Rocket boost separation dynamic aerodynamic simulation method

Abstract

The application discloses a rocket boosting separation dynamic aerodynamic simulation method, selects a rocket core stage body coordinate system as a dynamic reference system, and simultaneously obtains a separation motion track and time-varying flow field data of a rocket booster through non-steady aerodynamic simulation. The application can be applied to the kinematic analysis of bundled rocket boosting separation and the load design of the surfaces of the rocket core stage and the booster, avoids the aerodynamic force interpolation deviation problem in the current rocket boosting separation track calculation, obtains the time-varying aerodynamic load of the surfaces of the rocket core stage and the booster in the boosting separation process, and improves the calculation precision of the rocket boosting separation track and the rocket body load design precision.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rocket boost separation technology, and particularly relates to a rocket boost separation dynamic aerodynamic simulation method, which can avoid the aerodynamic force interpolation deviation problem in the calculation of the rocket boost separation trajectory and is mainly used for rocket boost separation scheme analysis and rocket body load design. BACKGROUND

[0002] The bundled rocket refers to bundling a plurality of boosters around the rocket core stage to effectively improve the rocket carrying capacity. When the rocket flies to the set height, the boost engine is shut down, the side thrust rockets located at the head and tail of the booster are started, and the high-temperature and high-pressure gas sprayed out enables the booster to realize separation in a short time. After the high-temperature and high-pressure gas sprayed out by the side thrust rocket reaches the surface of the core stage, a local severe aerodynamic load is formed and changes with the relative position of the booster and the rocket core stage.

[0003] In the traditional boost separation trajectory calculation, aerodynamic simulation is often used to obtain the boost steady aerodynamic force coefficients under certain fixed inflow conditions, and interpolation algorithms are used to obtain the aerodynamic force thermal data in the separation process. On the other hand, the local aerodynamic load generated by the side thrust rocket jet flow needs to be evaluated through ground thermal test, which is to take the rocket core stage as the reference system, and the boosters are located at different characteristic positions to carry out ground ignition test. The above-mentioned aerodynamic simulation method and jet flow test method both belong to the design idea of "point to line, line to surface", which not only introduces interpolation errors, but also the simulation and test results cannot reflect the time-varying characteristics of the aerodynamic force thermal and local aerodynamic load in the boost separation process.

[0004] If the boost separation trajectory calculation is combined with dynamic aerodynamic simulation, the boost separation trajectory can be obtained through aerodynamic simulation, and the time-varying data of the local aerodynamic load of the rocket body in the boost separation process can also be obtained. With the development of computational fluid dynamics and dynamic mesh method, the above-mentioned idea is already feasible. The existing aerodynamic simulation solver already has a dynamic mesh module supporting multi-body motion, and the boost motion parameters in the body coordinate system of the rocket core stage can be solved by using numerical algorithms in the secondary development function, so as to realize the dynamic aerodynamic simulation of the rocket boost separation. SUMMARY

[0005] The purpose of the present application is to solve the aerodynamic force interpolation deviation problem in the current rocket boost separation trajectory calculation, make up for the insufficient understanding of the time-varying characteristics of the boost separation process in the original design method, and the new method can simultaneously obtain the rocket boost separation motion trajectory and time-varying flow field data, which is suitable for rocket boost separation scheme analysis and rocket body aerodynamic load design.

[0006] The technical scheme of the present application is: a rocket boost separation dynamic aerodynamic simulation method, comprising:

[0007] According to the aerodynamic shape of the rocket, a full-rocket aerodynamic simulation model before boost separation is established;

[0008] A dynamic mesh method for boost separation dynamic aerodynamic simulation is determined, and the obtained full-rocket aerodynamic simulation model is divided into topology and simulation mesh is generated;

[0009] The obtained simulation mesh is imported into an aerodynamic simulation solver, and boundary condition setting is completed;

[0010] The boundary conditions include the incoming flow velocity, pressure, temperature of the full-rocket simulation model, and the total pressure and total temperature of the inlet of each engine;

[0011] The turbulence model and solution format are set in the aerodynamic simulation solver;

[0012] The inertial force term of the boost dynamics equation in the non-inertial system is obtained with the rocket core body coordinate system as the dynamic reference system, and the secondary development module of the aerodynamic simulation solver is used to discretely solve the velocity and angular velocity of the boost;

[0013] The inertial force term of the fluid mechanics momentum equation in the non-inertial system is obtained with the rocket core body coordinate system as the dynamic reference system, and the inertial force term is added in the form of a momentum equation source term in the extended module of the aerodynamic simulation solver;

[0014] Based on the aerodynamic simulation settings and boost motion solving settings, the time step is selected, the unsteady dynamic aerodynamic simulation is performed, and the boost centroid displacement, velocity, acceleration, angle, angular velocity, angular acceleration are output in real time, and the flow field pressure, temperature and rocket body aerodynamic load are extracted from the simulation results.

