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Investigation of hypersonic flows through a cavity with sweepback angle in Near space using the DSMC method

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Chinese Physics B 2021年第7期30卷 311-323页

作者：郭广明陈浩朱林边义祥 College of Mechanical Engineering Yangzhou UniversityYangzhou 225127China

Near space has been paid more and more attentionin recent years due to its military application value.However,flow characteristics of some fundamental configurations(e.g.,the cavity)in Near space have rarely been investigated due to rarefied gas effects,which make the numerical simulation methods based on continuous flow hypothesis lose validity.In this work,the direct simulation Monte Carlo(DSMC),one of the most successful particle simulation methods in treating rarefied gas dynamics,is employed to explore flow characteristics of a hypersonic cavity with sweepback angle in Near space by considering a variety of cases,such as the cavity at a wide range of altitudes 20-60 km,the cavity at freestream Mach numbers of 6-20,and the cavity with a sweepback angle of 30°-90°.By analyzing the simulation results,flow characteristics are obtained and meanwhile some interesting phenomena are also found.The primary recirculation region,which occupies the most area of the cavity,causes pressure and temperature stratification due to rotational motion of fluid inside it,whereas the pressure and temperature in the secondary recirculation region,which is a small vortex and locates at the lower left corner of the cavity,change slightly due to low-speed movement of fluid inside it.With the increase of altitude,both the primary and secondary recirculation regions contract greatly and it causes them to separate.A notable finding is that rotation direction of the secondary recirculation region would be reversed at a higher altitude.The overall effect of increasing the Mach number is that the velocity,pressure,and temperature within the cavity increase uniformly.The maximum pressure nearby the trailing edge of the cavity decreases rapidly as the sweepback angle increases,whereas the influence of sweepback angle on velocity distribution and maximum temperature within the cavity is slight.

关键词： flow characteristics cavity with sweepback angle hypersonic flow Near space DSMC

Aerodynamic map for soft and hard hypersonic level flight in Near space

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Acta Mechanica Sinica 2009年第4期25卷 571-575页

作者： Ruifeng Hu Ziniu Wu Zhe Wu Xiaoxin Wang Zhongwei Tian School of Aerospace, Tsinghua University, 100084 Beijing, China School of Aerospace Tsinghua University Beijing China

In this note, we design a velocity-altitude map for hypersonic level flight in Near space of altitude 20-100 km. This map displays aerodynamic-related parameters associated with Near space level flight, schematically or quantitatively. Various physical conditions for the near-space level flight are then characterized, including laminar or turbulent flow, rarefaction or continuous flow, aerodynamic heating, as well as conditions for sustaining level flight with and without orbital effect. This map allows one to identify conditions to have soft flight or hard flight, and this identification would be helpful for making correct planning on detailed studies of aerodynamics or making initial design of Near space vehicles.

关键词： Near space Aerodynamics Hypersonic Level flight Soft flow

Configuration Method of the Dynamic Navigation Network Based on Near space

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Configuration Method of the Dynamic Navigation Network Based...

Preliminary Study on the Distribution of Meridional Wind in Near space

第九届中国卫星导航学术年会

作者： Lizhi Deng Yingkui Gong Hongxia Wan Bingcheng Liu University of Chinese Academy of Sciences Academy of opto-electronics Chinese Academy of Sciences

This paper focuses on the optimal design of the Near space navigation network configuration concerning a specific target area.Optimal design not only ensure navigation service for specific area with high accuracy and low cost;but also enable all users in the target area to obtain a controlled precision.In this design,a double-layer Y configuration is adopted as the optimal basic unit.Adaptive algorithm and genetic algorithm are selected to detect the boundary of the configuration to realize the synchronization optimization of cost and accuracy.Combining with the working principle of aerostat in the stratosphere airspace,we design a platform dynamic trajectory and provide an algorithm optimization of layout for the partial users’worse precision in dynamic scene.The simulation results show that the optimal design method proposed in this paper can meet the configuration design requirements of the dynamic navigation network based on Near space with different size area and different precision requirement.

关键词： Near space Intelligent algorithm Dynamic navigation network Aerostat

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Meteorological and Environmental Research 2015年第4期6卷 3-7页

作者： Chen Xiaojing Liu Xiaojia Shi Huiyan Chen Shuchi Sun Yu Beijing Aerospace Control Center Jiuquan Satellite Launch Center

Based on high-altitude wind data in about one year, the seasonal changes and vertical profiles of meridional wind in Near space were studied, and the reasons for the increase of meridional wind in spring and winter were analyzed. Meanwhile, the seasonal distribution of atmospher- ic circulation in the stratosphere was studied, and the seasonal changes and mechanism of wind conversion from the east to the west were re- vealed. The results show that the speed of meridional wind in Near space was the highest in spring, followed by autumn and winter, while it was the lowest in summer; the increase of meridional wind in spring and winter was related to weather systems in the troposphere, such as the development of strong warm ridge over Xinjianq and cold trouclh system, and the svstem resulted in the increase of meridional wind.

