A numerical simulation-based launch vehicle core stage pulsating pressure prediction method and system

Abstract

The present application relates to a kind of based on numerical simulation launch vehicle core stage fluctuating pressure prediction method and system, the method comprises: obtaining the fluctuating pressure characteristics of inertial system along the bus of rocket model;Obtain the fluctuating pressure characteristics of non-inertial system along the bus of rocket model;Obtain the correction coefficient of rocket accelerated flight;Correct the fluctuating pressure characteristics of inertial system simulation under the maximum resultant angle of attack;The method can give full play to the advantage of numerical simulation in the selection optimization phase of launch vehicle, or in the case of canceling fluctuating pressure wind tunnel test, efficiently and reliably complete launch vehicle fluctuating pressure parameter design, adapt to the demand of model.

Description

Technical Field

[0001] This invention relates to a method and system for predicting the pulsating pressure of a launch vehicle core stage based on numerical simulation, belonging to the field of aerodynamic simulation technology. Background Technology

[0002] As the launch vehicle ascends within the atmosphere, transient airflow impacts the spacecraft structure. Pressure pulsations on the walls significantly affect the dynamic loads on the spacecraft structure, causing overall rocket bending vibration, fairing breathing vibration, and local structural swaying. The impact loads create a noise environment inside the rocket; if the noise environment is not clearly identified, sensors may fail.

[0003] In the overall design of launch vehicles, the aspects closely coupled with the pressure pulsation of the spacecraft include: 1) identifying potential buffeting phenomena, quantifying the dynamic load envelope, and supporting the structural strength, stiffness, and fatigue design of the spacecraft; 2) identifying the noise environment and supporting the vibration and noise reduction design of the rocket's internal instruments and meters. Therefore, accurately quantifying the pressure pulsation of the launch vehicle during its ascent in the atmosphere is a key aspect of the overall rocket design.

[0004] Traditionally, the acquisition of transonic fluctuating pressure parameters for launch vehicles has primarily relied on fluctuating pressure wind tunnel tests. While wind tunnel tests offer high reliability and a short testing cycle after model fabrication, they require supplementation with simulation methods in the following aspects: 1) During the modification and optimization phase, the rocket fairing shape undergoes repeated changes, necessitating repeated fabrication of the rocket model, resulting in large scale, high cost, and long cycle; 2) Wind tunnel walls can cause interference, potentially leading to peaks in the fluctuating pressure power spectrum that affect dynamic load calculations; 3) The rocket's acceleration in the transonic range can only be achieved through variable Mach number fluctuating pressure wind tunnels, which are large-scale and expensive.

[0005] Accordingly, numerical simulation has the following advantages: 1) During the modification and optimization stage, simulation can be achieved through modeling to address the repeated changes in the shape of the rocket fairing, which is efficient and has a short cycle; 2) The boundary conditions of the simulation can directly adopt the far-field boundary. After applying the non-reflection boundary condition, the boundary effect will not affect the power spectral density of the pulsating pressure, and the problem of cavity wall interference is effectively solved. How to give full play to the advantages of numerical simulation and efficiently complete the design of the pulsating pressure parameters of the launch vehicle has become an urgent problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned defects of the prior art and provide a method and system for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation. In the launch vehicle selection and optimization stage, or when the pulsating pressure wind tunnel test is cancelled, the advantages of numerical simulation can be fully utilized to efficiently and reliably complete the design of the pulsating pressure parameters of the launch vehicle and meet the requirements of the model.

[0007] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions:

[0008] A method for predicting the pulsating pressure of a launch vehicle core stage based on numerical simulation includes:

[0009] A scaled-down model of the rocket is modeled, and the pulsating pressure in the inertial frame is numerically simulated according to the typical state of the transonic range. The pulsating pressure characteristics along the generatrix of the rocket model in the inertial frame are statistically obtained. The pulsating pressure characteristics include the root mean square pulsating pressure coefficient and the pulsating pressure power spectral density.

[0010] Calculate the average acceleration of the rocket in the transonic range, construct a non-inertial frame of the rocket scaled-down model based on the average acceleration, add the volume force term of the momentum equation introduced by the non-inertial frame and the volume force work term of the total energy equation introduced by the non-inertial frame according to the compressible gas control equation set, and obtain the compressible gas control equation set in the non-inertial frame.

