High-speed train special airfoil optimization design method and system

Abstract

The application discloses a high-speed train special airfoil optimization design method and system, establishes a high-speed train simulation model, selects a basic high-lift laminar airfoil, calculates a lift coefficient and a drag coefficient, obtains an optimization initial value of the basic high-lift laminar airfoil, obtains a distance range between an upper wall surface of the high-speed train and the basic high-lift laminar airfoil and an installable range of the basic high-lift laminar airfoil based on high-speed railway limit conditions, determines a number of function types based on optimization experience, selects a Hicks-Henne disturbance function to disturb a maximum disturbance position of the basic high-lift laminar airfoil, obtains the airfoil after disturbance, generates an airfoil aerodynamic force calculation grid, obtains a lift coefficient and a drag coefficient of the airfoil after disturbance, establishes a simulation optimization design platform, obtains a parameter optimal value, and completes optimization design of the high-speed train special airfoil. The application improves the lift coefficient of the airfoil under a design working condition, and provides an important basis for research and development of a aerodynamic cooperative lift train.

Description

Technical Field

[0001] This application belongs to the field of high-speed railway transportation engineering application technology, specifically involving a method and system for optimizing the design of airfoils for high-speed trains. Background Technology

[0002] As train operating speeds increase, a series of new problems inevitably arise. From an economic perspective alone, the significant increase in drag and accelerated wheel wear in wheel-rail trains will greatly increase operating costs. These are issues that China urgently needs to address in developing its next-generation trains. To reduce the life-cycle cost of trains at higher speeds, researchers have proposed the concept of aerodynamic lift-coordinated high-speed trains. This concept breaks through the traditional aerodynamic design philosophy of high-speed trains, combining the advantages of both high-speed trains and aircraft. The aim is to increase the aerodynamic lift of the train to achieve overall energy conservation and emission reduction.

[0003] The so-called aerodynamic lift-coordinated train refers to a high-speed train with an additional set of wings added to its roof to increase lift, reduce weight, decrease wheel wear, further improve the lift-to-drag ratio, and reduce running drag. Therefore, optimizing the design of dedicated airfoils for high-speed trains is an important task in the development of aerodynamic lift-coordinated trains. Currently, directly applying airfoils to high-speed trains still faces a series of problems. The biggest difference between the design of dedicated airfoils for high-speed trains and traditional airfoil design is the need to consider the influence of the high-speed train itself on the aerodynamic forces of the airfoil, i.e., the wall effect. Systematic research on this topic is still lacking both domestically and internationally. Summary of the Invention

[0004] This application proposes an optimized design method and system for airfoils specifically designed for high-speed trains, which significantly improves the lift coefficient of the airfoil and reduces the adverse effects of wall effects on high-speed trains.

[0005] To achieve the above objectives, this application provides the following solution:

[0006] An optimized design method for airfoils specifically designed for high-speed trains.

[0007] A high-speed train simulation model is established, and a basic high-lift laminar flow airfoil is selected based on the high-speed train simulation model.

[0008] Based on the aforementioned high-lift laminar airfoil, the lift coefficient and drag coefficient are calculated.

[0009] Based on the lift coefficient and the drag coefficient, the optimized initial values ​​of the basic high-lift laminar airfoil are obtained;

[0010] Based on the clearance conditions of high-speed railways, the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, and the installation range of the basic high-lift laminar flow airfoil are obtained.

[0011] Based on optimization experience, the number of deterministic functions is determined, and the position of maximum disturbance of the Hicks-Henne perturbation function for the basic high-lift laminar airfoil is selected.

[0012] Based on the optimized initial values ​​of the basic high-lift laminar airfoil and the maximum disturbance position, the disturbed airfoil is obtained, the airfoil aerodynamic calculation grid is generated, and the lift coefficient and drag coefficient of the disturbed airfoil are obtained.

[0013] A simulation optimization design platform is established to obtain the optimal parameter values ​​based on the disturbed airfoil, the aerodynamic calculation grid of the airfoil, the lift coefficient and drag coefficient of the disturbed airfoil, and the optimization algorithm.

[0014] Based on the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, the installation range of the basic high-lift laminar flow airfoil, and the optimal value of the parameters, the optimized design of the airfoil for high-speed trains is completed.

