Boundary layer transition(BLT)can cause a sharp rise in heat flux and skin friction,which can seriously affect the flight performance and safety of hypersonic flight vehicles.Therefore,the mechanism,prediction and con...Boundary layer transition(BLT)can cause a sharp rise in heat flux and skin friction,which can seriously affect the flight performance and safety of hypersonic flight vehicles.Therefore,the mechanism,prediction and control of transition have become important issues that must be dealt with for the development of advanced flight vehicles,and it is also a research hotspot of particular interest to major aerospace countries.Compared to other transition research approaches,model flight tests can better present the transition problems under real flight conditions,thus have been carried out extensively over the past 30 years.The United States,Germany,France,Australia,and other countries have carried out transition research based on flight tests,such as the Pegasus wing-glove crossflow transition and the Hypersonic Boundary Layer Transition(HyBOLT)transition control flight test of the United States,the joint research project of the Hypersonic International Flight Research and Experimentation-1(HIFiRE-1)circular cone and the HIFiRE-5 elliptic cone transition flight tests between the United States and Australia,the flight test of compression surface transition of the scramjet forebody(LEA)in France and so on.Although these flight tests suffered various setbacks,they still obtained valuable transition data.Recently,the United States is carrying out the concave-surface transition flight tests of Hypersonic Boundary Layer Transition(BOLT)and BOLT-II.Since its first model flight test mission for verification purpose launched successfully in 2015,several hypersonic BLT flight tests have been conducted by China Aerodynamics Research and Development Center(CARDC).The flight tests have measured valid transition data under flight conditions,obtained the transition front and its dynamical variation on blunt cones at various angles of attack and a lifting body Hypersonic Transition Research Vehicle(HyTRV).The crossflow traveling waves in high-altitude flight were measured for the first time,and our understanding of hypersonic BLT has been greatly improved.展开更多
Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters.In this work,the arc ablation behaviors and mechanisms of commercial CuCr10,CuCr25,and CuCr50 cathodes were i...Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters.In this work,the arc ablation behaviors and mechanisms of commercial CuCr10,CuCr25,and CuCr50 cathodes were investigated for pure copper and pure chromium cathodes.The discharging homogeneity was improved with the increase of chromium content in the cathodes,which was attributed to the formed chromic oxide layer.The CuCr50 cathodes exhibited the lowest ablation rate with a reduction of 27.0%compared to the copper cathodes.The chromic oxide formed in the pit protected the bottom matrix,leading to a homogeneous ablation process.The mechanism for the improved homogeneous ablation behaviors of the CuCr50 cathodes was proposed and featured by the suppression of deep pits and the dispersion of arc foot.Future attention will be focused on designing composite cathodes with an anti-ablation surface layer and a good conductive matrix.展开更多
High-speed airflow in wind tunnel tests usually causes dramatic vibration of ejector structure,which may lead to fatigue and even destruction of the wind tunnel.Therefore,analyzing and solving the flow-induced vibrati...High-speed airflow in wind tunnel tests usually causes dramatic vibration of ejector structure,which may lead to fatigue and even destruction of the wind tunnel.Therefore,analyzing and solving the flow-induced vibration problem is a tough and indispensable part of the wind tunnel security design.In this paper,taking a kind of two-stage ejector as the study object,multiple numerical simulation methods are adopted in order to carry out research on the analysis technique of the flow-induced vibration characteristics of ejector structure.Firstly,the structural dynamics characteristic is analyzed by using the ejector structural dynamics numerical model,which is built on the basis of finite element method.Secondly,the complex flow phenomenon is explored applying numerical fluid-dynamics model of the inner flow field of the ejector,which is constructed on the basis of finite volume method.Finally,based on the two numerical models above,the vibration response of the ejector structure induced by the high-speed airflow is computed via the fluid-solid coupling technique.The comparison of the simulation results with the actual vibration test indicates that these numerical simulation methods can accurately figure out the rule of flow-induced vibration of ejectors.展开更多
A parameter estimation algorithm is introduced and used to determine the parameters in the standard k-epsilon two equation turbulence model (SKE). It can be found from the estimation results that although the paramete...A parameter estimation algorithm is introduced and used to determine the parameters in the standard k-epsilon two equation turbulence model (SKE). It can be found from the estimation results that although the parameter estimation method is an effective method to determine model parameters, it is. difficult to obtain a set of parameters for SKE to suit all kinds of separated flow and a modification of the turbulence model structure should be considered. So, a new nonlinear k-e two-equation model (NNKE) is put forward in this paper and the corresponding parameter estimation technique is applied to determine the model parameters. By implementing the NNKE to solve some engineering turbulent flows, it is shown that NNKE is more accurate and versatile than SKE. Thus, the success of NNKE implies that the parameter estimation technique may have a bright prospect in engineering turbulence model research.展开更多