[0011] Numerical simulation of pulsating pressure in acceleration state is performed on a scaled-down rocket model based on the control equations for compressible gas in the non-inertial frame. The zero angle of attack state is calculated, and the pulsating pressure characteristics along the generatrix of the rocket model in the non-inertial frame are statistically obtained. The pulsating pressure characteristics include the root mean square pulsating pressure coefficient and the pulsating pressure power spectral density.

[0012] Based on the rocket's average acceleration, the time t at which the typical state of the inertial frame simulation appears in the non-inertial frame simulation is calculated. The pulsating pressure characteristics along the rocket model generatrix in the non-inertial frame at time t are extracted. The root mean square pulsating pressure coefficient along the rocket model generatrix in the non-inertial frame at time t is divided by the root mean square pulsating pressure coefficient along the rocket model generatrix in the corresponding inertial frame to obtain the correction coefficient for the rocket's accelerated flight.

[0013] The root mean square pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack are corrected using the aforementioned correction coefficients.

[0014] In the aforementioned method for predicting the pulsating pressure of a launch vehicle core stage based on numerical simulation, the addition of a volume force term to the momentum equation introduced by a non-inertial frame of reference, and a volume force work term to the total energy equation introduced by a non-inertial frame of reference, based on the compressible gas governing equations, includes:

[0015] The governing equations for compressible gases are as follows:

[0016]

[0017]

[0018]

[0019] Where - and ~ represent the filtered average and the Favre filtered average, respectively, t is time, ρ is density, u is velocity, p is pressure, and τ is... e For equivalent shear stress, e t Let h be the total energy, and h be the enthalpy. t Let ζ be the total enthalpy, ζ be the heat flux, and D be the total enthalpy. T The turbulent diffusion coefficient;

[0020] The volume force term in the momentum equation, introduced by a non-inertial frame of reference, is added as follows:

[0021]

[0022] Where 'a' represents the rocket's average acceleration in the transonic range. For the scaled-down rocket model, l o For the original dimensions of the rocket, l r The scale for a scaled-down model of a rocket;

[0023] The work done by body forces in the total energy equation, introduced by a non-inertial frame of reference, is as follows:

[0024]

[0025] In the above-mentioned method for predicting the pulsating pressure of a launch vehicle core stage based on numerical simulation, the step of calculating the occurrence time t of the typical state in the inertial frame simulation in the non-inertial frame simulation based on the rocket's average acceleration includes:

[0026]

[0027] Where t is the moment when the typical state appears in the non-inertial frame simulation, Ma is the Mach number of the typical state, c is the speed of sound of the typical state, and u0 is the initial velocity of the non-inertial frame simulation.

[0028] In the above-mentioned method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation, the step of dividing the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the non-inertial frame by the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the corresponding inertial frame to obtain the correction coefficient for rocket acceleration includes:

[0029] ξ(X;Ma)=cp i,rms (X;Ma,α=0) / cp n,rms (X;Ma,α=0)

[0030] Where ξ is the correction factor for rocket acceleration, X is the coordinate, α is the angle of attack, and cp is the y-axis. i,rms The root mean square pulsating pressure coefficient for inertial frame simulation, cp n,rms The root mean square pulsating pressure coefficient is used for simulation in non-inertial frames.

[0031] In the above-mentioned method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation, the step of correcting the root mean square pulsating pressure coefficient of the inertial frame simulation at the maximum combined angle of attack using a correction coefficient includes:

[0032] cp n,rms (X;Ma,α max )=ξ(X;Ma)·cp i,rms (X;Ma,α max )

[0033] Among them, cp i,rms (X;Ma,α max ) represents the root mean square pulsating pressure coefficient of the inertial frame simulation at the maximum composite angle of attack; cp n,rms (X;Ma,α max α is the root mean square pulsating pressure coefficient in the non-inertial frame simulation at the maximum composite angle of attack; Ma is the Mach number in the typical state; X is the coordinate; α is the root mean square pulsating pressure coefficient. max This represents the maximum composite angle of attack.