[0015] Preferably, the high-speed train simulation model is simplified into a three-car train, namely the lead car, the carriages, and the tail car, with the basic high-lift laminar flow airfoil placed in the middle of the carriages.

[0016] Preferably, the Hicks-Henne perturbation function is Where C ck To optimize parameters, f k (x) is the selected type function;

[0017] The maximum disturbance locations are at 25%, 30%, 70%, and 75% of the chord length.

[0018] Preferably, the basic high-lift laminar airfoil parameterization program is written using MATLAB to obtain the perturbed airfoil.

[0019] Preferably, pointwise software is used to write a script file to generate the airfoil aerodynamic calculation grid.

[0020] Preferably, Fluent software is used to write a script file that sets the calculation conditions to obtain the airfoil's lift coefficient and drag coefficient after disturbance.

[0021] Preferably, the simulation optimization design platform is established using the iSight software and connected to the MATLAB software. Based on the perturbed airfoil, the aerodynamic calculation grid of the airfoil, and the lift coefficient and drag coefficient of the perturbed airfoil, optimization variables and constraints are set.

[0022] Based on the optimization variables and constraints, the optimal values ​​of the parameters are obtained using the Kriging surrogate model and genetic algorithm.

[0023] An optimized design system for airfoils specifically designed for high-speed trains.

[0024] It includes a model building module, a calculation module, an optimization initial value acquisition module, an installation range acquisition module, a disturbance location acquisition module, an optimization module, an optimal parameter acquisition module, and an airfoil design module;

[0025] The model building module establishes a high-speed train simulation model and selects a basic high-lift laminar airfoil based on the high-speed train simulation model.

[0026] The calculation module is used to calculate the lift coefficient and drag coefficient based on the basic high-lift laminar airfoil;

[0027] The initial optimization value acquisition module is used to obtain the initial optimization value of the basic high-lift laminar airfoil based on the lift coefficient and the drag coefficient.

[0028] The installation range acquisition module is used to obtain the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, and the installation range of the basic high-lift laminar flow airfoil, based on the high-speed railway clearance conditions.

[0029] The disturbance location acquisition module is used to determine the number of functions based on optimization experience and select the maximum disturbance location of the Hicks-Henne disturbance function for the basic high-lift laminar airfoil.

[0030] The optimization module is used to obtain the perturbed airfoil based on the initial optimization values ​​of the basic high-lift laminar airfoil and the maximum perturbation position, generate an airfoil aerodynamic calculation grid, and obtain the lift coefficient and drag coefficient of the perturbed airfoil.

[0031] The optimal parameter acquisition module is used to establish a simulation optimization design platform to obtain the optimal parameter values ​​based on the disturbed airfoil, the airfoil aerodynamic calculation grid, the disturbed airfoil lift coefficient and drag coefficient, and the optimization algorithm.

[0032] The airfoil design module is used to optimize the design of a dedicated airfoil for high-speed trains based on the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, the installation range of the basic high-lift laminar flow airfoil, and the optimal value of the parameters.

[0033] The beneficial effects of this application are as follows: Compared with the prior art, this application systematically studies how to overcome the adverse effects caused by the wall effect faced by high-speed trains, designs and optimizes the airfoil specifically for high-speed trains, significantly improves the lift coefficient of the airfoil under design conditions, effectively reduces the weight of the train, reduces wheel wear, and lowers the train's running resistance, providing an important foundation for the research and development of aerodynamically coordinated lift trains. This application has broad application potential and practical value. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of this application, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart of the high-speed train-specific airfoil optimization design method according to Embodiment 1 of this application;

[0036] Figure 2 This refers to the clearance constraint conditions for high-speed trains in this embodiment.

[0037] Figure 3 This is a schematic diagram of the numerical calculation model in Embodiment 1.

[0038] Figure 4 The Hicks-Henne type function selected in this embodiment;

[0039] Figure 5 This is a schematic diagram of the basic and optimized airfoils in this embodiment.

[0040] Figure 6 This is a comparison chart of the lift coefficients of the airfoil before and after optimization in Embodiment 1.

[0041] Figure 7 This is a comparison chart of the lift-to-drag ratio of the airfoil before and after optimization in this embodiment. Detailed Implementation

[0042] 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, and 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 application.