A three-equation transition model based on the transition V-model is proposed for subsonic flows in this study. Considering the mechanical approximation of the generation process of the pre-transitional vorticities, t...A three-equation transition model based on the transition V-model is proposed for subsonic flows in this study. Considering the mechanical approximation of the generation process of the pre-transitional vorticities, the value of laminar Reynolds shear stress related to the mean shear deformation was calculated in the original transition V-model. Then a new transition model, named V-SA model, was proposed, which considered the phenomenological process of transition and presented great results for flows with and without pressure gradient. It is well-known that the baseline Shear Stress Transport(SST) turbulence model shows excellent performance of accuracy and robustness in plentiful flow cases, but it is important to predict boundary layer transition. The current model(V-SST) successfully couples the V-model to the SST turbulence model by introducing the effective turbulent viscosity and additional correction terms into the transport equations. A thorough evaluation of its ability to predict transition features is performed versus the well-documented flat plate of ERCOFTAC, including T3A and T3B without pressure gradient, T3L2 and T3L3 with semi-circular leading edge, the three-dimensional 6:1 prolate-spheroid under two angles of attack, and the NLR-7301 airfoil under different Mach numbers. Numerical results show that the current model has an attractive and superior performance in the simulation of boundary layer transition processes.展开更多
At supercritical conditions a porous strip （or slot strip） placed beneath a shock wave can reduce the drag by a weaker lambda shock system, and increase the buffet boundary, even may increase the lift. Passive shock...At supercritical conditions a porous strip （or slot strip） placed beneath a shock wave can reduce the drag by a weaker lambda shock system, and increase the buffet boundary, even may increase the lift. Passive shock wave/boundary layer control （PSBC） for drag reduction was conducted by SC（2）-0714 supercritical wing, with emphases on parameter of porous/slot and bump, such as porous distribution, hole diameter, cavity depth, porous direction and so on. A sequential quadratic programming （SQP） optimization method coupled with ad]oint method was adopted to achieve the optimized shape and position of the bumps. Computational fluid dynamics （CFD）, force test and oil test with half model all indicate that PSBC with porous, slot and bump generally reduce the drag by weaker lambda shock at supercritical conditions. According to wind tunnel test results for angle of attack of 2° at Mach number M = 0.8, the porous configuration with 6.21% porosity results in a drag reduction of 0.0002 and lift-drag ratio increase of 0.2, the small bump configuration results in a drag reduction of 0.0007 and lift-drag ratio increase of 0.3. Bump normally reduce drag at design point with shock wave position being accurately computed. If bump diverges from the position of shock wave, drag will not be easily reduced.展开更多
The unmanned combat aerial vehicle(UCAV)is a research hot issue in the world,and the situation assessment is an important part of it.To overcome shortcomings of the existing situation assessment methods,such as low ac...The unmanned combat aerial vehicle(UCAV)is a research hot issue in the world,and the situation assessment is an important part of it.To overcome shortcomings of the existing situation assessment methods,such as low accuracy and strong dependence on prior knowledge,a datadriven situation assessment method is proposed.The clustering and classification are combined,the former is used to mine situational knowledge,and the latter is used to realize rapid assessment.Angle evaluation factor and distance evaluation factor are proposed to transform multi-dimensional air combat information into two-dimensional features.A convolution success-history based adaptive differential evolution with linear population size reduc-tion-means(C-LSHADE-Means)algorithm is proposed.The convolutional pooling layer is used to compress the size of data and preserve the distribution characteristics.The LSHADE algorithm is used to initialize the center of the mean clustering,which over-comes the defect of initialization sensitivity.Comparing experi-ment with the seven clustering algorithms is done on the UCI data set,through four clustering indexes,and it proves that the method proposed in this paper has better clustering performance.A situation assessment model based on stacked autoen-coder and learning vector quantization(SAE-LVQ)network is constructed,and it uses SAE to reconstruct air combat data fea-tures,and uses the self-competition layer of the LVQ to achieve efficient classification.Compared with the five kinds of assess-ments models,the SAE-LVQ model has the highest accuracy.Finally,three kinds of confrontation processes from air combat maneuvering instrumentation(ACMI)are selected,and the model in this paper is used for situation assessment.The assessment results are in line with the actual situation.展开更多