[0034] In the above-mentioned method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation, the step of correcting the root mean square pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack using correction coefficients includes:

[0035] S n (X,ω;Ma,α max )=[ξ(X;Ma)] 2 ·S i (X,ω;Ma,α max )

[0036] Among them, S i (X,ω;Ma,α max S represents the power spectral density of the inertial frame simulation at the maximum composite angle of attack. n (X,ω;Ma,α max ω represents the power spectral density in the non-inertial frame simulation at the maximum combined angle of attack; Ma is the Mach number in the typical state; X is the coordinate; and α is the frequency of the power spectral density. max This represents the maximum composite angle of attack.

[0037] The aforementioned method for predicting core stage pulsating pressure of a launch vehicle based on numerical simulation also includes, based on the modified root mean square pulsating pressure coefficient and pulsating pressure power spectral density at the maximum combined angle of attack, a ground-to-ground equivalent conversion is performed according to the scaled-down rocket model, serving as a reference for the design of rocket dynamic loads.

[0038] cp n,o,rms (X;Ma,α max ) = cp n,rms (X;Ma,αmax )

[0039]

[0040] Among them, cp n,o,rms (X;Ma,α max S represents the root mean square pulsating pressure coefficient at the rocket's original dimensions under the maximum synthetic angle of attack. n,o (X,ω;Ma,α max q represents the pulsating pressure power spectral density at the rocket's original scale under the maximum synthetic angle of attack. o Let q be the dynamic pressure at the moment when the rocket is flying at Mach number Ma. r The dynamic pressure is simulated for an inertial frame with Mach number Ma.

[0041] A numerical simulation-based system for predicting core stage pulsating pressure in launch vehicles includes:

[0042] The first simulation statistics module models a scaled-down rocket model and performs numerical simulation of pulsating pressure in the inertial frame based on typical conditions in the transonic range. It statistically obtains the pulsating pressure characteristics along the generatrix of the rocket model in the inertial frame, including the pulsating pressure coefficient and the pulsating pressure power spectral density.

[0043] The second simulation and statistics module calculates the average acceleration of the rocket across the sound range. Using this average acceleration, a non-inertial frame is constructed for the scaled-down rocket model. Based on the compressible gas control equations, a volume force term is added to the momentum equation introduced by the non-inertial frame, and a volume force work term is added to the total energy equation introduced by the non-inertial frame, thus obtaining the compressible gas control equations in the non-inertial frame. Based on these equations, a numerical simulation of the pulsating pressure under acceleration conditions is performed on the scaled-down rocket model. The zero angle-of-attack state is calculated, and the pulsating pressure characteristics along the generatrix of the rocket model in the non-inertial frame are statistically obtained. These pulsating pressure characteristics include the pulsating pressure coefficient and the pulsating pressure power spectral density.

[0044] The correction coefficient acquisition module calculates the time t when the typical state of the inertial frame simulation appears in the non-inertial frame simulation based on the rocket's average acceleration, extracts the pulsating pressure characteristics of the rocket model generatrix along the lower edge of the non-inertial frame at time t, and divides the pulsating pressure coefficient of the rocket model generatrix along the lower edge of the non-inertial frame at time t with the pulsating pressure coefficient of the corresponding rocket model generatrix along the lower edge of the inertial frame to obtain the correction coefficient for the rocket's accelerated flight.

[0045] The correction module uses the correction coefficient to correct the root mean square pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum synthetic angle of attack.

[0046] In the aforementioned numerical simulation-based prediction system for the pulsating pressure of a launch vehicle core stage, the second simulation statistics module, based on the compressible gas governing equations, adds a volume force term to the momentum equation introduced by a non-inertial frame of reference, and adds a volume force work term to the total energy equation introduced by a non-inertial frame of reference, including:

[0047] The governing equations for compressible gases are as follows:

[0048]

[0049]

[0050]

[0051] Where - and ~ represent the filtered average and Favre filtered average, respectively; t is time; ρ is density; u is velocity; p is pressure; and τ is... e For equivalent shear stress, e t Let h be the total energy, and h be the enthalpy. t Let ζ be the total enthalpy, ζ be the heat flux, and D be the total enthalpy. T The turbulent diffusion coefficient;

[0052] The volume force term in the momentum equation, introduced by a non-inertial frame of reference, is added as follows:

[0053]

[0054] Where 'a' represents the rocket's average acceleration in the transonic range. For the scaled-down rocket model, l o For the original dimensions of the rocket, l r The scale for a scaled-down model of a rocket;

[0055] The work done by body forces in the total energy equation, introduced by a non-inertial frame of reference, is as follows:

[0056]

[0057] In the aforementioned numerical simulation-based system for predicting the pulsating pressure of a launch vehicle core stage, the correction coefficient acquisition module calculates the occurrence time tt of the typical state in the inertial frame simulation in the non-inertial frame simulation based on the rocket's average acceleration, including:

[0058]

[0059] Where t is the moment when the typical state appears in the non-inertial frame simulation, Ma is the Mach number of the typical state, c is the speed of sound in the typical state, and u0 is the initial velocity of the non-inertial frame simulation.