[0043] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1:

[0045] like Figures 1 to 5 As shown, a method for optimizing the design of airfoils for high-speed trains specifically includes the following steps:

[0046] Step (1): Establish a high-speed train simulation model, select a basic high-lift laminar flow airfoil, calculate the airfoil lift coefficient and drag coefficient, and determine the initial optimization values.

[0047] Step (2): Set the angle of attack A of the basic high-lift airfoil to 10°, where A refers to the airfoil rotating 10° clockwise around its trailing edge. The trailing edge of the basic high-lift laminar airfoil is 0.3m from the upper wall of the high-speed train; the chord length of the basic high-lift laminar airfoil is 0.6m. The operating speed of the basic high-lift laminar airfoil is 0.367Ma. The high-speed train model is simplified to a three-car train: the lead car, the carriages, and the tail car, with the basic high-lift laminar airfoil placed in the middle of the carriages. The total length of the train is 76m. Fluent calculations are performed using the SST k-omega turbulence model, with pressure far-field boundary conditions set and an incoming flow velocity of 125m / s.

[0048] Step (3): After trial and error, four optimization parameters were determined, and the Hicks-Henne perturbation function method was selected as the airfoil parameterization method to determine the location of the maximum perturbation. The maximum perturbation locations are at 25%, 30%, 70%, and 75% of the chord length. The Hicks-Henne perturbation function is as follows: Where C ck To optimize parameters, f k (x) is the selected type function.

[0049] Hicks-Henne airfoil parameterization method:

[0050] The shapes of the upper and lower surfaces of the airfoil are determined by the curvature function y c and thickness function y t To indicate:

[0051] y u =y c +y t

[0052] y l =y c -y t

[0053] Where y u The y-coordinate represents the vertical coordinate of the upper surface of the airfoil. l This represents the ordinate of the lower surface of the airfoil.

[0054] y c and y t It can be defined as follows:

[0055]

[0056]

[0057] In the formula y c (x) and y t (x) represents the thickness and camber function of the reference airfoil. N / 2 represents the number of camber and thickness control parameters selected, and c ck and c tk For the corresponding design variables, f k (x) represents the selected type function. The classic Hicks-Henne type function is chosen, i.e.:

[0058] f k (x)=sin 4 (πx e(k) )

[0059] in Take x k Each is a given value;

[0060] Based on the relevant optimization experience accumulated before formal optimization, four optimization design variables are selected as follows: c c1 c c2 c t1 c t2 The corresponding x k Let's take the values: x1 = 0.3, x2 = 0.7, x3 = 0.25, x4 = 0.75(x k (This determines the location of maximum effect of the perturbation function).

[0061] Step (4): Use MATLAB to write a basic high-lift laminar flow airfoil parameterization program to output the perturbed airfoil.

[0062] Step (5): Write the script file for generating the mesh in the Pointwise software to obtain the airfoil aerodynamic calculation mesh.

[0063] Step (6): Write a script file in Fluent software to set the calculation conditions, which will be used to automatically calculate the lift coefficient and drag coefficient of the airfoil after disturbance, such as... Figure 6 , Figure 7 As shown.

[0064] Step (7): Establish a simulation optimization design platform in iSight. Based on the perturbed airfoil, the perturbed airfoil lift coefficient and drag coefficient, and the airfoil aerodynamic calculation grid, set optimization variables and constraints, select the Kriging surrogate model and genetic algorithm, and obtain the optimal values ​​of design parameters.

[0065] Step (8): Based on the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, the installation range of the basic high-lift laminar flow airfoil, and the optimal parameter values, the optimized design of the high-speed train special airfoil is completed.

[0066] Example 2:

[0067] An optimization design system for a high-speed train-specific airfoil includes a model building module, a calculation module, an optimization initial value acquisition module, an installation range acquisition module, a disturbance location acquisition module, an optimization module, an optimal parameter acquisition module, and an airfoil design module.

[0068] The model building module establishes a high-speed train simulation model and selects a basic high-lift laminar airfoil based on the high-speed train simulation model.

[0069] The calculation module is used to calculate the lift coefficient and drag coefficient based on a basic high-lift laminar airfoil;

[0070] The initial value acquisition module is used to obtain the initial optimization values ​​of the basic high-lift laminar airfoil based on the lift coefficient and the drag coefficient.

[0071] The installation range acquisition module is used to obtain the distance range between the upper wall of the high-speed train and the foundation high-lift laminar flow airfoil, and the installation range of the foundation high-lift laminar flow airfoil, based on the high-speed railway clearance conditions.