A proper orthogonal decomposition(POD)method is applied to the problem of a two-dimensional flow past two side-by-side circular cylinders.Based on the POD bases,which are constructed by a snapshot method,a low-dimensi...A proper orthogonal decomposition(POD)method is applied to the problem of a two-dimensional flow past two side-by-side circular cylinders.Based on the POD bases,which are constructed by a snapshot method,a low-dimensional model is established for representing two-dimensional incompressible Navier–Stokes equations.Coupled with the low-dimensional model,the Chiba method is used to analyze the global stability of the basic flow.Different bifurcation paths at three major regions are revealed,in good agreement with the available results by other methods.However,the computation amount in the POD method is low,which shows the availability and advantage of the POD method.展开更多
In the present paper,extremely unsteady shock wave buffet induced by strong shock wave/boundary-layer interactions (SWBLI) on the upper surface of an OAT15A supercritical airfoil at Mach number of 0.73 and angle of at...In the present paper,extremely unsteady shock wave buffet induced by strong shock wave/boundary-layer interactions (SWBLI) on the upper surface of an OAT15A supercritical airfoil at Mach number of 0.73 and angle of attack of 3.5 degrees is first numerically simulated by IDDES,one of the most advanced RANS/LES hybrid methods.The results imply that conventional URANS methods are unable to effectively predict the buffet phenomenon on the wing surface;IDDES,which involves more flow physics,predicted buffet phenomenon.Some complex flow phenomena are predicted and demonstrated,such as periodical oscillations of shock wave in the streamwise direction,strong shear layer detached from the shock wave due to SWBLI and plenty of small scale structures broken down by the shear layer instability and in the wake.The root mean square (RMS) of fluctuating pressure coefficients and streamwise range of shock wave oscillation reasonably agree with experimental data.Then,two vortex generators (VG) both with an inclination angle of 30 degrees to the main flow directions are mounted in front of the shock wave region on the upper surface to suppress shock wave buffet.The results show that shock wave buffet can be significantly suppressed by VGs,the RMS level of pressure in the buffet region is effectively reduced,and averaged shock wave position is obviously pushed downstream,resulting in increased total lift.展开更多
The copper cathode ablation limits the maximum power and operating time of arc heaters significantly.In this work,copper cathodes were tested in an ablation testing system to investigate the ablation behaviors and mec...The copper cathode ablation limits the maximum power and operating time of arc heaters significantly.In this work,copper cathodes were tested in an ablation testing system to investigate the ablation behaviors and mechanism of copper cathode in air.The microstructure of the ablated cathodes was analyzed,and the ablation rate was measured.The maximum depth and ablation rate increased with the electronic discharge.The mean ablation rate was compared with the prediction by a thermophysical theoretical model.Many ablation pits formed in the ablated surface and evolved into crater-like structures with unexpected depth as the ablation time was prolonged.The presence of ablation pits and crater-like structures suggested an inhomogeneous ablation behavior of the copper cathode in air.The underlying mechanism is proposed to explain the ablation failure of copper cathode in the high-power arc heater.Future attention to improving the service life of copper cathode could be focused on the surface modification to reduce the ablation inhomogeneity.展开更多
Large spacecraft fall out of orbit and re-enter the atmosphere at the end of their lifetime,and they can break up into small debris upon re-entry.The spacecraft debris generated by the disintegration may lead to high ...Large spacecraft fall out of orbit and re-enter the atmosphere at the end of their lifetime,and they can break up into small debris upon re-entry.The spacecraft debris generated by the disintegration may lead to high risk when the surviving debris reaches the ground.One way to reduce the damage risk of spacecraft is to simulate the spacecraft disintegration process and accurately predict the falling area.Aerodynamics seriously affects the reentering process,especially in the continuous flow regime.Aerodynamic force and heat are the main factors leading to debris disintegration.High dynamic pressure leads to sharp changes in attitude and complex trajectories during debris fall.A numerical method based on an unstructured Cartesian grid was developed to simulate the disintegrating separation problem by coupling the Navier-Stokes equation and the six-degree-of-freedom trajectory equation.A method combining the numerical method for dynamic processes with numerical simulation based on a static aerodynamic/dynamic characteristic database was developed for forecasting the falling area.Spacecraft disintegrating separation from 60 km was simulated using the method,and the multibody aerodynamic interference and the separation trajectory were predicted.The falling process was forecast by a numerical simulation method based on the static aerodynamic database/dynamic characteristic database when the debris went out of the influence domain.This method has good forecasting efficiency while considering the aerodynamic interference,making it a valuable method for forecasting disintegrating separation and falling debris.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grants 11772350,92052301).
