughness, which greatly improves the simulation efficiency and realizes rapid and efficient reproduction of the flow state of the water tunnel model experiment. By comparing the measured pressure field and the simulated pressure field, the target simulated roughness corresponding to the CFD numerical simulation is obtained based on the comparison result, so as to quickly and accurately complete the numerical simulation and correction of the fluid in the working section of the water tunnel. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the numerical simulation method for fluid state inside a water tunnel based on a rough wall model provided in this application embodiment. Figure 2 This is a schematic diagram of the velocity distribution of the logarithmic law layer provided in an embodiment of this application; Figure 3 This is a comparison chart of the friction loss obtained by numerical simulation under a smooth wall surface and the friction loss obtained by experimental pressure measurement, provided in the embodiments of this application. Figure 4 This is a comparison chart of the friction loss obtained by numerical simulation under rough wall surface and the friction loss obtained by experimental pressure measurement, provided in the embodiments of this application. Figure 5 This is a schematic diagram simulating the pressure change of the fluid in the working section under different expansion angles provided in the embodiments of this application; Figure 6 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] This application provides a numerical simulation method for the fluid state within a water tunnel based on a rough wall model. The water tunnel includes a contracting section upstream and a working section midstream. This method can be applied to smart terminals and servers. This application uses the application of this method in a server as an example for illustration. Other descriptions in the embodiments are illustrative and not intended to limit the scope of protection of this application, and will not be elaborated further thereafter. The specific implementation of the method is as follows... Figure 1 As shown: Step 101: Obtain the rough wall model corresponding to the working section of the water tunnel, as well as the measured velocity field and measured pressure field of the fluid obtained from the pressure drop measurement experiment in the working section of the water tunnel.

[0020] Step 102: Based on the measured velocity field and measured pressure field, predict the first numerical range of the wall roughness of the roughness wall model.

[0021] Step 103: Perform CFD numerical simulation on the fluid in the working section of the water tunnel based on the rough wall model, and adjust the wall roughness based on the first numerical range to obtain the simulated pressure field of the fluid corresponding to each wall roughness.

[0022] Step 104: Compare the measured pressure field and the simulated pressure field, and obtain the target simulated roughness corresponding to the CFD numerical simulation based on the comparison results, so as to complete the numerical simulation and correction of the fluid in the working section of the water tunnel.

[0023] The numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in this application obtains a rough wall model corresponding to the working section of the water tunnel, and measures the velocity field and pressure field of the fluid obtained from pressure drop measurement experiments in the working section of the water tunnel. Based on the measured velocity field and measured pressure field, a first numerical range of wall roughness of the rough wall model is predicted. This application pre-estimates a wall roughness range based on the measurement data. Then, CFD numerical simulation of the fluid in the working section of the water tunnel is performed based on the rough wall model, and the wall roughness is adjusted based on the first numerical range to obtain the simulated pressure field of the fluid corresponding to each wall roughness. This greatly improves the simulation efficiency and enables rapid and efficient reproduction of the flow state of the water tunnel model experiment. By comparing the measured pressure field and the simulated pressure field, the target simulated roughness corresponding to the CFD numerical simulation is obtained based on the comparison result, so as to quickly and accurately complete the numerical simulation and correction of the fluid in the working section of the water tunnel.

[0024] In one specific embodiment, the flow in the working section of the water tunnel includes large-scale core region flow and small-scale boundary layer flow. The formation of pressure drop along the flow path is directly related to the development of the boundary layer on the water tunnel wall. Therefore, the simulation accuracy of the boundary layer flow is essential.

[0025] For this multi-scale problem, directly using the DNS method to solve the boundary layer flow would result in an excessive amount of numerical computation. In order to solve the above problem while taking into account both large-scale core region flow and small-scale boundary layer flow, this application uses the wall function method to solve the boundary layer flow.

[0026] The basic idea of ​​this application for solving water tunnel flow is: to use a turbulence model to solve the flow in the large-scale core region; and to use wall functions to correlate physical quantities with the solution variables of the turbulent core region for the boundary layer flow in the near-wall region where the Reynolds coefficient is low and the turbulence development is insufficient, thereby avoiding the difficulty of directly simulating the near-wall region.

[0027] Specifically, for smooth walls, dimensionless velocity is introduced. and dimensionless distance The velocity distribution of the boundary layer flow is described in equations (1) and (2): …………(1) …………(2) in, The time-averaged velocity at the measurement point (obtained under the combined action of the core region and the boundary layer) represents the average velocity at the measurement point. Indicates the wall friction speed. Represents the wall shear stress. Indicates the density of the fluid. This indicates the distance from the measurement point to the wall. Indicates dynamic viscosity. Indicates kinematic viscosity.

