A numerical simulation method of aerodynamic characteristics of high-speed rocket sled-track system

Abstract

The application discloses a simulation analysis method for aerodynamic characteristics of a high-speed rocket sled-track system, and establishes a mathematical model and a finite element model of the rocket sled-track system, obtains the dynamic response of the rocket sled through numerical solution, and performs comparison and verification; a fluid domain is constructed according to the geometric shape of the rocket sled and three-dimensional characteristics of a flow field, global grid division of the flow field of the rocket sled is performed, and a finite element model is constructed; an RNG k-ɛ turbulent flow model is adopted, an inlet flow velocity and an outlet pressure boundary are set, aerodynamic drag and its coefficient acting on the rocket sled are analyzed and obtained, and aerodynamic load input is provided; a coupled dynamic model of the rocket sled-track system is constructed, a rigid-flexible coupled model of the sled-track system of a flexible track structure is established; track irregularity numerical excitation is reconstructed, and data of track irregularity of the rocket sled-track system are obtained; initial conditions and boundary conditions are set, different working conditions of the rocket sled under different Mach numbers with or without aerodynamic drag load are simulated, and the motion parameters of the mass center of the rocket sled are obtained. The application provides an analysis method for studying the influence of aerodynamic drag on the dynamic response of the rocket sled-track system.

Description

Technical Field

[0001] This invention relates to multibody system dynamics modeling technology, specifically a simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system. Background Technology

[0002] The rocket sled-track system, as a key high-speed ground test platform, uses a rocket engine to drive a sled carrying test components along a high-precision track, covering the entire speed range from subsonic to hypersonic, providing accurate dynamic performance parameters for aerospace and weapon systems. This system combines the controllability of wind tunnel testing with the environmental realism of flight testing and has been widely used in various high-speed dynamic characteristic tests. However, with the continuous increase in test speed, the dynamic problems exhibited by the system during high-speed operation are becoming increasingly complex. When the rocket sled moves at high speed, the surrounding flow field generates strong aerodynamic loads, which, coupled with track irregularities and nonlinear contact between the sled and track, cause severe vibrations in the system, directly affecting test safety and data reliability. Therefore, research on the aerodynamic characteristics of the rocket sled-track system is of great significance.

[0003] Current analyses of rocket sled systems generally employ multibody dynamics and finite element simulation methods, primarily focusing on sled-track coupling models, track irregularity excitation, and structural vibration characteristics. However, these studies typically simplify aerodynamic loads to constant values ​​or approximate them using empirical formulas, failing to fully consider the dynamic characteristics of aerodynamic loads as a function of Mach number during high-speed operation and their coupling effect with structural vibration. Aerodynamic characteristic studies largely utilize wind tunnel tests and computational fluid dynamics simulations, analyzing rocket sled shape optimization, surface pressure distribution, and flow field structure, providing important basis for aerodynamic shape design. Although this research is relatively in-depth, the correlation analysis between aerodynamic loads and the overall dynamic behavior of the system remains insufficient, and the impact of aerodynamic loads on the dynamic response of complex coupled systems requires further investigation. Summary of the Invention

[0004] This invention proposes a numerical simulation analysis method for the aerodynamic characteristics of a high-speed rocket skid-track system.

[0005] The technical solution for achieving the objective of this invention is: a simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system, characterized by comprising the following steps:

[0006] Step 1: Establish the mathematical model and finite element model of the rocket sled-track system, obtain the dynamic response of the rocket sled through numerical solution, and compare and verify the vertical center of mass acceleration of the mathematical model and the finite element model to ensure the accuracy of the finite element model.

[0007] Step 2: Construct a fluid domain based on the geometric shape and three-dimensional characteristics of the flow field of the rocket sled, perform global mesh generation of the flow field domain of the rocket sled, and construct a fluid dynamics finite element model;

[0008] Step 3: Using the RNG k-ɛ turbulence model, set the inlet velocity and outlet pressure boundaries, and solve to obtain the aerodynamic drag and its coefficient acting on the rocket skid, which is used as the aerodynamic load input.

[0009] Step 4: Construct a coupled dynamic model of the rocket skid-track system, assemble the geometric model into an integral model and define the material properties, and establish a rigid-flexible coupled model of the skid-track system with a flexible track structure by replacing the rigid track with a flexible body.

[0010] Step 5: Based on the power spectral density function of the track irregularity, the numerical excitation of the track irregularity is reconstructed using the trigonometric series method to obtain the data of the track irregularity, which is then input into the rocket skid-track rigid-flexible coupling system.

[0011] Step 6: Set initial and boundary conditions, apply the obtained aerodynamic drag as an external load to the coupled model of the rocket sled-track system, simulate different working conditions of the rocket sled with and without aerodynamic drag load at various Mach numbers, obtain the motion parameters of the rocket sled's center of mass, and analyze the influence of aerodynamic drag on the system's dynamic response.

[0012] Further, in step 1, a mathematical model and a finite element model of the rocket sled-track system are established. The dynamic response of the rocket sled is obtained through numerical solution. The vertical centroid acceleration of the mathematical model and the finite element model are compared and verified to ensure the accuracy of the finite element model. The specific method is as follows: (1) Establish a mathematical model of the rocket sled-track system:

[0013] The skid is simplified as a rigid body, with the center of the skid coordinate system being the skid's centroid. The centers of the front and rear skids coincide with the center of the track. This is a simplified nonlinear calculation model, and calculations are performed based on characteristic parameters while considering aerodynamic effects.