[0060] Compared with the prior art, the present invention has at least the following beneficial effects:

[0061] This invention proposes a method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation. In the launch vehicle selection and optimization stage, or when the pulsating pressure wind tunnel test is cancelled, the advantages of numerical simulation can be fully utilized to efficiently and reliably complete the design of the pulsating pressure parameters of the launch vehicle, so as to meet the requirements of the model. Attached Figure Description

[0062] Figure 1 This is a flowchart of the method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation, as described in this invention.

[0063] Figure 2 This is a pressure contour map for the simulation of variable Mach number in a non-inertial frame of reference in this invention. Detailed Implementation

[0064] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0065] This invention discloses a numerical simulation-based technology for predicting the pulsating pressure of a launch vehicle core stage. The simulation is divided into two parts: inertial frame simulation and non-inertial frame simulation.

[0066] In the inertial frame simulation process, the maximum angle of attack and wind angle of attack in the transonic band are first obtained based on the rocket trajectory, and the maximum combined angle of attack in the transonic band is calculated. Then, a scaled-down model of the rocket is modeled. Based on the typical state in the transonic band and the compressible gas control equations, a high-fidelity flux scheme and a wall-adaptive large eddy simulation turbulence model (known in the art) are used to conduct numerical simulation of pulsating pressure on the scaled-down rocket model. The zero angle of attack and the maximum combined angle of attack are calculated, and the root mean square pulsating pressure coefficient and pulsating pressure power spectral density along the generatrix of the rocket model are statistically obtained (common knowledge in the art).

[0067] In the non-inertial frame simulation step, the average acceleration of the rocket in the transonic range is first calculated based on the rocket's flight trajectory, and the non-inertial frame of the rocket model is constructed using this acceleration. Subsequently, based on the compressible gas governing equations, the volume force term of the momentum equation introduced by the non-inertial frame is added, and the volume force work term of the total energy equation is added. Based on a high-fidelity numerical scheme and wall-adaptive large eddy simulation, a numerical simulation of the pulsating pressure in the acceleration state is carried out for the scaled-down rocket model. The zero angle of attack state is calculated, and the root mean square pulsating pressure coefficient and pulsating pressure power spectral density along the generatrix of the rocket model are statistically obtained.

[0068] After obtaining the statistical results of the pulsating pressure from both inertial and non-inertial frame simulations, the occurrence time of the typical state in the inertial frame simulation is first calculated based on the rocket's average acceleration. Then, the pulsating pressure simulation result of the non-inertial frame simulation at that moment is extracted, and its root mean square (RMS) pulsating pressure coefficient along the rocket's generatrix is ​​divided by the corresponding RMS pulsating pressure coefficient along the rocket's generatrix in the inertial frame simulation to obtain the correction coefficient for the rocket's accelerated flight. This correction is applied to the RMS pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack. Finally, based on the corrected RMS pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack, a ground-to-ground consistency equivalent conversion is performed according to the scaled-down rocket model (a well-known technique in the field, see the patent specification for details), predicting the RMS pulsating pressure coefficient and pulsating pressure power spectral density of the rocket in flight, serving as a reference for the rocket's dynamic load design.

[0069] like Figure 1 The diagram shows the flowchart of the method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation, according to the present invention. The specific method includes the following steps:

[0070] Step 1: Model a scaled-down rocket model and perform numerical simulation of pulsating pressure in the inertial frame based on the typical state of the transonic range. Statistically obtain the pulsating pressure characteristics along the generatrix of the rocket model in the inertial frame. The pulsating pressure characteristics include the root mean square pulsating pressure coefficient and the pulsating pressure power spectral density.