文摘Boundary layer transition(BLT)can cause a sharp rise in heat flux and skin friction,which can seriously affect the flight performance and safety of hypersonic flight vehicles.Therefore,the mechanism,prediction and control of transition have become important issues that must be dealt with for the development of advanced flight vehicles,and it is also a research hotspot of particular interest to major aerospace countries.Compared to other transition research approaches,model flight tests can better present the transition problems under real flight conditions,thus have been carried out extensively over the past 30 years.The United States,Germany,France,Australia,and other countries have carried out transition research based on flight tests,such as the Pegasus wing-glove crossflow transition and the Hypersonic Boundary Layer Transition(HyBOLT)transition control flight test of the United States,the joint research project of the Hypersonic International Flight Research and Experimentation-1(HIFiRE-1)circular cone and the HIFiRE-5 elliptic cone transition flight tests between the United States and Australia,the flight test of compression surface transition of the scramjet forebody(LEA)in France and so on.Although these flight tests suffered various setbacks,they still obtained valuable transition data.Recently,the United States is carrying out the concave-surface transition flight tests of Hypersonic Boundary Layer Transition(BOLT)and BOLT-II.Since its first model flight test mission for verification purpose launched successfully in 2015,several hypersonic BLT flight tests have been conducted by China Aerodynamics Research and Development Center(CARDC).The flight tests have measured valid transition data under flight conditions,obtained the transition front and its dynamical variation on blunt cones at various angles of attack and a lifting body Hypersonic Transition Research Vehicle(HyTRV).The crossflow traveling waves in high-altitude flight were measured for the first time,and our understanding of hypersonic BLT has been greatly improved.
基金This work is financially supported by the National Key R&D Program of China(No.2017YFB1200800)the National Natural Science Foundation of China(Nos.11725210,11572281)the Fundamental Research Funds for the Central Universities(No.2018XZZX001-05)。
文摘Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters.In this work,the arc ablation behaviors and mechanisms of commercial CuCr10,CuCr25,and CuCr50 cathodes were investigated for pure copper and pure chromium cathodes.The discharging homogeneity was improved with the increase of chromium content in the cathodes,which was attributed to the formed chromic oxide layer.The CuCr50 cathodes exhibited the lowest ablation rate with a reduction of 27.0%compared to the copper cathodes.The chromic oxide formed in the pit protected the bottom matrix,leading to a homogeneous ablation process.The mechanism for the improved homogeneous ablation behaviors of the CuCr50 cathodes was proposed and featured by the suppression of deep pits and the dispersion of arc foot.Future attention will be focused on designing composite cathodes with an anti-ablation surface layer and a good conductive matrix.
基金supported in part by the National Natural Science Foundation of China (Nos.51806234, 51805530)
文摘High-speed airflow in wind tunnel tests usually causes dramatic vibration of ejector structure,which may lead to fatigue and even destruction of the wind tunnel.Therefore,analyzing and solving the flow-induced vibration problem is a tough and indispensable part of the wind tunnel security design.In this paper,taking a kind of two-stage ejector as the study object,multiple numerical simulation methods are adopted in order to carry out research on the analysis technique of the flow-induced vibration characteristics of ejector structure.Firstly,the structural dynamics characteristic is analyzed by using the ejector structural dynamics numerical model,which is built on the basis of finite element method.Secondly,the complex flow phenomenon is explored applying numerical fluid-dynamics model of the inner flow field of the ejector,which is constructed on the basis of finite volume method.Finally,based on the two numerical models above,the vibration response of the ejector structure induced by the high-speed airflow is computed via the fluid-solid coupling technique.The comparison of the simulation results with the actual vibration test indicates that these numerical simulation methods can accurately figure out the rule of flow-induced vibration of ejectors.
文摘A parameter estimation algorithm is introduced and used to determine the parameters in the standard k-epsilon two equation turbulence model (SKE). It can be found from the estimation results that although the parameter estimation method is an effective method to determine model parameters, it is. difficult to obtain a set of parameters for SKE to suit all kinds of separated flow and a modification of the turbulence model structure should be considered. So, a new nonlinear k-e two-equation model (NNKE) is put forward in this paper and the corresponding parameter estimation technique is applied to determine the model parameters. By implementing the NNKE to solve some engineering turbulent flows, it is shown that NNKE is more accurate and versatile than SKE. Thus, the success of NNKE implies that the parameter estimation technique may have a bright prospect in engineering turbulence model research.