[0014] Aerodynamic forces acting on the rocket sled It is divided into two parts: one part is the aerodynamic drag along the track in the opposite direction to the direction of the skid's movement. The other part is the aerodynamic lift force that is vertically upwards and perpendicular to the horizontal line of the track. The formula for the aerodynamic force is:

[0015] (1)

[0016] The formulas for aerodynamic drag and aerodynamic lift are as follows:

[0017] (2)

[0018] (3)

[0019] in, Let V be the gas density of the environment in which the rocket sled moves, v be the speed of the rocket sled, A be the frontal area, and C be the gas density of the environment in which the rocket sled moves. R C is the drag coefficient. L The lift coefficients are:

[0020] (4)

[0021] (5)

[0022] (6)

[0023] in, For the speed of the rocket sled, For wind speed, , , Let x, y, and z be the components of the rocket sled's velocity on the three coordinate axes. , , Let x represent the components of wind speed on the x, y, and z coordinate axes. The drag coefficient of the skid at zero angle of attack. The angle-of-attack induction coefficient, For relative angle of attack, The lift coefficient of the skid at the angle of attack. The derivative of the lift coefficient;

[0024] The general dynamic equation for the motion of the rocket sled's center of mass is obtained as follows:

[0025] (7)

[0026] in, For the weight of the skid, For the absolute velocity of the sled's center of gravity, The interaction force between the rocket skid and the track. The aerodynamic force on the sled For the weight of the skid itself, For engine thrust, Let be the relative acceleration of the sled's instantaneous center of mass relative to its initial center of mass. Let be the angular velocity of the sled. (1) The relative velocity of the instantaneous center of mass of the sled relative to the initial center of mass; (2) Establish the finite element model of the rocket sled-track system:

[0027] Based on the actual geometric dimensions of the rocket skid, considering factors such as diameter, length, taper, curvature, cross-sectional shape, and structural form, a three-dimensional solid model of the rocket skid, including the fairing, rocket skid, skid, and engine, as well as a three-dimensional solid model of the track, are established. Mesh generation is performed, and a finite element model is established.

[0028] Set the material properties of each part of the rocket skid and track, including density ρ, Poisson's ratio μ, and elastic modulus E; set the system boundary conditions, including the vertically downward gravity acting on the skid, the thrust in the positive direction of the track, and the aerodynamic drag in the negative direction of the track.

[0029] (3) Comparative verification:

[0030] The vertical acceleration-time history curve data of the center of mass of the rocket sled-track system is selected as the verification standard. The vertical acceleration-time history curve obtained by the finite element model simulation under the same parameter settings and boundary conditions is compared with the time history curve calculated by the mathematical model. The error is required to be no more than 15%. If the error exceeds 15%, the parameter values ​​of each equivalent factor need to be modified until the error meets the condition, so as to ensure the accuracy of the finite element model.

[0031] Further, in step 2, a fluid domain is constructed based on the rocket sled's geometric shape and the three-dimensional characteristics of the flow field. A global mesh is then created within the rocket sled's flow field domain, and a finite element model of fluid dynamics is constructed. The specific method is as follows:

[0032] (1) Based on the actual geometric dimensions of the rocket skid, a semi-cylindrical fluid computational domain is constructed around the rocket skid, ensuring that the inlet, outlet, and side boundary of the computational domain are sufficiently far from the surface of the rocket skid:

[0033] The computational domain width of the rocket sled is taken as 30 times the maximum diameter of the rocket sled body, and the length of the flow direction computational domain is taken as 10 times the length of the rocket sled body. The length of the wake region computational domain is 3 times the length of the incoming flow region computational domain, and the gap between the sled and the ground is taken as 0.2 m.

[0034] (2) Mesh generation was performed in Fluent Meshing. The Poly-Hexcore volume mesh generation method was used to generate the mesh. Mesh refinement was performed on the surface of the rocket skid and the near-wall region to establish a fluid dynamics finite element model.

[0035] Further, in step 3, the RNG k-ɛ turbulence model is used to set the inlet velocity and outlet pressure boundaries, and the aerodynamic drag and its coefficient acting on the rocket skid are analyzed and obtained as aerodynamic load input. The specific method is as follows:

[0036] (1) Set the fluid medium as compressible air and use the RNG k-ɛ turbulence model;

[0037] (2) Set the inlet of the computational domain to velocity inlet condition and the outlet to pressure outlet condition, and set the inflow velocity corresponding to different Mach numbers;

[0038] (3) Numerical solution method based on finite volume method, using second-order upwind discretization scheme for discretization solution;

[0039] (4) Solve to obtain the pressure distribution and flow field characteristics on the surface of the rocket skid, and then obtain the aerodynamic drag acting on the rocket skid and the aerodynamic drag coefficient at the corresponding Mach number, as the aerodynamic load input.

[0040] Further, in step 4, a coupled dynamic model of the rocket sled-track system is constructed. The geometric model is assembled into a single model, and material properties are defined. By replacing the rigid track with a flexible body, a rigid-flexible coupled model of the sled-track system with a flexible track structure is established. The specific method is as follows:

[0041] (1) Establish a dynamic model of the rocket sled-track system in Adams software, and position and constrain it according to the actual assembly relationship;

[0042] (2) Replace the rigid track with a flexible body, calculate its modal information using the finite element method, generate a modal neutral file, import it into the coupled dynamics model to complete the replacement of the flexible track, and establish a rigid-flexible coupling model.