[0071] Step 2: In the non-inertial frame simulation step, firstly, based on the rocket's flight trajectory, calculate the rocket's average acceleration in the transonic range. Construct the non-inertial frame of the rocket model using this acceleration. Then, based on the compressible gas governing equations (which describe the laws governing flow in the non-inertial frame), add the volume force term of the momentum equation introduced by the non-inertial frame, and add the volume force work term of the total energy equation introduced by the non-inertial frame, to obtain the compressible gas governing equations in the non-inertial frame.

[0072] The governing equations for compressible gases are as follows:

[0073]

[0074]

[0075]

[0076] Where - and ~ represent the filtered average and Favre filtered average, respectively; t is time; ρ is density; u is velocity; p is pressure; and τ is... e For equivalent shear stress, e t Let h be the total energy, and h be the enthalpy. t Let ζ be the total enthalpy, ζ be the heat flux, and D be the total enthalpy. TThe turbulent diffusion coefficient;

[0077] The volume force term in the momentum equation, introduced by a non-inertial frame of reference, is added as follows:

[0078]

[0079] Where 'a' represents the rocket's average acceleration in the transonic range. For the scaled-down rocket model, l o For the original dimensions of the rocket, l r The scale for a scaled-down model of a rocket;

[0080] The work done by body forces in the total energy equation, introduced by a non-inertial frame of reference, is as follows:

[0081]

[0082] Step 3: Based on the high-fidelity numerical format and wall-adaptive large eddy simulation, the pulsating pressure of the rocket scaled-down model under acceleration is numerically simulated according to the compressible gas control equations in the non-inertial frame. The zero angle of attack state is calculated, and the pulsating pressure characteristics along the generatrix of the rocket model in the non-inertial frame are statistically obtained. The pulsating pressure characteristics include the root mean square pulsating pressure coefficient and the pulsating pressure power spectral density.

[0083] Step 4: Based on the rocket's average acceleration, calculate the time t at which the typical state of the inertial frame simulation occurs in the non-inertial frame simulation. Extract the pulsating pressure characteristics of the rocket model generatrix along the lower edge of the non-inertial frame at time t. Divide the root mean square pulsating pressure coefficient of the rocket model generatrix along the lower edge of the non-inertial frame at time t by the root mean square pulsating pressure coefficient of the corresponding rocket model generatrix along the lower edge of the inertial frame to obtain the correction coefficient for the rocket's accelerated flight.

[0084] After obtaining the statistical results of the pulsating pressure from both inertial and non-inertial frame simulations, the occurrence times of typical states in the inertial frame simulation are first calculated based on the rocket's average acceleration.

[0085]

[0086] Where t is the moment when the typical state appears in the non-inertial frame simulation, Ma is the Mach number of the typical state, c is the speed of sound of the typical state, and u0 is the initial velocity of the non-inertial frame simulation.

[0087] Dividing the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the non-inertial frame by the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the corresponding inertial frame yields the correction coefficients for rocket acceleration, including:

[0088] ξ(X;Ma)=cp i,rms (X;Ma,α=0) / cp n,rms(X;Ma,α=0)

[0089] Where ξ is the correction factor for rocket acceleration, X is the coordinate, α is the angle of attack, and cp is the y-axis. i,rms The root mean square pulsating pressure coefficient for inertial frame simulation, cp n,rms The root mean square pulsating pressure coefficient is used for simulation in non-inertial frames.

[0090] Step 5: Use the above correction coefficients to correct the root mean square pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack.

[0091] The root mean square pulsating pressure coefficient of the inertial frame simulation at the maximum combined angle of attack is corrected using correction factors, including:

[0092] cp n,rms (X;Ma,α max )=ξ(X;Ma)·cp i,rms (X;Ma,α max )

[0093] Among them, cp i,rms (X;Ma,α max ) represents the root mean square pulsating pressure coefficient of the inertial frame simulation at the maximum composite angle of attack; cp n,rms (X;Ma,α max α is the root mean square pulsating pressure coefficient in the non-inertial frame simulation at the maximum composite angle of attack; Ma is the Mach number in the typical state; X is the coordinate; α is the root mean square pulsating pressure coefficient. max This represents the maximum composite angle of attack.