基金supported by the National Natural Science Foundation of China(No.11721202)。
文摘A three-equation transition model based on the transition V-model is proposed for subsonic flows in this study. Considering the mechanical approximation of the generation process of the pre-transitional vorticities, the value of laminar Reynolds shear stress related to the mean shear deformation was calculated in the original transition V-model. Then a new transition model, named V-SA model, was proposed, which considered the phenomenological process of transition and presented great results for flows with and without pressure gradient. It is well-known that the baseline Shear Stress Transport(SST) turbulence model shows excellent performance of accuracy and robustness in plentiful flow cases, but it is important to predict boundary layer transition. The current model(V-SST) successfully couples the V-model to the SST turbulence model by introducing the effective turbulent viscosity and additional correction terms into the transport equations. A thorough evaluation of its ability to predict transition features is performed versus the well-documented flat plate of ERCOFTAC, including T3A and T3B without pressure gradient, T3L2 and T3L3 with semi-circular leading edge, the three-dimensional 6:1 prolate-spheroid under two angles of attack, and the NLR-7301 airfoil under different Mach numbers. Numerical results show that the current model has an attractive and superior performance in the simulation of boundary layer transition processes.
文摘At supercritical conditions a porous strip （or slot strip） placed beneath a shock wave can reduce the drag by a weaker lambda shock system, and increase the buffet boundary, even may increase the lift. Passive shock wave/boundary layer control （PSBC） for drag reduction was conducted by SC（2）-0714 supercritical wing, with emphases on parameter of porous/slot and bump, such as porous distribution, hole diameter, cavity depth, porous direction and so on. A sequential quadratic programming （SQP） optimization method coupled with ad]oint method was adopted to achieve the optimized shape and position of the bumps. Computational fluid dynamics （CFD）, force test and oil test with half model all indicate that PSBC with porous, slot and bump generally reduce the drag by weaker lambda shock at supercritical conditions. According to wind tunnel test results for angle of attack of 2° at Mach number M = 0.8, the porous configuration with 6.21% porosity results in a drag reduction of 0.0002 and lift-drag ratio increase of 0.2, the small bump configuration results in a drag reduction of 0.0007 and lift-drag ratio increase of 0.3. Bump normally reduce drag at design point with shock wave position being accurately computed. If bump diverges from the position of shock wave, drag will not be easily reduced.
基金supported by the Natural Science Foundation of Shaanxi Province(2020JQ-481,2021JM-224)the Aeronautical Science Foundation of China(201951096002).
文摘The unmanned combat aerial vehicle(UCAV)is a research hot issue in the world,and the situation assessment is an important part of it.To overcome shortcomings of the existing situation assessment methods,such as low accuracy and strong dependence on prior knowledge,a datadriven situation assessment method is proposed.The clustering and classification are combined,the former is used to mine situational knowledge,and the latter is used to realize rapid assessment.Angle evaluation factor and distance evaluation factor are proposed to transform multi-dimensional air combat information into two-dimensional features.A convolution success-history based adaptive differential evolution with linear population size reduc-tion-means(C-LSHADE-Means)algorithm is proposed.The convolutional pooling layer is used to compress the size of data and preserve the distribution characteristics.The LSHADE algorithm is used to initialize the center of the mean clustering,which over-comes the defect of initialization sensitivity.Comparing experi-ment with the seven clustering algorithms is done on the UCI data set,through four clustering indexes,and it proves that the method proposed in this paper has better clustering performance.A situation assessment model based on stacked autoen-coder and learning vector quantization(SAE-LVQ)network is constructed,and it uses SAE to reconstruct air combat data fea-tures,and uses the self-competition layer of the LVQ to achieve efficient classification.Compared with the five kinds of assess-ments models,the SAE-LVQ model has the highest accuracy.Finally,three kinds of confrontation processes from air combat maneuvering instrumentation(ACMI)are selected,and the model in this paper is used for situation assessment.The assessment results are in line with the actual situation.