[0043] Further, in step 5, based on the power spectral density function of the orbital irregularity, the numerical excitation of the orbital irregularity is reconstructed using the trigonometric series method to obtain the orbital irregularity data of the rocket sled-orbit system, which is then input into the rigid-flexible coupling system of the rocket sled-orbit system. The specific method is as follows:

[0044] (1) Determine the spatial frequency range and amplitude characteristics of track irregularities based on the power spectral density function of track irregularities;

[0045] (2) The power spectral density function is reconstructed into a spatial domain signal using a stochastic process simulation method, and the track irregularities are simulated and reconstructed using the trigonometric series method:

[0046] Calculate PSD function Standard deviation :

[0047] (8)

[0048] Obtain a normal random variable with a mean of 0. and random variables uniformly distributed between 0 and 2π ;

[0049] Calculate the frequency interval and the first Each sampling frequency:

[0050] (9)

[0051] (10)

[0052] Substituting into the trigonometric series formula, we obtain the random time series with irregular orbits. :

[0053] (11)

[0054] (3) Compare and verify the track irregularity values ​​obtained by reconstructing based on the trigonometric series method with the measured track irregularity values;

[0055] (4) The generated track irregularity data is applied to the track of the rocket skid-track system in the form of displacement excitation.

[0056] Further, in step 6, initial and boundary conditions are set, and the obtained aerodynamic drag is applied as an external load to the coupled model of the rocket sled-track system. Simulations are performed on the rocket sled under different operating conditions with and without aerodynamic drag load at various Mach numbers to obtain the motion parameters of the rocket sled's center of mass and analyze the degree of influence of aerodynamic drag on the system's dynamic response. The specific method is as follows:

[0057] (1) Apply the aerodynamic drag data at different Mach numbers obtained in step 3 as an external excitation to the center of mass or aerodynamic center of the rocket skid; apply the track irregularity data obtained in step 5 as a displacement excitation to the rigid-flexible coupling dynamic model of the rocket skid-track system.

[0058] (2) Set the speed of the rocket skid along the track, set the simulation time step and total duration; perform numerical simulations for subsonic, transonic and supersonic conditions with and without aerodynamic drag load.

[0059] (3) By comparing and analyzing the simulation results, the key dynamic response of the system's center of mass acceleration during high-speed operation is analyzed through the time history curves of the lateral and vertical acceleration of the rocket skid's center of mass. The characteristics of the skid track's dynamic response under different speed states, as well as the degree of influence of aerodynamic drag on the system's vibration and dynamic stability, are obtained.

[0060] A numerical simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system is provided. Based on the aforementioned numerical simulation analysis method for the aerodynamic characteristics of the high-speed rocket sled-track system, numerical simulation analysis of the aerodynamic characteristics of the high-speed rocket sled-track system is achieved.

[0061] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it performs a simulation analysis of the aerodynamic characteristics of the high-speed rocket sled-track system based on the aforementioned simulation analysis method for the aerodynamic characteristics of the high-speed rocket sled-track system.

[0062] A computer-readable storage medium storing a computer program thereon, which, when executed by a processor, performs a simulation analysis of the aerodynamic characteristics of a high-speed rocket sled-track system based on the aforementioned simulation analysis method for the aerodynamic characteristics of the high-speed rocket sled-track system.

[0063] Compared with the prior art, the present invention has the following significant advantages: (1) The RNG k-ε turbulence model is used for CFD numerical simulation to systematically study the aerodynamic characteristics of the rocket skid under subsonic, transonic and supersonic conditions. It can accurately capture the complex flow phenomena around the rocket skid under high-speed conditions and improve the calculation accuracy of aerodynamic loads. (2) The trigonometric series method is used to reconstruct the numerical excitation of track irregularities, generate excitation inputs that match the amplitude and distribution characteristics of measured data, and input them into the rigid-flexible coupled multibody dynamics model. This can more accurately reflect the dynamic coupling behavior of the system in actual operation, thereby improving the reliability of the simulation results. (3) The established rocket skid-track system model considers factors such as aerodynamic drag, track irregularities and rigid-flexible coupling effects, and realizes the simulation of the system under high-speed operation. By changing the parameter settings, the rigid-flexible coupled dynamic response of the rocket skid-track system under different Mach numbers and aerodynamic drag can be accurately calculated. Attached Figure Description

[0064] Figure 1 This is a flowchart of the simulation analysis of the aerodynamic characteristics of a high-speed rocket sled-track system.

[0065] Figure 2 (a) Front view of the rocket sled model design; (b) Top view of the rocket sled model design.

[0066] Figure 3 This is a finite element model of a rocket sled.

[0067] Figure 4 (a) is a schematic diagram of the track model and the skid-rail coupling; (b) is a schematic diagram of the track model and the skid-rail coupling.

[0068] Figure 5 The vertical centroid acceleration diagram is shown in the mathematical model and finite element model of the rocket sled-track system.

[0069] Figure 6(a) is a schematic diagram of the fluid computation domain of the rocket sled; (b) is a front view of the fluid computation domain of the rocket sled; and (c) is a perspective view of the fluid computation domain of the rocket sled.

[0070] Figure 7 This is a two-dimensional grid diagram of the rocket skid.

[0071] Figure 8 A 3D mesh diagram of the rocket skid.