[0015] The dynamic mesh method used in the establishment of boost separation dynamic aerodynamic simulation specifically adopts a grid reconstruction method, and the process is as follows: according to the geometric characteristics of the aerodynamic simulation model, four spin bodies are used to wrap four boosters respectively, so that the fluid domain of the aerodynamic simulation model is divided into five parts, which are the background domain containing the rocket core and four motion domains wrapping the boosters; unstructured mesh of the aerodynamic simulation model is generated, the local area rich in flow field details is grid-encrypted, and the wall boundary layer is set on the surface of the rocket core and the boosters; during the calculation, the motion parameters of the boosters are assigned to the motion domains wrapping the boosters, the internal grid of the motion domain follows the rigid motion of the boosters, and the grid reconstruction is completed in the background domain grid.

[0016] According to the flight speed vector of the rocket core during the boost separation process The incoming flow speed vector of the simulation model is set It refers to taking the rocket core body coordinate system as the dynamic system, keeping the incoming flow boundary of the simulation model stationary, and setting the velocity vector of the incoming flow boundary in the dynamic system.

[0017] The inertia force term of the booster dynamics equation in the non-inertial system is obtained by taking the rocket core body coordinate system as the moving reference system, and the velocity and angular velocity of the booster are discretely solved by using the secondary development module of the aerodynamic simulation solver, including: taking the rocket core body coordinate system as the moving reference system, the booster moves relative to the core stage, and the booster mass center is regarded as a moving point and the booster mass m ZT , obtaining the inertia term of the booster dynamics equation in the non-inertial system The velocity and angular velocity of the booster are discretely solved by using the improved Euler formula or the fourth-order Runge-Kutta method in the secondary development module of the aerodynamic simulation solver, and the velocity and angular velocity of the booster are obtained.

[0018] The velocity and angular velocity of the booster are discretely solved by using the improved Euler formula or the fourth-order Runge-Kutta method in the secondary development module of the aerodynamic simulation solver, and the velocity and angular velocity of the booster are obtained, including:

[0019] The aerodynamic force obtained by surface integration of a single booster and the aerodynamic moment The booster engine thrust and the thrust moment The side rocket thrust and the thrust moment The relative acceleration of the booster in the moving system is solved and the angular acceleration The booster motion differential equation is:

[0020]

[0021]

[0022] The improved Euler formula is used to solve the above booster motion differential equation, the booster mass and moment of inertia are set, and the velocity angular velocity

[0023]

[0024]

[0025] In the formula: m ZT is the mass of the booster; I ZT is the moment of inertia matrix of the booster; is the acceleration vector of the booster mass center in the moving system; is the angular acceleration vector of the booster mass center in the moving system; h is the time step.

[0026] The setting aerodynamic simulation turbulence model and solution format comprises: the aerodynamic simulation adopts a standard k-e turbulence model and a Simple solution format.

[0027] Inertial force terms of the fluid mechanics momentum equation in the non-inertial system are obtained according to the atmospheric environment density ρ of the rocket in the boost separation process, taking the rocket core body coordinate system as a dynamic reference system The inertial force terms are added in the form of momentum equation source terms in the extension module of the aerodynamic simulation solver.

[0028] The rocket boost separation dynamic aerodynamic simulation method has the advantages that: the simulation model takes the rocket core body coordinate system as a dynamic reference system, the inertial terms of the boost vehicle dynamics equation and the inertial terms of the fluid mechanics momentum equation in the non-inertial system are obtained by using the rocket core flight acceleration, the motion parameters of the boost vehicle center of mass and the time-varying flow field data in the boost separation process are solved by using a numerical algorithm and an aerodynamic simulation solver respectively, rich aerodynamic data support is provided for rocket boost separation scheme analysis and rocket body load design, and the aerodynamic force interpolation deviation problem existing in the prior boost separation trajectory calculation is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a flowchart of the rocket boost separation dynamic aerodynamic simulation method.

[0030] Figure 2 It is a rocket model of the embodiment of the present application.

[0031] Figure 3 It is an aerodynamic load curve of the rocket core level measuring point obtained by the embodiment of the present application. DETAILED DESCRIPTION

[0032] The present application will be further described in detail below in combination with the drawings and embodiments.