[0094] The root mean square pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack is corrected using correction factors, including:

[0095] S n (X,ω;Ma,α max )=[ξ(X;Ma)] 2 ·S i (X,ω;Ma,α max )

[0096] Among them, S i (X,ω;Ma,α max S represents the power spectral density of the inertial frame simulation at the maximum composite angle of attack. n (X,ω;Ma,α max ω represents the power spectral density in the non-inertial frame simulation at the maximum combined angle of attack; Ma is the Mach number in the typical state; X is the coordinate; and α is the frequency of the power spectral density. max This is the maximum combined angle of attack. For example... Figure 2 The figure shown is a pressure contour plot of the non-inertial frame of the present invention with varying Mach number simulation.

[0097] Finally, based on the corrected root mean square pulsating pressure coefficient and pulsating pressure power spectral density at the maximum synthetic angle of attack, a ground-to-ground consistency equivalent conversion is performed according to the scaled-down rocket model:

[0098] cp n,o,rms (X;Ma,α max ) = cp n,rms (X;Ma,α max )

[0099]

[0100] Among them, cp n,o,rms (X;Ma,α max S represents the root mean square pulsating pressure coefficient at the rocket's original dimensions under the maximum synthetic angle of attack. n,o (X,ω;Ma,α max q represents the pulsating pressure power spectral density at the rocket's original scale under the maximum synthetic angle of attack. o Let q be the dynamic pressure at the moment when the rocket is flying at Mach number Ma. r The dynamic pressure is simulated for an inertial frame with Mach number Ma.

[0101] The root mean square pulsating pressure coefficient and pulsating pressure power spectral density at the rocket's original scale are used as references for the design of rocket dynamic loads.

[0102] This invention also provides a numerical simulation-based system for predicting core stage pulsating pressure in launch vehicles, comprising:

[0103] The first simulation statistics module models a scaled-down rocket model and performs numerical simulation of pulsating pressure in the inertial frame based on typical conditions in the transonic range. It statistically obtains the pulsating pressure characteristics along the generatrix of the rocket model in the inertial frame, including the root mean square pulsating pressure coefficient and the pulsating pressure power spectral density.

[0104] The second simulation and statistics module calculates the average acceleration of the rocket across the sound range. Using this average acceleration, a non-inertial frame is constructed for the scaled-down rocket model. Based on the compressible gas control equations, a volume force term is added to the momentum equation introduced by the non-inertial frame, and a volume force work term is added to the total energy equation introduced by the non-inertial frame, thus obtaining the compressible gas control equations in the non-inertial frame. Based on these equations, a numerical simulation of the pulsating pressure under acceleration conditions is performed on the scaled-down rocket model. The zero angle-of-attack state is calculated, and the pulsating pressure characteristics along the generatrix of the rocket model in the non-inertial frame are statistically obtained. These pulsating pressure characteristics include the pulsating pressure coefficient and the pulsating pressure power spectral density.

[0105] The correction coefficient acquisition module calculates the time t when the typical state of the inertial frame simulation appears in the non-inertial frame simulation based on the rocket's average acceleration, extracts the pulsating pressure characteristics along the generatrix of the rocket model in the non-inertial frame at time t, and divides the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the non-inertial frame at time t by the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the corresponding inertial frame to obtain the correction coefficient for the rocket's accelerated flight.

[0106] The correction module uses the correction coefficient to correct the root mean square pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum synthetic angle of attack.

[0107] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0108] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for predicting the pulsating pressure of a launch vehicle core stage based on numerical simulation, characterized in that, include: A scaled-down model of the rocket is modeled, and the pulsating pressure in the inertial frame is numerically simulated according to the typical state of the transonic range. The pulsating pressure characteristics along the generatrix of the rocket model in the inertial frame are statistically obtained. The pulsating pressure characteristics include the root mean square pulsating pressure coefficient and the pulsating pressure power spectral density. Calculate the average acceleration of the rocket in the transonic range, construct a non-inertial frame of the rocket scaled-down model based on the average acceleration, add the volume force term of the momentum equation introduced by the non-inertial frame and the volume force work term of the total energy equation introduced by the non-inertial frame according to the compressible gas control equation set, and obtain the compressible gas control equation set in the non-inertial frame. Numerical simulation of pulsating pressure in acceleration state is performed on a scaled-down rocket model based on the control equations for compressible gas in the non-inertial frame. The zero angle of attack state is calculated, and the pulsating pressure characteristics along the generatrix of the rocket model in the non-inertial frame are statistically obtained. The pulsating pressure characteristics include the root mean square pulsating pressure coefficient and the pulsating pressure power spectral density. Based on the rocket's average acceleration, the time t at which the typical state of the inertial frame simulation appears in the non-inertial frame simulation is calculated. The pulsating pressure characteristics along the rocket model generatrix in the non-inertial frame at time t are extracted. The root mean square pulsating pressure coefficient along the rocket model generatrix in the non-inertial frame at time t is divided by the root mean square pulsating pressure coefficient along the rocket model generatrix in the corresponding inertial frame to obtain the correction coefficient for the rocket's accelerated flight. The root mean square pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack are corrected using the aforementioned correction coefficients.