[0072] Figure 9 This is a graph showing the simulated aerodynamic drag coefficient as a function of Mach number.

[0073] Figure 10 This is a velocity vector cloud diagram of the rocket sled.

[0074] Figure 11 This is a surface pressure cloud map of the rocket skid.

[0075] Figure 12 This is a model diagram of a rocket sled-orbit system.

[0076] Figure 13 This is a rigid-flexible coupling model diagram of a skid-rail system with a flexible track structure.

[0077] Figure 14 This is a flowchart of the non-smooth reconstruction process based on the trigonometric series method.

[0078] Figure 15 This is a comparison chart of track irregularity values ​​based on the trigonometric series method.

[0079] Figure 16 (a) Time history curve of the sled's center of mass acceleration when Ma=0.6; (b) Time history curve of the sled's vertical center of mass acceleration when Ma=0.6; Figure 16 (b) is the time history curve of the lateral centroid acceleration of the skid when Ma=0.6.

[0080] Figure 17 (a) Time history curves of the sled's center of mass acceleration when Ma=1.2; (b) Time history curves of the sled's vertical center of mass acceleration when Ma=1.2; (c) Time history curves of the sled's lateral center of mass acceleration when Ma=1.2. Detailed Implementation

[0082] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0083] A numerical simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system, comprising the following steps:

[0084] Step 1: Establish the mathematical model and finite element model of the rocket sled-track system. Obtain the dynamic response of the rocket sled through numerical solution. Compare and verify the vertical center of mass acceleration of the mathematical model and the finite element model to ensure the accuracy of the finite element model. The specific method is as follows:

[0085] (1) Establishing a mathematical model of the rocket sled-orbit system:

[0086] The skid is simplified as a rigid body, with the center of the skid coordinate system being the skid's centroid. The centers of the front and rear skids coincide with the center of the track. This is a simplified nonlinear calculation model, and calculations are performed based on characteristic parameters while considering aerodynamic effects.

[0087] Aerodynamic forces acting on the rocket sled It is divided into two parts: one part is the aerodynamic drag along the track in the opposite direction to the direction of the skid's movement. The other part is the aerodynamic lift force that is vertically upwards and perpendicular to the horizontal line of the track. The formula for the aerodynamic force is:

[0088] (1)

[0089] The formulas for air resistance and aerodynamic lift are as follows:

[0090] (2)

[0091] (3)

[0092] in, Let V be the gas density of the environment in which the rocket sled moves, v be the speed of the rocket sled, A be the frontal area, and C be the gas density of the environment in which the rocket sled moves. R C is the drag coefficient. L The lift coefficients are:

[0093] (4)

[0094] (5)

[0095] (6)

[0096] in, For the speed of the rocket sled, For wind speed, , , Let x, y, and z be the components of the rocket sled's velocity on the three coordinate axes. , , Let x represent the components of wind speed on the x, y, and z coordinate axes. The drag coefficient of the skid at zero angle of attack. The angle-of-attack induction coefficient, For relative angle of attack, The lift coefficient of the skid at the angle of attack. The derivative of the lift coefficient;

[0097] The general dynamic equation for the motion of the rocket sled's center of mass is obtained as follows:

[0098] (7)

[0099] in, For the weight of the skid, For the absolute velocity of the sled's center of gravity, The interaction force between the rocket skid and the track. The aerodynamic force on the sled For the weight of the skid itself, For engine thrust, Let be the relative acceleration of the sled's instantaneous center of mass relative to its initial center of mass. Let be the angular velocity of the sled. Let be the relative velocity of the sled's instantaneous center of mass relative to its initial center of mass;

[0100] (2) Establish the finite element model of the rocket sled-orbit system:

[0101] Based on the actual geometric dimensions of the rocket skid, considering factors such as diameter, length, taper, curvature, cross-sectional shape, and structural form, a three-dimensional solid model of the rocket skid, including the fairing, rocket skid, skid, and engine, as well as a three-dimensional solid model of the track, are established. Mesh generation is performed, and a finite element model is established.

[0102] Set the material properties of each part of the rocket skid and track, including density ρ, Poisson's ratio μ, and elastic modulus; set the system boundary conditions, including the vertically downward gravity acting on the skid, the thrust in the positive direction of the track, and the aerodynamic drag in the negative direction of the track.

[0103] (3) Comparative verification:

[0104] The vertical acceleration-time history curve data of the center of mass of the rocket sled-track system is selected as the verification standard. The vertical acceleration-time history curve obtained by the finite element model simulation under the same parameter settings and boundary conditions is compared with the time history curve calculated by the mathematical model. The error is required to be no more than 15%. If the error exceeds 15%, the parameter values ​​of each equivalent factor need to be modified until the error meets the condition, so as to ensure the accuracy of the finite element model.

[0105] Step 2: Construct a fluid domain based on the rocket sled's geometric shape and three-dimensional flow field characteristics, perform global mesh generation of the rocket sled's flow field domain, and construct a fluid dynamics finite element model. The specific method is as follows:

[0106] (1) Based on the actual geometric dimensions of the rocket skid, a semi-cylindrical fluid computational domain is constructed around the rocket skid, ensuring that the inlet, outlet, and side boundary of the computational domain are sufficiently far from the surface of the rocket skid:

[0107] The computational domain width of the rocket sled is taken as 30 times the maximum diameter of the rocket sled body, and the length of the flow direction computational domain is taken as 10 times the length of the rocket sled body. The length of the wake region computational domain is 3 times the length of the incoming flow region computational domain, and the gap between the sled and the ground is taken as 0.2 m.