[0072] The disturbance location acquisition module is used to determine the number of functions based on optimization experience and select the maximum disturbance location of the Hicks-Henne disturbance function for the basic high-lift laminar airfoil.

[0073] The optimization module is used to obtain the perturbed airfoil based on the initial optimization values ​​and the maximum perturbation position of the basic high-lift laminar airfoil, generate the airfoil aerodynamic calculation grid, and obtain the lift coefficient and drag coefficient of the perturbed airfoil.

[0074] The optimal parameter acquisition module is used to establish a simulation optimization design platform, and obtains the optimal parameter values ​​based on the perturbed airfoil, the airfoil aerodynamic calculation grid, the perturbed airfoil lift coefficient and drag coefficient, and the optimization algorithm.

[0075] The airfoil design module is used to optimize the design of a dedicated airfoil for high-speed trains based on the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, the installation range of the basic high-lift laminar flow airfoil, and the optimal parameter values.

[0076] The embodiments described above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Any modifications and improvements made to the technical solutions of this application by those skilled in the art without departing from the spirit of this application shall fall within the protection scope defined by the claims of this application.

Claims

1. An optimized design method for a high-speed train-specific airfoil, characterized in that, Step 1: Establish a high-speed train simulation model. Based on the high-speed train simulation model, select a basic high-lift laminar airfoil and set the angle of attack A of the basic high-lift airfoil to 10°. The angle of attack A refers to the airfoil rotating 10° clockwise around the trailing edge point. The distance between the trailing edge point of the basic high-lift laminar airfoil and the upper wall of the high-speed train is 0.3m. The chord length of the basic high-lift laminar airfoil is 0.6m. The operating speed of the basic high-lift laminar airfoil is 0.367Ma. The high-speed train model is simplified to a three-car train, namely the head car, the carriages, and the tail car. The basic high-lift laminar airfoil is placed in the middle of the carriages. The total length of the train is 76m. The incoming flow velocity is 125m / s. The turbulence model is the SST k-omega model. Set the pressure far-field boundary conditions. Step 2: Based on the aforementioned high-lift laminar airfoil, calculate the lift coefficient and drag coefficient; Step 3: Based on the lift coefficient and the drag coefficient, obtain the optimized initial values ​​for the basic high-lift laminar airfoil; Step 4: Based on the high-speed railway clearance conditions, obtain the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, and the installation range of the basic high-lift laminar flow airfoil; Step 5: Based on optimization experience, determine the number of perturbation functions, select the Hicks-Henne perturbation function, determine the maximum perturbation location of the basic high-lift laminar airfoil, determine four optimization parameters, select the Hicks-Henne perturbation function method as the airfoil parameterization method, and determine the maximum perturbation location, which is at 25%, 30%, 70%, and 75% of the chord length. The Hicks-Henne perturbation function is as follows: ,in To optimize parameters, For the selected type function; Hicks-Henne airfoil parameterization method: The shapes of the upper and lower surfaces of the airfoil are determined by the curvature function. and thickness function To indicate: in This represents the ordinate of the upper surface of the airfoil. The vertical coordinate represents the lower surface of the airfoil; and Defined as follows: In the formula and N represents the thickness and camber functions of the reference airfoil; N / 2 represents the number of camber and thickness control parameters selected. and For the corresponding design variables, For the selected Hicks-Henne type function, i.e.: in ,Pick Each is a given value; The four optimization design variables are as follows: , , , Correspondingly Take them separately: =0.3, =0.7, =0.25, =0.75, This determines the location of maximum effect of the perturbation function; Step 6: Based on the optimized initial values ​​of the basic high-lift laminar airfoil and the maximum disturbance position, obtain the disturbed airfoil, generate the airfoil aerodynamic calculation grid, and obtain the lift coefficient and drag coefficient of the disturbed airfoil; Step 7: Using the iSight software, establish a simulation optimization design platform, connect it to the MATLAB software, and set optimization variables and constraints based on the perturbed airfoil, the aerodynamic calculation grid of the airfoil, and the lift and drag coefficients of the perturbed airfoil. Based on the optimization variables and constraints, use the Kriging surrogate model and genetic algorithm to obtain the optimal parameter values. Step 8: Based on the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, the installation range of the basic high-lift laminar flow airfoil, and the optimal value of the parameters, complete the optimized design of the airfoil for high-speed trains.