[0028] The boundary layer includes a viscous sublayer, a transition layer, and a logarithmic layer.

[0029] Among them, the boundary layer viscous sublayer ( The velocity is linearly distributed along the normal to the wall, as shown in formula (3): …………(3) Among them, the logarithmic law layer ( The velocity distribution along the wall normal is shown in formula (4): …………(4) in, Denotes the von Karman constant, and B represents the logarithmic law intercept constant, reflecting the characteristics of the transition zone between the viscous sublayer and the logarithmic law layer. For smooth walls, it is usually taken as von Karman constant. =0.41, B=5.2.

[0030] The transition layer is located between the viscous sublayer and the logarithmic law layer. Its viscous force is equivalent to the Reynolds shear stress, and its flow is relatively complex. Moreover, the thickness of the transition layer is very small. Its distribution can be smoothly transitioned from the viscous sublayer to the logarithmic law layer, or it can be classified into the logarithmic law layer.

[0031] In one specific embodiment, in actual engineering applications, the water tunnel walls are not smooth but possess a certain degree of roughness. The presence of wall roughness significantly increases turbulence near the wall, further leading to increased wall shear stress and disrupting the viscous sublayer. This will cause a downward shift in the velocity distribution of the logarithmic layer, as can be seen in [reference needed]. Figure 2 .

[0032] Here, "smooth wall" refers to a smooth wall surface, and "rough wall" refers to a rough wall surface.

[0033] For dimensionless velocities on rough walls Dimensionless distance The relationship changes accordingly, and the changed relationship is shown in formula (5): …………(5) in, This represents the damping function caused by roughness.

[0034] For rough walls of the sand grain type Represented as dimensionless roughness height The damping function.

[0035] in, .

[0036] in, and Take the same form, . in, Indicates the roughness height. This indicates the surface roughness.

[0037] Specifically, the flow types on rough walls and The parameter range includes: 1) Hydraulically smooth zone, Rough elements are submerged in a viscous sublayer, and the friction coefficient is only related to the Reynolds number.

[0038] 2) Transitional rough region, The viscous sublayer cannot completely cover the rough elements, and the friction resistance is related to both the Reynolds number and the roughness.

[0039] 3) Completely rough region, Rough elements penetrate the viscous sublayer, and the friction coefficient along the way is constant, depending only on the roughness; this is also known as the resistance square region.

[0040] In one specific embodiment, from a practical point of view, wall roughness is not the only factor affecting boundary layer flow; assembly and connection errors between the working section of the water tunnel and the upstream contraction section may also affect the boundary layer flow within the working section.

[0041] The first numerical range of the wall roughness is based on the wall roughness corresponding to the working section of the water tunnel and the assembly connection error requirements between the water tunnel contraction section and the working section of the water tunnel.

[0042] Specifically, based on the wall roughness and assembly connection error, the flow boundary layer and pressure drop along the friction are simulated and corrected under the accounting of the rough wall model.

[0043] At this point, the wall roughness no longer only characterizes the processing roughness of the working section wall of the water tunnel, but can be regarded as a generalized equivalent roughness parameter describing the boundary layer flow within the working section of the water tunnel.

[0044] Among them, for wall roughness The roughness ranges considerably, from the micrometer scale of the surface roughness of the working section of the water tunnel to the 10⁻¹ millimeter scale of the assembly error of the water tunnel segments. Therefore, it is necessary to study the roughness parameters. The range of values ​​is estimated to reduce the number of simulations and improve simulation efficiency.

[0045] In one specific embodiment, the velocity field being measured includes the flow velocity of the fluid, and the pressure field being measured includes pressure drop along the flow path.

[0046] Specifically, the concrete implementation of predicting the first numerical range of the wall roughness of the roughness wall model based on the measured velocity field and measured pressure field includes: The relationship between pressure drop along the flow path and flow velocity in the working section of the water tunnel at different flow velocities is determined, and a second numerical range of roughness height is determined based on the relationship; a first numerical range is obtained based on the second numerical range and the test pressure field.

[0047] In one specific embodiment, the corresponding relationships include: the friction loss is proportional to the 1.75th power of the flow velocity, and the friction loss is proportional to the square of the flow velocity.

[0048] Specifically, when the relationship is that the friction loss is proportional to the 1.75th power of the flow velocity, the second numerical range of the roughness height is the interval between zero and the first preset value; when the relationship is that the friction loss is proportional to the square of the flow velocity, the second numerical range of the roughness height is the interval greater than or equal to the second preset value.