[0108] (2) Mesh generation was performed in Fluent Meshing. The Poly-Hexcore volume mesh generation method was used to generate the mesh. Mesh refinement was performed on the surface of the rocket skid and the near-wall region to establish a fluid dynamics finite element model.

[0109] Step 3: Using the RNG k-ɛ turbulence model, the inlet velocity and outlet pressure boundaries are set, and the aerodynamic drag acting on the rocket skid and its coefficient are analyzed and obtained as aerodynamic load input. The specific method is as follows:

[0110] (1) Set the fluid medium as compressible air and use the RNG k-ɛ turbulence model;

[0111] (2) Set the inlet of the computational domain to velocity inlet condition and the outlet to pressure outlet condition, and set the inflow velocity corresponding to different Mach numbers;

[0112] (3) Numerical solution method based on finite volume method, using second-order upwind discretization scheme for discretization solution;

[0113] (4) Solve to obtain the pressure distribution and flow field characteristics on the surface of the rocket skid, and then obtain the aerodynamic drag acting on the rocket skid and the aerodynamic drag coefficient at the corresponding Mach number, as the aerodynamic load input.

[0114] Step 4: Construct a coupled dynamic model of the rocket sled-track system. Assemble the geometric model into a single model and define material properties. By replacing the rigid track with a flexible body, establish a rigid-flexible coupled model of the sled-track system with a flexible track structure. The specific method is as follows:

[0115] (1) Establish a dynamic model of the rocket sled-track system in Adams software, and position and constrain it according to the actual assembly relationship;

[0116] (2) Replace the rigid track with a flexible body, calculate its modal information using the finite element method, generate a modal neutral file, import it into the coupled dynamics model to complete the replacement of the flexible track, and establish a rigid-flexible coupling model.

[0117] Step 5: Based on the power spectral density function of the orbital irregularity, the numerical excitation of the orbital irregularity is reconstructed using the trigonometric series method to obtain the orbital irregularity data of the rocket sled-orbit system, which is then input into the rigid-flexible coupling system of the rocket sled-orbit system. The specific method is as follows:

[0118] (1) Determine the spatial frequency range and amplitude characteristics of track irregularities based on the power spectral density function of track irregularities;

[0119] (2) The power spectral density function is reconstructed into a spatial domain signal using a stochastic process simulation method, and the track irregularities are simulated and reconstructed using the trigonometric series method:

[0120] Calculate PSD function Standard deviation :

[0121] (8)

[0122] Obtain a normal random variable with a mean of 0. and random variables uniformly distributed between 0 and 2π ;

[0123] Calculate the frequency interval and the first Each sampling frequency:

[0124] (9)

[0125] (10)

[0126] Substituting into the trigonometric series formula, we obtain the random time series with irregular orbits. :

[0127] (11)

[0128] (3) Compare and verify the track irregularity values ​​obtained by reconstructing based on the trigonometric series method with the measured track irregularity values;

[0129] (4) The generated track irregularity data is applied to the track of the rocket skid-track system in the form of displacement excitation.

[0130] Step 6: Set initial and boundary conditions, and apply the obtained aerodynamic drag as an external load to the coupled model of the rocket sled-track system. Simulate different operating conditions of the rocket sled with and without aerodynamic drag load at various Mach numbers to obtain the motion parameters of the rocket sled's center of mass and analyze the influence of aerodynamic drag on the system's dynamic response. The specific method is as follows:

[0131] (1) Apply the aerodynamic drag data at different Mach numbers obtained in step 3 as an external excitation to the center of mass or aerodynamic center of the rocket skid; apply the track irregularity data obtained in step 5 as a displacement excitation to the rigid-flexible coupling dynamic model of the rocket skid-track system.

[0132] (2) Set the speed of the rocket skid along the track, set the simulation time step and total duration; perform numerical simulations for subsonic, transonic and supersonic conditions with and without aerodynamic drag load.

[0133] (3) By comparing and analyzing the simulation results, the key dynamic response of the system's center of mass acceleration during high-speed operation is analyzed through the time history curves of the lateral and vertical acceleration of the rocket skid's center of mass. The characteristics of the skid track's dynamic response under different speed states, as well as the degree of influence of aerodynamic drag on the system's vibration and dynamic stability, are obtained. Example

[0134] To verify the effectiveness of the present invention, the following embodiments were carried out.

[0135] like Figure 1 As shown in the embodiments of this application, a simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system is provided, specifically including the following steps:

[0136] (1) Based on the design scheme of the rocket skid-track system, three-dimensional solid modeling was performed using Solidworks software, and the results were compared and verified with those obtained from mathematical model calculations.

[0137] (2) Based on the geometric shape and three-dimensional characteristics of the flow field of the rocket skid, a fluid domain was constructed. Ansys software was used to perform global mesh generation of the flow field domain of the rocket skid and to construct a finite element model.

[0138] (3) The RNG k-ɛ turbulence model was adopted. The inlet velocity boundary and outlet pressure boundary were set in Fluent software. The second-order upwind discretization scheme was used to solve the discretization problem based on the finite volume method and to conduct numerical simulation.

[0139] (4) The velocity vector distribution and surface pressure distribution around the rocket skid are obtained by simulation, and the aerodynamic drag and drag coefficient at different Mach numbers are calculated to generate aerodynamic load data.