2. The optimized design method for high-speed train-specific airfoils according to claim 1, characterized in that, The basic high-lift laminar flow airfoil parameterization program was written using MATLAB to obtain the perturbed airfoil.

3. The optimized design method for high-speed train-specific airfoils according to claim 1, characterized in that, Using the Pointwise software, a script file was written to generate the aerodynamic calculation mesh for the airfoil.

4. The optimized design method for high-speed train-specific airfoils according to claim 1, characterized in that, Using Fluent software, a script file was written to set the calculation conditions, and the lift coefficient and drag coefficient of the perturbed airfoil were obtained.

5. An optimized design system for a high-speed train-specific airfoil, characterized in that, It includes a model building module, a calculation module, an optimization initial value acquisition module, an installation range acquisition module, a disturbance location acquisition module, an optimization module, an optimal parameter acquisition module, and an airfoil design module; The model building module establishes a high-speed train simulation model. Based on the high-speed train simulation model, a basic high-lift laminar airfoil is selected, and the angle of attack A of the basic high-lift airfoil is set to 10°. The angle of attack A refers to the airfoil rotating 10° clockwise around the trailing edge point. The distance between the trailing edge point of the basic high-lift laminar airfoil and the upper wall of the high-speed train is 0.3m. The chord length of the basic high-lift laminar airfoil is 0.6m. The operating speed of the basic high-lift laminar airfoil is 0.367Ma. The high-speed train model is simplified to a three-car train, namely the head car, the carriages, and the tail car. The basic high-lift laminar airfoil is placed in the middle of the carriages. The total length of the train is 76m. The incoming flow velocity is 125m / s. The turbulence model is the SST k-omega model, and pressure far-field boundary conditions are set. The calculation module is used to calculate the lift coefficient and drag coefficient based on the basic high-lift laminar airfoil; The initial optimization value acquisition module is used to obtain the initial optimization value of the basic high-lift laminar airfoil based on the lift coefficient and the drag coefficient. The installation range acquisition module is used to obtain the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, and the installation range of the basic high-lift laminar flow airfoil, based on the high-speed railway clearance conditions. The disturbance location acquisition module is used to determine the number of perturbation functions based on optimization experience, select the Hicks-Henne perturbation function for the maximum disturbance location of the basic high-lift laminar airfoil, determine four optimization parameters, select the Hicks-Henne perturbation function method as the airfoil parameterization method, and determine the maximum disturbance location. The maximum disturbance location is at 25%, 30%, 70%, and 75% of the chord length, where the Hicks-Henne perturbation function is: ,in To optimize parameters, For the selected type function; Hicks-Henne airfoil parameterization method: The shapes of the upper and lower surfaces of the airfoil are determined by the curvature function. and thickness function To indicate: in This represents the ordinate of the upper surface of the airfoil. The vertical coordinate represents the lower surface of the airfoil; and Defined as follows: In the formula and N represents the thickness and camber functions of the reference airfoil; N / 2 represents the number of camber and thickness control parameters selected. and For the corresponding design variables, For the selected Hicks-Henne type function, i.e.: in ,Pick Each is a given value; The four optimization design variables are as follows: , , , Correspondingly Take them separately: =0.3, =0.7, =0.25, =0.75, This determines the location of maximum effect of the perturbation function; The optimization module is used to obtain the perturbed airfoil based on the initial optimization values ​​of the basic high-lift laminar airfoil and the maximum perturbation position, generate an airfoil aerodynamic calculation grid, and obtain the lift coefficient and drag coefficient of the perturbed airfoil. The optimal parameter acquisition module is used to establish a simulation optimization design platform, connect to MATLAB software, and set optimization variables and constraints based on the perturbed airfoil, the airfoil aerodynamic calculation grid, and the perturbed airfoil lift coefficient and drag coefficient. Based on the optimization variables and constraints, the optimal parameter values ​​are obtained using a Kriging surrogate model and a genetic algorithm. The airfoil design module is used to optimize the design of a dedicated airfoil for high-speed trains based on the distance range between the upper wall of the high-speed train and the basic high-lift laminar flow airfoil, the installation range of the basic high-lift laminar flow airfoil, and the optimal value of the parameters.

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