[0049] The second preset value is greater than the first preset value.

[0050] In one specific embodiment, the specific implementation of obtaining the first numerical range based on the second numerical range and the test pressure field includes: Input the pressure drop along the friction path into the preset balance formula to obtain the wall friction velocity output by the balance formula.

[0051] The equilibrium formula is shown in formula (6): …………(6) in, .

[0052] in, Indicates the wall friction speed. Represents the wall shear stress. Indicates fluid density, Indicates pressure drop along the process. This indicates the diameter of the working section of the water tunnel. This indicates the length of the working section of the water tunnel.

[0053] Input the wall friction speed and the second value in the second numerical range into the roughness calculation formula to obtain the first value output by the roughness calculation formula, and obtain the first numerical range.

[0054] The roughness calculation formula is shown in formula (7): …………(7) in, Indicates the second numerical range. Indicates the first numerical range. Indicates kinematic viscosity.

[0055] For example, when the relationship is that the friction loss is proportional to the square of the flow velocity, the second numerical range of the roughness height is: By combining the pressure drop along the pressure field measured, formulas (6) and (7) are used to obtain... .

[0056] Specifically, in Within the range, adjust the wall roughness, when When the value is 0.2 mm, it matches the test results of pressure drop along the tunnel well, and reproduces the flow state in the working section of the water tunnel well.

[0057] The comparison between the pressure drop along the friction surface obtained from numerical simulation and the pressure drop results measured by experimental pressure under smooth and rough wall conditions can be found in [reference needed]. Figure 3 and Figure 4 .in, Figure 3 To compare the pressure drop along the friction surface obtained by numerical simulation under smooth wall conditions with the pressure drop results measured by experimental pressure; Figure 4 This is a comparison between the pressure drop along the friction surface obtained from numerical simulation under rough wall conditions and the pressure drop results measured by experimental pressure.

[0058] in, Figure 3 and Figure 4 The x-axis X (m) represents the fluid flow distance, and the y-axis... It indicates pressure.

[0059] pass Figure 3 and Figure 4 It can be seen that whether or not rough wall correction is performed, there is a significant difference in the friction loss rate of the flow in the working section of the water tunnel. This is because this application achieves the accuracy of the fluid simulation of the working section of the water tunnel by accurately and quickly simulating the fluid state of the water tunnel by adjusting the wall roughness.

[0060] In one specific embodiment, to eliminate the pressure drop along the working section of the water tunnel, the working section can be given a certain expansion angle. The range of the expansion angle of the working section can be estimated based on the measurement results of the water tunnel test. Specifically, the range of the expansion angle of the working section is predicted based on the measured velocity field and pressure field; based on the expansion angle range, the simulated expansion angle of the roughness wall model is adjusted, and the simulated pressure field after the adjustment of the simulated expansion angle is calculated; the target expansion angle is determined based on the pressure change along the working section in the adjusted simulated pressure field.

[0061] Specifically, the working section of the water tunnel is selected as the control volume. Based on the incompressible fluid continuity equation, it is assumed that the flow rates at the inlet and outlet sections of the working section are equal, as shown in formula (8): …………(8) in, Indicates volumetric flow rate, Indicates the cross-sectional area of ​​the inlet. Indicates the cross-sectional area of ​​the outlet. This represents the average flow velocity at the inlet cross-section. This represents the average flow velocity at the outlet section.

[0062] Furthermore, based on the incompressible Bernoulli equation, formula (9) is obtained: ...(9) in, This represents the flow pressure in the flow core region at the inlet section. This indicates the flow pressure in the flow core region at the outlet section.

[0063] Specifically, ignoring the boundary layer thickness at the inlet of the working section, the effective flow surface at the inlet of the working section is... Boundary layer development causes changes in pressure drop along the tunnel. The theoretical value of the boundary layer thickness in the working section of the water tunnel is... Based on theoretical values, the effective flow surface of the flow core region is approximately: Correspondingly, the effective flow surface at the outlet of the working section is approximately: The boundary layer thickness at the exit section can be obtained by solving the simultaneous equations. For example, the boundary layer thickness at the exit section is... =5.4mm.

[0064] To counteract the influence of the boundary layer on the core flow region of the working section, the expansion angle of the working section is calculated, as shown in formula (10): …………(10) in, Represents the expansion angle, for example, based on =5.4mm, thus obtaining the expansion angle. .

[0065] The expansion angle is derived through simplified theory, and then a CFD numerical simulation correction method based on a rough wall model is used to simulate the pressure changes of the fluid in the working section under different expansion angles. Figure 5 As shown.