[0140] (5) Construct a coupled dynamic model of the rocket skid-track system in Adams software, assemble the geometric model into an integral model and define the material properties to establish a rigid-flexible coupled model of the skid-track system with flexible track structure.

[0141] (6) Based on the trigonometric series method, the numerical excitation of the trajectory irregularity was reconstructed using Matlab software to obtain the trajectory irregularity data of the rocket skid-track system;

[0142] (7) Apply the track irregularity data and aerodynamic load as external excitation to the coupled dynamic model, and set the initial conditions and boundary conditions to simulate the different working conditions of the rocket skid with and without aerodynamic drag load at various Mach numbers.

[0143] (8) Compare and analyze the simulation results of each working condition, obtain the motion parameters of the rocket skid's center of mass, and analyze the influence of aerodynamic drag on the dynamic response of the rocket skid-track system.

[0144] An analysis of a certain monorail rocket sled-track system is conducted, and the rocket sled model design scheme is as follows: Figure 2 As shown, without changing the main components, the finite element model of the rocket sled is obtained by considering its external dimensions, including diameter, length, taper, and degree of curvature, as well as its cross-sectional shape and structural form. Figure 3 As shown.

[0145] The coupling characteristics of the rocket sled-orbit system are mainly manifested in the contact interaction between the two. A schematic diagram of the orbital model is shown below. Figure 4 As shown in Table 1, the material parameters of the rocket sled-track system are as follows.

[0146] Table 1 Material parameters of the rocket sled-orbit system

[0147]

[0148] The dynamic model of the rocket sled-track system is simplified by treating the sled as a rigid body with its coordinate system centered at its center of mass. The centers of the front and rear sleds coincide with the center of the track. Assuming a simplified nonlinear calculation model, the same parameter settings and boundary conditions are applied to the single-track rocket sled-track system model for calculation. The vertical acceleration of the center of mass in both the mathematical model and the finite element model of the single-track rocket sled-track system is obtained as follows: Figure 5 As shown.

[0149] Based on the fundamental characteristics of the flow field, the external computational domain of the flow field is designed as a semi-cylindrical computational domain, divided into the incoming flow region and the wake region. The fluid computational domain of the rocket sled is as follows: Figure 6 As shown, the geometric model of the rocket sled and its fluid domain was meshed using the Poly-Hexcore volume mesh generation method. The two-dimensional mesh diagram of the rocket sled is shown below. Figure 7As shown, the three-dimensional mesh diagram of the rocket skid is as follows: Figure 8 As shown.

[0150] The RNG k-ɛ turbulence model was adopted, with the inlet and outlet of the flow domain set as velocity inlet and pressure outlet, respectively. The ground surface was set as a smooth wall condition. The flow was discretized using a second-order upwind discretization scheme based on the finite volume method. The SIMPLE algorithm based on the prediction-correction two-step calculation method was selected for the solution. The numerical solution parameters are shown in Table 2.

[0151] Table 2 Numerical solution parameters

[0152]

[0153] Numerical simulations were used to obtain the aerodynamic drag and drag coefficient values ​​of the monorail rocket skid at different Mach numbers. The aerodynamic drag values ​​at different Mach numbers are shown in Table 3. The simulated aerodynamic drag coefficients were fitted to a curve showing the variation with Mach number. Figure 9 As shown, the aerodynamic drag data obtained from this simulation is used as the input for external load conditions. The velocity vector distribution and surface pressure distribution around the rocket sled are obtained through simulation. The velocity vector contour map of the rocket sled is shown below. Figure 10 As shown, the surface pressure cloud map of the rocket skid is as follows: Figure 11 As shown.

[0154] Table 3 Aerodynamic drag values ​​at different Mach numbers

[0155]

[0156] Rocket sled-orbit system model diagram as follows Figure 12 As shown in Table 4, the main structural parameters of the monorail rocket sled-track system are as follows. The track component of the system is exported separately, and the various parts of the rocket sled are compressed to save the track's pose information within the assembly. Then, a model analysis of the track is performed. By selecting geometric structures to define remote points and establishing an exported set, a modal neutral file is obtained through solving. This file is then used to replace the track component, achieving flexible track processing. The rigid-flexible coupling model diagram of the sled-track system with the flexible track structure is shown below. Figure 13 As shown.

[0157] Table 4. Main structural parameters of the monorail rocket sled-orbit system

[0158]

[0159] The specific steps for reconstructing a PSD function into a spatial domain signal using the trigonometric series method can be represented by a flowchart. The flowchart for the non-coherent reconstruction based on the trigonometric series method is shown below. Figure 12 As shown, the calculated and measured values ​​of track irregularities are compared as follows: Figure 13As shown, the simulated track irregularity data is applied to the skid using spline curves. The excitation of track irregularity is transmitted to the rocket skid through the skid, thus realizing the input of track irregularity.

[0160] Initial and boundary conditions were set, and the obtained aerodynamic drag was applied as an external load to the coupled model of the rocket sled-track system. The reconstructed track irregularity data was applied as displacement excitation to the rigid-flexible coupled dynamic model of the rocket sled-track system. Simulations were performed on the rocket sled under different operating conditions with and without aerodynamic drag load at various Mach numbers to obtain the motion parameters of the rocket sled's center of mass. The time history curves of the lateral and vertical acceleration of the rocket sled's center of mass were obtained. The time history curve of the sled's center of mass acceleration at Ma=0.6 is shown below. Figure 16 As shown, the time history curve of the sled's center of mass acceleration when Ma=1.2 is as follows: Figure 17 As shown, by analyzing the key dynamic response of the system's center of mass acceleration during high-speed operation, the characteristics of the skid-rail dynamic response at different speeds can be obtained, as well as the degree of influence of aerodynamic drag on the system's vibration and dynamic stability.