基金Supported by the Research Foundation of SWUST(No 10zx7137)。
文摘A proper orthogonal decomposition(POD)method is applied to the problem of a two-dimensional flow past two side-by-side circular cylinders.Based on the POD bases,which are constructed by a snapshot method,a low-dimensional model is established for representing two-dimensional incompressible Navier–Stokes equations.Coupled with the low-dimensional model,the Chiba method is used to analyze the global stability of the basic flow.Different bifurcation paths at three major regions are revealed,in good agreement with the available results by other methods.However,the computation amount in the POD method is low,which shows the availability and advantage of the POD method.
基金supported by EU Project Advanced Turbulence Simulation for Aerodynamic Application Challenges (Grant No.ACP8-GA-2009-233710)the National Natural Science Foundation of China (Grant Nos.11072129 and 10932005)
文摘In the present paper,extremely unsteady shock wave buffet induced by strong shock wave/boundary-layer interactions (SWBLI) on the upper surface of an OAT15A supercritical airfoil at Mach number of 0.73 and angle of attack of 3.5 degrees is first numerically simulated by IDDES,one of the most advanced RANS/LES hybrid methods.The results imply that conventional URANS methods are unable to effectively predict the buffet phenomenon on the wing surface;IDDES,which involves more flow physics,predicted buffet phenomenon.Some complex flow phenomena are predicted and demonstrated,such as periodical oscillations of shock wave in the streamwise direction,strong shear layer detached from the shock wave due to SWBLI and plenty of small scale structures broken down by the shear layer instability and in the wake.The root mean square (RMS) of fluctuating pressure coefficients and streamwise range of shock wave oscillation reasonably agree with experimental data.Then,two vortex generators (VG) both with an inclination angle of 30 degrees to the main flow directions are mounted in front of the shock wave region on the upper surface to suppress shock wave buffet.The results show that shock wave buffet can be significantly suppressed by VGs,the RMS level of pressure in the buffet region is effectively reduced,and averaged shock wave position is obviously pushed downstream,resulting in increased total lift.
基金This work was supported by the National Key R&D Program of China(Grant No.2017YFB1200800)the National Natural Science Foundation of China(Grant Nos.11725210,51827810,51637009 and 11572281)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2018XZZX001-05)the National Student′s Platform for Innovation and Entrepreneurship Training Program(Grant No.201910335115).
文摘The copper cathode ablation limits the maximum power and operating time of arc heaters significantly.In this work,copper cathodes were tested in an ablation testing system to investigate the ablation behaviors and mechanism of copper cathode in air.The microstructure of the ablated cathodes was analyzed,and the ablation rate was measured.The maximum depth and ablation rate increased with the electronic discharge.The mean ablation rate was compared with the prediction by a thermophysical theoretical model.Many ablation pits formed in the ablated surface and evolved into crater-like structures with unexpected depth as the ablation time was prolonged.The presence of ablation pits and crater-like structures suggested an inhomogeneous ablation behavior of the copper cathode in air.The underlying mechanism is proposed to explain the ablation failure of copper cathode in the high-power arc heater.Future attention to improving the service life of copper cathode could be focused on the surface modification to reduce the ablation inhomogeneity.
基金supported by the National Basic Research Program of China under Grant Nos.2014CB744100,2022JCJQZD20600the Project of Manned Space Engineering Technology(Grant No.ZS2020103001).
文摘Large spacecraft fall out of orbit and re-enter the atmosphere at the end of their lifetime,and they can break up into small debris upon re-entry.The spacecraft debris generated by the disintegration may lead to high risk when the surviving debris reaches the ground.One way to reduce the damage risk of spacecraft is to simulate the spacecraft disintegration process and accurately predict the falling area.Aerodynamics seriously affects the reentering process,especially in the continuous flow regime.Aerodynamic force and heat are the main factors leading to debris disintegration.High dynamic pressure leads to sharp changes in attitude and complex trajectories during debris fall.A numerical method based on an unstructured Cartesian grid was developed to simulate the disintegrating separation problem by coupling the Navier-Stokes equation and the six-degree-of-freedom trajectory equation.A method combining the numerical method for dynamic processes with numerical simulation based on a static aerodynamic/dynamic characteristic database was developed for forecasting the falling area.Spacecraft disintegrating separation from 60 km was simulated using the method,and the multibody aerodynamic interference and the separation trajectory were predicted.The falling process was forecast by a numerical simulation method based on the static aerodynamic database/dynamic characteristic database when the debris went out of the influence domain.This method has good forecasting efficiency while considering the aerodynamic interference,making it a valuable method for forecasting disintegrating separation and falling debris.