[0066] pass Figure 5 It can be obtained that, with the expansion angle of the working section of the water tunnel... With the increase of [value], the change in flow friction pressure changes from an approximately linear decrease to a linear increase. Keeping the friction pressure constant, the expansion angle can [be adjusted / adjusted]. The values ​​are taken within a certain range. Furthermore, the numerical simulation results and theoretical estimates show good agreement.

[0067] In one specific embodiment, the specific implementation of obtaining the target simulated roughness corresponding to the CFD numerical simulation based on the comparison results includes: Calculate the first slope of the measured pressure field and the second slope of the simulated pressure field; if the difference between the first slope and the second slope is less than a preset value, determine that the measured pressure field and the simulated pressure field are consistent, and obtain the target simulated roughness under this condition.

[0068] The following is an illustration using a specific example: (1) Establish a CFD numerical calculation model of the water tunnel, control its boundary layer mesh scale, and ensure that the dimensionless distance of the working section of the water tunnel is within the corresponding simulated flow velocity. The values ​​range from 30 to 300. Numerical simulation studies of the flow in the working section are conducted based on the Reynolds-averaged Navier-Stokes equations, turbulence models, and wall function methods. The boundary parameters of the numerical calculation model are set with reference to the flow velocity in the working section and the measured pressure downstream of the working section in the water tunnel test.

[0069] (2) Based on the test pressure difference measurement results, complete the assessment of the wall surface roughness. The estimated range of values.

[0070] Firstly, consider the pressure drop along the flow path at different flow velocities during the water tunnel experiment. With flow rate The relationship is used to determine the flow type within the working section of the water tunnel, such as This is a hydraulically smooth region. This is the fully rough region, and the dimensionless roughness height is determined accordingly. The range of values ​​for is then determined. Further calculations using force balance formulas are then performed to determine the wall shear stress of the water tunnel working section. Wall friction speed The wall roughness is obtained. The range of values ​​for .

[0071] (3) Based on Parameter prediction range, wall roughness measurement The adjustment is then made, and by comparing the numerical simulation of pressure drop along the flow path with the experimental measurement results, a suitable CFD numerical simulation wall roughness is obtained, thereby completing the numerical simulation correction of the flow in the working section of the water tunnel.

[0072] (4) For the modified CFD numerical calculation model of the water tunnel, the geometric dimensions of the working section of the water tunnel are further slightly modified to give it a certain expansion angle (the dimensions of the downstream segment connected to the working section of the water tunnel are also adjusted accordingly). When meshing the working section, the height of the bottom mesh remains unchanged; then, the flow under different expansion angle conditions is numerically simulated. By comparing the changes in friction pressure in the working section under different expansion angles, the expansion angle parameters corresponding to the working section are obtained with the friction pressure approximately kept constant, thus completing the optimization design of the working section of the water tunnel.

[0073] This application can accurately reproduce the flow state of water tunnel model tests, greatly improving the accuracy of the comparison between water tunnel tests and numerical simulations.

[0074] Based on the numerical simulation correction of the pressure drop along the tunnel, it can also be applied to the optimization design of the tunnel, and to the parameter calculation and prediction of the expansion angle of the working section of the tunnel, so as to eliminate the adverse effects of the pressure drop along the tunnel.

[0075] Figure 6 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 6 As shown, the electronic device may include a processor 601, a communication interface 602, a memory 603, and a communication bus 604. The processor 601, communication interface 602, and memory 603 communicate with each other via the communication bus 604. The processor 601 can call logical instructions from the memory 603 to execute a numerical simulation method for the fluid state inside a water tunnel based on a rough wall model.

[0076] Furthermore, the logical instructions in the aforementioned memory 603 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0077] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, and when the program instructions are executed by a computer, the computer is able to execute the numerical simulation method of fluid state in a water tunnel based on a rough wall model provided by the above methods.

[0078] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the numerical simulation method for fluid state in a water tunnel based on a rough wall model provided in the above embodiments.

[0079] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0080] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0081] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A numerical simulation method for fluid state inside a water tunnel based on a rough wall model, characterized in that, The water tunnel includes: a contraction section upstream of the water tunnel and a working section in the middle of the water tunnel, and the method includes: Obtain the rough wall model corresponding to the working section of the water tunnel, and obtain the measured velocity field and measured pressure field of the fluid obtained by conducting pressure drop measurement experiments in the working section of the water tunnel; Based on the measured velocity field and the measured pressure field, a first numerical range of the wall roughness of the roughness wall model is predicted; Based on the rough wall model, CFD numerical simulation of the fluid in the working section of the water tunnel is performed, and the wall roughness is adjusted based on the first numerical range to obtain the simulated pressure field of the fluid corresponding to each wall roughness. By comparing the measured pressure field and the simulated pressure field, the target simulated roughness corresponding to the CFD numerical simulation is obtained based on the comparison results, so as to complete the numerical simulation and correction of the fluid in the working section of the water tunnel.