[0161] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0162] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A numerical simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system, characterized in that, Includes the following steps: Step 1: Establish the mathematical model and finite element model of the rocket sled-track system, obtain the dynamic response of the rocket sled through numerical solution, and compare and verify the vertical center of mass acceleration of the mathematical model and the finite element model to ensure the accuracy of the finite element model. Step 2: Construct a fluid domain based on the geometric shape and three-dimensional characteristics of the flow field of the rocket sled, perform global mesh generation of the flow field domain of the rocket sled, and construct a fluid dynamics finite element model; Step 3: Using the RNG k-ɛ turbulence model, set the inlet velocity and outlet pressure boundaries, and solve to obtain the aerodynamic drag and its coefficient acting on the rocket skid, which is used as the aerodynamic load input. Step 4: Construct a coupled dynamic model of the rocket skid-track system, assemble the geometric model into an integral model and define the material properties, and establish a rigid-flexible coupled model of the skid-track system with a flexible track structure by replacing the rigid track with a flexible body. Step 5: Based on the power spectral density function of the track irregularity, the numerical excitation of the track irregularity is reconstructed using the trigonometric series method to obtain the data of the track irregularity, which is then input into the rocket skid-track rigid-flexible coupling system. Step 6: Set initial and boundary conditions, apply the obtained aerodynamic drag as an external load to the coupled model of the rocket sled-track system, simulate different working conditions of the rocket sled with and without aerodynamic drag load at various Mach numbers, obtain the motion parameters of the rocket sled's center of mass, and analyze the influence of aerodynamic drag on the system's dynamic response.

2. The simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system according to claim 1, characterized in that, Step 1: Establish the mathematical model and finite element model of the rocket sled-track system. Obtain the dynamic response of the rocket sled through numerical solution. Compare and verify the vertical center of mass acceleration of the mathematical model and the finite element model to ensure the accuracy of the finite element model. The specific method is as follows: (1) Establishing a mathematical model of the rocket sled-orbit system: The sled is simplified as a rigid body, with the center of the sled coordinate system being the sled's centroid, and the centers of the front and rear shoes coinciding with the center of the track. Aerodynamic forces acting on the rocket sled It is divided into two parts: one part is the aerodynamic drag along the track in the opposite direction to the direction of the skid's movement. The other part is the aerodynamic lift force that is vertically upwards and perpendicular to the horizontal line of the track. The formula for the aerodynamic force is: (1) The formulas for aerodynamic drag and aerodynamic lift are as follows: (2) (3) in, Let V be the gas density of the environment in which the rocket sled moves, v be the speed of the rocket sled, A be the frontal area, and C be the gas density of the environment in which the rocket sled moves. R C is the drag coefficient. L The lift coefficients are: (4) (5) (6) in, For the speed of the rocket sled, For wind speed, , , Let x, y, and z be the components of the rocket sled's velocity on the three coordinate axes. , , Let x represent the components of wind speed on the x, y, and z coordinate axes. The drag coefficient of the skid at zero angle of attack. The angle-of-attack induction coefficient, For relative angle of attack, The lift coefficient of the skid at the angle of attack. The derivative of the lift coefficient; The general dynamic equation for the motion of the rocket sled's center of mass is: (7) in, For the weight of the skid, For the absolute velocity of the sled's center of gravity, The interaction force between the rocket skid and the track. The aerodynamic force on the sled For the weight of the skid itself, For engine thrust, Let be the relative acceleration of the sled's instantaneous center of mass relative to its initial center of mass. Let be the angular velocity of the sled. Let be the relative velocity of the sled's instantaneous center of mass relative to its initial center of mass; (2) Establish the finite element model of the rocket sled-orbit system: Based on the actual geometric dimensions of the rocket skid, considering factors such as diameter, length, taper, curvature, cross-sectional shape, and structural form, a three-dimensional solid model of the rocket skid, including the fairing, rocket skid, skid, and engine, as well as a three-dimensional solid model of the track, are established. Mesh generation is performed, and a finite element model is established. Set the material properties of each part of the rocket skid and track, including density ρ, Poisson's ratio μ, and elastic modulus E; Set system boundary conditions, including the vertically downward gravity acting on the skid, the thrust in the positive direction of the rail, and the aerodynamic drag in the negative direction of the rail. (3) Comparative verification: The vertical acceleration-time history curve data of the center of mass of the rocket sled-track system is selected as the verification standard. The vertical acceleration-time history curve obtained by the finite element model simulation under the same parameter settings and boundary conditions is compared with the time history curve calculated by the mathematical model. The error is required to be no more than 15%. If the error exceeds 15%, the parameter values ​​of each equivalent factor need to be modified until the error meets the condition, so as to ensure the accuracy of the finite element model.