2. The method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation according to claim 1, characterized in that, The addition of a volume force term to the momentum equation introduced by a non-inertial frame of reference, and a volume force work term to the total energy equation introduced by a non-inertial frame of reference, based on the governing equations for compressible gases, includes: The governing equations for compressible gases are as follows: Where - and ~ represent the filtered average and the Favre filtered average, respectively, t is time, ρ is density, u is velocity, p is pressure, and τ is... e For equivalent shear stress, e t Let h be the total energy, and h be the enthalpy. t For total enthalpy, For heat flux, D T The turbulent diffusion coefficient; The volume force term in the momentum equation, introduced by a non-inertial frame of reference, is added as follows: Where 'a' represents the rocket's average acceleration in the transonic range. For the scaled-down rocket model, l o For the original dimensions of the rocket, l r The scale for a scaled-down model of a rocket; The work done by body forces in the total energy equation, introduced by a non-inertial frame of reference, is as follows:

3. The method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation according to claim 1, characterized in that, The calculation of the time t at which the typical state in the inertial frame simulation occurs in the non-inertial frame simulation based on the rocket's average acceleration includes: Where t is the moment when the typical state appears in the non-inertial frame simulation, Ma is the Mach number of the typical state, c is the speed of sound of the typical state, and u0 is the initial velocity of the non-inertial frame simulation.

4. The method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation according to claim 1, characterized in that, The step of dividing the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the non-inertial frame by the root mean square pulsating pressure coefficient along the generatrix of the rocket model in the corresponding inertial frame to obtain the correction coefficient for rocket acceleration includes: ξ(X;Ma)=cp i，rms (X;Ma,α=0) / cp n，rms (X;Ma,α=0) Where ξ is the correction factor for rocket acceleration, X is the coordinate, α is the angle of attack, and cp is the y-axis. i，rms The root mean square pulsating pressure coefficient for inertial frame simulation, cp n，rms The root mean square pulsating pressure coefficient is used for simulation in a non-inertial frame.

5. The method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation according to claim 4, characterized in that, The method of correcting the root mean square pulsating pressure coefficient of the inertial frame simulation at the maximum combined angle of attack using correction coefficients includes: cp n，rms (X;Ma,α max )=ξ(X;Ma)·cp i，rms (X;Ma,α max ) Among them, cp i，ms (X;Ma,α max ) represents the root mean square pulsating pressure coefficient of the inertial frame simulation at the maximum composite angle of attack; cp n，ms (X;Ma,α max α is the root mean square pulsating pressure coefficient in the non-inertial frame simulation at the maximum composite angle of attack; Ma is the Mach number in the typical state; X is the coordinate; α is the root mean square pulsating pressure coefficient. max This represents the maximum composite angle of attack.

6. The method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation according to claim 4, characterized in that, The method of correcting the root mean square pulsating pressure power spectral density of the inertial frame simulation at the maximum combined angle of attack using correction coefficients includes: S n (X,ω;Ma,α max )=[ξ(X;Ma)] 2 ·S i (X,ω;Ma,α max ) Among them, S i (X, ω; Ma, α) max S represents the power spectral density of the inertial frame simulation at the maximum combined angle of attack. n (X, ω; Ma, α) max ω represents the power spectral density in the non-inertial frame simulation at the maximum combined angle of attack; Ma is the Mach number in the typical state; X is the coordinate; and α is the frequency of the power spectral density. max This represents the maximum composite angle of attack.