[0033] According to the present application, the rocket boost separation dynamic aerodynamic simulation is realized by adopting the following technical scheme:

[0034] The present application discloses a rocket boost separation dynamic aerodynamic simulation method, which is an improvement and expansion of the original boost vehicle static aerodynamic simulation and separation trajectory calculation.

[0035] Step 1: according to the rocket aerodynamic shape, an aerodynamic simulation model before boost separation is established, as shown in Figure 2 The object in the embodiment is a solid-liquid bundled rocket, the rocket core level adopts 2 liquid engines, 4 boosters each adopt 1 solid engine, and a pair of side thrust rockets are arranged at the head and tail of the boosters;

[0036] Step 2, the dynamic mesh method used in the dynamic aerodynamic simulation of the boost separation in this embodiment is the mesh reconstruction method, the process is as follows: according to the geometric characteristics of the aerodynamic simulation model, four spinners are used to wrap four boosters respectively, so that the fluid domain of the aerodynamic simulation model is divided into five parts, which are the background domain containing the rocket core stage and four moving domains wrapping the boosters; the unstructured mesh of the aerodynamic simulation model is generated, the local area rich in flow field details is meshed, and the wall boundary layer is set on the surface of the rocket core stage and the boosters; during the calculation, the motion parameters of the boosters are assigned to the moving domains wrapping the boosters, the internal mesh of the moving domains follows the rigid motion of the boosters, and the mesh reconstruction is completed in the background domain mesh;

[0037] Step 3, the obtained simulation mesh is imported into the aerodynamic simulation solver, and according to the actual flight state of the rocket, the incoming flow pressure, velocity, temperature of the simulation model, and the inlet total pressure and total temperature of each engine are set;

[0038] Step 4, the standard k-e turbulence model and the Simple solution format are used in the aerodynamic simulation;

[0039] Step 5, in this embodiment, the flight acceleration of the rocket core stage is Taking the rocket core stage body coordinate system as the dynamic reference system, the inertia force term of the booster dynamics equation in the non-inertial system is Combined with the aerodynamic force and the aerodynamic moment of a single booster, the engine thrust and the thrust moment of the side thrust rocket and the thrust moment , the booster dynamics equation in the non-inertial system is obtained:

[0040]

[0041]

[0042] In the formula: m ZT is the mass of the booster; I ZT is the moment of inertia matrix of the booster; is the mass center acceleration vector of the booster in the non-inertial system; is the mass center angular acceleration vector of the booster in the non-inertial system;

[0043] In the secondary development module of the aerodynamic solver, the improved Euler formula is used to discretely solve the velocity and the angular velocity of the booster in the non-inertial system, and the specific formula is:

[0044]

[0045]

[0046] In the formula: Respectively, the booster speed, angular velocity in the non-inertial system; The lower indexes n and n+1 respectively indicate the previous time and the current time; H is the time step.

[0047] Step 6, taking the rocket core stage body coordinate system as a dynamic reference system, according to the atmospheric environment density ρ of the rocket in the boost separation process, the inertial force term of the fluid mechanics momentum equation in the non-inertial system is obtained The source term is added in the extension module of the aerodynamic simulation solver, so as to correct the momentum equation of the aerodynamic simulation solver;

[0048] Step 7, on the basis of steps 3-6, the time step h=0.002s is selected, the unsteady dynamic aerodynamic simulation is carried out, the center of mass displacement, speed, acceleration, angle, angular velocity, angular acceleration of the booster are dynamically output, and the flow field pressure, temperature and aerodynamic load of the rocket body are extracted from the simulation results, as shown in Figure 3

[0049] The motion data of the center of mass of the booster obtained by the application can be used for analyzing the safety and reliability of the boost separation, and the aerodynamic load data of the rocket surface measuring point obtained by the application can be used for guiding the rocket load design.​