2. The numerical simulation method for fluid state in a water tunnel based on a rough wall model according to claim 1, characterized in that, The measured velocity field includes the fluid velocity, and the measured pressure field includes the pressure drop along the friction surface. Based on the measured velocity field and the measured pressure field, a first numerical range of the predicted wall roughness of the roughness wall model is included, comprising: The relationship between pressure drop along the flow path and flow velocity in the working section of the water tunnel at different flow velocities is determined, and a second numerical range of roughness height is determined based on the relationship. The first numerical range is obtained based on the second numerical range and the test pressure field.

3. The numerical simulation method for fluid state inside a water tunnel based on a rough wall model according to claim 2, characterized in that, The corresponding relationships include: the friction loss is directly proportional to the 1.75th power of the flow velocity, and the friction loss is directly proportional to the square of the flow velocity; When the relationship is that the friction drop is proportional to the 1.75th power of the flow velocity, the second numerical range of the roughness height is the interval from zero to the first preset value. When the relationship is that the friction drop is proportional to the square of the flow velocity, the second numerical range of the roughness height is an interval greater than or equal to the second preset value. The second preset value is greater than the first preset value.

4. The numerical simulation method for fluid state in a water tunnel based on a rough wall model according to claim 3, characterized in that, Based on the second numerical range and the test pressure field, the first numerical range is obtained, including: The friction drop along the friction line is input into a preset balance formula to obtain the wall friction velocity output by the balance formula. The equilibrium formula includes: ， in, ; in, Indicates the wall friction speed. Represents the wall shear stress. Indicates fluid density, Indicates pressure drop along the process. This indicates the diameter of the working section of the water tunnel. Indicates the length of the working section of the water tunnel; The wall friction speed and the second value in the second numerical range are input into the roughness calculation formula to obtain the first value output by the roughness calculation formula, and the first numerical range is obtained. ； in, Indicates the second numerical range. Indicates the first numerical range. Indicates kinematic viscosity.

5. The numerical simulation method for fluid state in a water tunnel based on a rough wall model according to any one of claims 1-4, characterized in that, After completing the numerical simulation of the fluid in the working section of the water tunnel, the following steps are also included: Based on the measured velocity field and the measured pressure field, the expansion angle range of the working section of the water tunnel is predicted; Based on the expansion angle range, the simulated expansion angle of the roughness wall model is adjusted, and the simulated pressure field after adjusting the simulated expansion angle is calculated; The target expansion angle is determined based on the pressure variation along the friction field in the adjusted simulated pressure field.

6. The numerical simulation method for fluid state in a water tunnel based on a rough wall model according to claim 5, characterized in that, Based on the measured velocity field and the measured pressure field, the expansion angle range of the working section of the water tunnel is predicted, including: Based on the average flow velocity at the inlet section and the flow pressure in the flow core region, as well as the average flow velocity at the outlet section and the flow pressure in the flow core region, the expansion angle range of the working section of the water tunnel is predicted.

7. The numerical simulation method for fluid state in a water tunnel based on a rough wall model according to any one of claims 1-4, characterized in that, Before predicting the first numerical range of wall roughness for the roughness wall model, the following steps are also included: Obtain the assembly connection error requirements between the working section and the contraction section of the water tunnel; After predicting the first numerical range of wall roughness for the roughness wall model, the following is also included: The first numerical range is obtained by limiting the first numerical range based on the assembly connection error requirements.

8. The numerical simulation method for fluid state in a water tunnel based on a rough wall model according to any one of claims 1-4, characterized in that, Based on the comparison results, the target simulated roughness corresponding to the CFD numerical simulation is obtained, including: Calculate the first slope of change of the measured pressure field and the second slope of change of the simulated pressure field; If the difference between the first and second slope changes is less than a preset value, the measured pressure field and the simulated pressure field are determined to be consistent, and the target simulated roughness is obtained.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the numerical simulation method for fluid state in a water tunnel based on a rough wall model as described in any one of claims 1 to 8.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the numerical simulation method for fluid state in a water tunnel based on a rough wall model as described in any one of claims 1 to 8.

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