3. The simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system according to claim 1, characterized in that, Step 2: Construct a fluid domain based on the rocket sled's geometric shape and three-dimensional flow field characteristics, perform global mesh generation of the rocket sled's flow field domain, and construct a fluid dynamics finite element model. The specific method is as follows: (1) Based on the actual geometric dimensions of the rocket skid, a semi-cylindrical fluid computational domain is constructed around the rocket skid, ensuring that the inlet, outlet, and side boundary of the computational domain are sufficiently far from the surface of the rocket skid: The computational domain width of the rocket skid is taken as 30 times the maximum diameter of the rocket skid body, and the length of the flow direction computational domain is taken as 10 times the length of the rocket skid body. The length of the wake region computational domain is 3 times the length of the incoming flow region computational domain, and the gap between the skid and the ground is taken as 0.2m. (2) Mesh generation was performed in Fluent Meshing. The Poly-Hexcore volume mesh generation method was used to generate the mesh. Mesh refinement was performed on the surface of the rocket skid and the near-wall region to establish a fluid dynamics finite element model.

4. The simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system according to claim 1, characterized in that, Step 3: Using the RNG k-ɛ turbulence model, setting the inlet velocity and outlet pressure boundaries, solve for the aerodynamic drag acting on the rocket skid and its coefficient, which is used as the aerodynamic load input. The specific method is as follows: (1) Set the fluid medium as compressible air and use the RNG k-ɛ turbulence model; (2) Set the inlet of the computational domain to velocity inlet condition and the outlet to pressure outlet condition, and set the inflow velocity corresponding to different Mach numbers; (3) Numerical solution method based on finite volume method, using second-order upwind discretization scheme for discretization solution; (4) Solve to obtain the pressure distribution and flow field characteristics on the surface of the rocket skid, and then obtain the aerodynamic drag acting on the rocket skid and the aerodynamic drag coefficient at the corresponding Mach number, as the aerodynamic load input.

5. The simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system according to claim 1, characterized in that, Step 4: Construct a coupled dynamic model of the rocket sled-track system. Assemble the geometric model into a single model and define material properties. By replacing the rigid track with a flexible body, establish a rigid-flexible coupled model of the sled-track system with a flexible track structure. The specific method is as follows: (1) Establish a dynamic model of the rocket sled-track system in Adams software, and position and constrain it according to the actual assembly relationship; (2) Replace the rigid track with a flexible body, calculate its modal information using the finite element method, generate a modal neutral file, import it into the coupled dynamics model to complete the replacement of the flexible track, and establish a rigid-flexible coupling model.

6. The simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system according to claim 1, characterized in that, Step 5: Based on the power spectral density function of the orbital irregularity, the numerical excitation of the orbital irregularity is reconstructed using the trigonometric series method to obtain the orbital irregularity data of the rocket sled-orbit system, which is then input into the rigid-flexible coupling system of the rocket sled-orbit system. The specific method is as follows: (1) Determine the spatial frequency range and amplitude characteristics of track irregularities based on the power spectral density function of track irregularities; (2) The power spectral density function is reconstructed into a spatial domain signal using a stochastic process simulation method, and the track irregularities are simulated and reconstructed using the trigonometric series method: Calculate PSD function Standard deviation : (8) Obtain a normal random variable with a mean of 0. and random variables uniformly distributed between 0 and 2π ; Calculate the frequency interval and the first Each sampling frequency: (9) (10) Substituting into the trigonometric series formula, we obtain the random time series with irregular orbits. : (11) (3) Compare and verify the track irregularity values ​​obtained by reconstructing based on the trigonometric series method with the measured track irregularity values; (4) The generated track irregularity data is applied to the track of the rocket skid-track system in the form of displacement excitation.

7. The simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system according to claim 1, characterized in that, Step 6: Set initial and boundary conditions, and apply the obtained aerodynamic drag as an external load to the coupled model of the rocket sled-track system. Simulate different operating conditions of the rocket sled with and without aerodynamic drag load at various Mach numbers to obtain the motion parameters of the rocket sled's center of mass and analyze the influence of aerodynamic drag on the system's dynamic response. The specific method is as follows: (1) Apply the aerodynamic drag data at different Mach numbers obtained in step 3 as an external excitation to the center of mass or aerodynamic center of the rocket skid; apply the track irregularity data obtained in step 5 as a displacement excitation to the rigid-flexible coupling dynamic model of the rocket skid-track system. (2) Set the speed of the rocket skid along the track, set the simulation time step and total duration; perform numerical simulations for subsonic, transonic and supersonic conditions with and without aerodynamic drag load. (3) By comparing and analyzing the simulation results, the key dynamic response of the system's center of mass acceleration during high-speed operation is analyzed through the time history curves of the lateral and vertical acceleration of the rocket skid's center of mass. The characteristics of the skid track's dynamic response under different speed states, as well as the degree of influence of aerodynamic drag on the system's vibration and dynamic stability, are obtained.

8. The simulation and analysis system for the aerodynamic characteristics of a high-speed rocket sled-track system according to claim 1, characterized in that, Based on the simulation analysis method for the aerodynamic characteristics of the high-speed rocket sled-track system according to any one of claims 1-7, the simulation analysis of the aerodynamic characteristics of the high-speed rocket sled-track system is realized, including 6 modules that execute steps 1 to 6 respectively.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it performs a simulation analysis of the aerodynamic characteristics of the high-speed rocket sled-track system based on the simulation analysis method for the aerodynamic characteristics of the high-speed rocket sled-track system according to any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, it performs a simulation analysis of the aerodynamic characteristics of a high-speed rocket sled-track system based on the simulation analysis method for the aerodynamic characteristics of a high-speed rocket sled-track system according to any one of claims 1-7.

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