Claims

1. A method for dynamic aerodynamic simulation of rocket boost separation, characterized in that, The application relates to a method for establishing a dynamic aerodynamic simulation model of a full rocket before booster separation. The method comprises the following steps: establishing a full rocket aerodynamic simulation model according to a rocket aerodynamic shape; determining a dynamic mesh method for the dynamic aerodynamic simulation of the booster separation, dividing the obtained full rocket aerodynamic simulation model into topologies and generating simulation meshes; introducing the obtained simulation meshes into an aerodynamic simulation solver and completing boundary condition setting; the boundary conditions include the flow velocity, pressure, temperature of the full rocket simulation model and the total pressure and total temperature of the inlets of the engines; setting a turbulence model and a solution format in the aerodynamic simulation solver; taking the body coordinate system of the rocket core stage as a dynamic reference system, obtaining the inertia force term of the booster dynamics equation in a non-inertial system, and discretely solving the velocity and angular velocity of the booster by using a secondary development module of the aerodynamic simulation solver; taking the body coordinate system of the rocket core stage as a dynamic reference system, obtaining the inertia force term of the fluid mechanics momentum equation in a non-inertial system, and adding the inertia force term in the form of a momentum equation source term in an extended module of the aerodynamic simulation solver; based on the aerodynamic simulation setting and the booster motion solving setting, selecting a time step, performing unsteady dynamic aerodynamic simulation, and outputting the booster mass center displacement, velocity, acceleration, angle, angular velocity and angular acceleration in real time, and extracting the flow field pressure, temperature and rocket body aerodynamic load from the simulation results.

2. The method of claim 1, wherein: The method for establishing the dynamic aerodynamic simulation of the booster separation specifically adopts a grid reconstruction method, and the process is as follows: according to the geometric characteristics of the aerodynamic simulation model, four spin bodies are adopted to respectively wrap four boosters, so that the fluid domain of the aerodynamic simulation model is divided into five parts, namely a background domain containing the rocket core stage and four motion domains wrapping the boosters; non-structured meshes of the aerodynamic simulation model are generated, the local areas rich in flow field details are subjected to grid densification, and wall boundary layers are arranged on the surfaces of the rocket core stage and the boosters; during the calculation process, the motion parameters of the boosters are given to the motion domains wrapping the boosters, the internal meshes of the motion domains follow the rigid motion of the boosters, and the grid reconstruction is completed in the background domain meshes.

3. The method of claim 1, wherein: According to the boost separation process, the velocity vector of the rocket core stage flight is set The velocity vector of the inflow of the simulation model is set It refers to taking the rocket core stage body coordinate system as the moving system, keeping the inflow boundary of the simulation model still, and setting the velocity vector of the inflow boundary in the moving system.

4. The method of claim 1, wherein: The inertia force term of the booster dynamics equation in the non-inertial system is obtained by taking the rocket core body coordinate system as a dynamic reference system, and the velocity and angular velocity of the booster are discretely solved by using a secondary development module of an aerodynamic simulation solver, including: taking the rocket core body coordinate system as a dynamic reference system, the booster moves relative to the core stage, and the booster center of mass is regarded as a dynamic point and the booster mass m ZT , obtaining the inertia term of the booster dynamics equation in the non-inertial system The velocity and angular velocity of the booster are discretely solved by using an improved Euler formula or a fourth-order Runge-Kutta method in the secondary development module of the aerodynamic simulation solver, and the velocity and angular velocity of the booster are obtained.

5. The method of dynamic aerodynamic simulation of a rocket boost separation according to claim 4, characterized in that: the velocity and angular velocity of the boosters are discretely solved by using an improved Euler formula or a fourth-order Runge-Kutta method in the secondary development module of the aerodynamic simulation solver, and the velocity and angular velocity of the boosters are obtained, including: Aerodynamic forces and moments from individual booster surface integrals Aerodynamic forces and moments from individual booster surface integrals Booster engine thrust forces and moments Booster engine thrust forces and moments Side rocket thrust forces and moments Side rocket thrust forces and moments Solving for the relative acceleration of the boosters in the moving reference frame Solving for the relative acceleration of the boosters in the moving reference frame The boost motion differential equations are: The improved Euler formula is used to solve the above differential equation of the boost movement, and the mass and moment of inertia of the booster are set to calculate the velocity of the booster at the next time angular velocity where: m ZT is the booster mass; I ZT is the moment of inertia matrix of the booster; is the acceleration vector of the booster's center of mass in the moving frame; is the angular acceleration vector of the booster's center of mass in the moving frame; h is the time step.

6. The method of claim 1, wherein: the method for setting the turbulence model and the solution format of the aerodynamic simulation comprises the following steps: the aerodynamic simulation adopts a standard k-e turbulence model and a Simple solution format.

7. The method of claim 1, wherein: According to the density of atmosphere ρ in which the rocket is located during the boost-separation process, the inertial force term of the fluid mechanics momentum equation in the non-inertial system is obtained with the rocket core stage body coordinate system as the moving reference system The inertial force term is added in the form of a momentum equation source term in the extension module of the aerodynamic simulation solver.

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