7. The method for predicting the core stage pulsating pressure of a launch vehicle based on numerical simulation according to claim 1, characterized in that, It also includes, based on the modified root mean square pulsating pressure coefficient and pulsating pressure power spectral density at the maximum synthetic angle of attack, a ground-to-ground equivalent conversion is performed according to the scaled-down rocket model, serving as a reference for the design of rocket dynamic loads: cp n，o，rms (X;Ma,α max )=cp n，rms (X;Ma,α max ) Among them, cp n，o，rms (X;Ma,α max S represents the root mean square pulsating pressure coefficient at the rocket's original dimensions under the maximum synthetic angle of attack. n，o (X, ω; Ma, α) max q represents the pulsating pressure power spectral density at the rocket's original scale under the maximum synthetic angle of attack. o Let q be the dynamic pressure at the moment when the rocket is flying at Mach number Ma. r The dynamic pressure is simulated for an inertial frame with Mach number Ma.

8. A launch vehicle core stage pulsating pressure prediction system based on numerical simulation, characterized in that, include: The first simulation statistics module models a scaled-down rocket model and performs numerical simulation of pulsating pressure in the inertial frame based on typical conditions in the transonic range. It statistically obtains the pulsating pressure characteristics along the generatrix of the rocket model in the inertial frame, including the pulsating pressure coefficient and the pulsating pressure power spectral density. The second simulation statistics module calculates the average acceleration of the rocket across the sound speed range. It constructs a non-inertial frame for a scaled-down model of the rocket based on the average acceleration. According to the compressible gas control equations, it adds the volume force term of the momentum equation introduced by the non-inertial frame and the volume force work term of the total energy equation introduced by the non-inertial frame to obtain the compressible gas control equations in the non-inertial frame. Numerical simulation of pulsating pressure in acceleration state is performed on a scaled-down rocket model based on the control equations for compressible gas in the non-inertial frame. The zero angle of attack state is calculated, and the pulsating pressure characteristics along the generatrix of the rocket model in the non-inertial frame are statistically obtained. The pulsating pressure characteristics include the pulsating pressure coefficient and the pulsating pressure power spectral density. The correction coefficient acquisition module calculates the time t when the typical state of the inertial frame simulation appears in the non-inertial frame simulation based on the rocket's average acceleration, extracts the pulsating pressure characteristics of the rocket model generatrix along the lower edge of the non-inertial frame at time t, and divides the pulsating pressure coefficient of the rocket model generatrix along the lower edge of the non-inertial frame at time t with the pulsating pressure coefficient of the corresponding rocket model generatrix along the lower edge of the inertial frame to obtain the correction coefficient for the rocket's accelerated flight. The correction module uses the correction coefficient to correct the root mean square pulsating pressure coefficient and pulsating pressure power spectral density of the inertial frame simulation at the maximum synthetic angle of attack.

9. The launch vehicle core stage pulsating pressure prediction system based on numerical simulation according to claim 8, characterized in that, The second simulation statistics module, based on the compressible gas governing equations, adds a volume force term to the momentum equation introduced by a non-inertial frame of reference, and a volume force work term to the total energy equation introduced by a non-inertial frame of reference, including: The governing equations for compressible gases are as follows: Where - and ~ represent the filtered average and Favre filtered average, respectively; t is time; ρ is density; u is velocity; p is pressure; and τ is... e For equivalent shear stress, e t Let h be the total energy, and h be the enthalpy. t For total enthalpy, For heat flux, D T The turbulent diffusion coefficient; The volume force term in the momentum equation, introduced by a non-inertial frame of reference, is added as follows: Where 'a' represents the rocket's average acceleration in the transonic range. For the scaled-down rocket model, l o For the original dimensions of the rocket, l r The scale for a scaled-down model of a rocket; The work done by body forces in the total energy equation, introduced by a non-inertial frame of reference, is as follows:

10. The launch vehicle core stage pulsating pressure prediction system based on numerical simulation according to claim 8, characterized in that, The correction coefficient acquisition module calculates the occurrence time tt of the typical state in the inertial frame simulation in the non-inertial frame simulation based on the rocket's average acceleration, including: Where t is the moment when the typical state appears in the non-inertial frame simulation, Ma is the Mach number of the typical state, c is the speed of sound of the typical state, and u0 is the initial velocity of the non-inertial frame simulation.

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