关键词： Near space Meddional wind Seasonal distribution China

Research on Near space Solar Cells Acquisition and Test System

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Research on Near Space Solar Cells Acquisition and Test Syst...

A New Optimal Guidance Law for Near space Hypersonic Vehicle Based on Markov Jump Linear System

第37届中国控制会议

作者： Guoning Xu Ying Miao Zhaojie Li Xiaowei Du Yang Gao Qianshi Liu Academy of Opto-Electronics Chinese Academy of Sciences

In this paper, a set of Near space solar cell accurate test system is designed. The system includes high-altitude scientific balloon, solar tracking mechanism and solar cell high-precision acquisition equipment. This paper solved the problem of high accuracy acquisition of solar tracking control system for high-altitude balloon solar cell test in extreme environment, Continuous tracking and anti-shake and other key technical issues. The paper achieved Near space I-V curve measurement for the first time, and the initial analysis of the system test results are reasonable, reliable and stable. The paper work provides a new idea and solution for our country Near space solar cells accurate measurement.

关键词： Near space high-altitude scientific balloon solar tracking I-V curve measurement

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A New Optimal Guidance Law for Near Space Hypersonic Vehicle...

Trajectory prediction in pipeline form for intercepting hypersonic gliding vehicles based on LSTM

2011 Chinese Control and Decision Conference（CCDC）

作者： HU Shi-guo is with the Air Force Engineering University of China,Xi''an,Shan''Xi 710038 China.FANG Yang-wang is with the Department of Aero Weaponry Engineering,Engineering college the Air Force Engineering University of china,Xi''an,Shan''Xi 710038 China.GAO Xiang is with the Air Force Engineering University of China,Xi''an,Shan''Xi 710038 China.

A new guidance law is proposed for Near space Hypersonic Vehicle （NSHV） based on multiple model theory and optimal control theory of structure stochastic jump system.By choosing different character velocities of the NSHV in Near space and aero space,different motion models for the NSHV of three-DOF are constructed.Then,for each model,a guidance law is developed by the proposed method.These guidance laws use the line-of-sight angular rate measurement information and only need the target’s maximum maneuverability.When targets maneuver at acceleration values less than the given maximum acceleration,the guide precision is independent of the variation of the acceleration.Simulation results indicate that the guidance laws could guide the NSHV precisely to the target in spite of the target maneuvers from Near space to aero space or within each space,with smooth trajectory and small over-load.

关键词： Near space Markov jump linear system optimal guidance law optimal filtering

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Chinese Journal of Aeronautics 2023年第5期36卷 421-433页

作者： Lihan SUN Baoqing YANG Jie MA Control and Simulation Center Harbin Institute of TechnologyHarbin 150040China

The interception problem of Hypersonic Gliding Vehicles(HGVs)has been an important aspect of missile defense systems.In order to provide interceptors with accurate information of target trajectory,a model based on an improved Long Short-Time Memory(LSTM)network for trajectory prediction pipeline is proposed for the interception of a skip gliding hypersonic target.Firstly,for trajectory prediction required by intercepting guidance laws,the altitude,velocity and velocity direction of the target are formulated in the form of analytic functions,consisting of linear decay terms and amplitude decay sinusoidal terms.Then,the dynamic characteristics of the model parameters are analyzed,and the target trajectory prediction pipeline is proposed with the prediction error considered.Finally,an improved LSTM network is designed to estimate parameters in a dynamically-updated manner,and estimation results are used for the calculation of the final trajectory prediction pipeline.The proposed prediction algorithm provides information on the velocity vector for midcourse guidance with the effect of prediction errors on interception taken into account.Simulation is conducted and the results show the high accuracy of the algorithm in HGVs’trajectory prediction which is conducive to increasing the interception success rate.

关键词： Hypersonic glide vehicles Long-short time memory Near space Skip glide Trajectory prediction

On-line trajectory generation of midcourse cooperative guidance for multiple interceptors

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Journal of Systems Engineering and Electronics 2022年第1期33卷 197-209页

作者： CHEN Wenyu SHAO Lei LEI Humin Air and Missile Defense College Air Force Engineering UniversityXi’an 710051China

The cooperative interception trajectories generation of multiple interceptors to hypersonic targets is studied.First,to solve the problem of on-line trajectory generation of the single interceptor,a generation method based on neighborhood optimal control is adopted.Then,when intercepting the strong maneuvering targets,the single interceptor is insufficient in maneuverability,therefore,an on-line multiple trajectories generation algorithm is proposed,which uses the multiple interceptors intercept area(IIA)to cover the target's predicted intercept area(PIA)cooperatively.Through optimizing the interceptors'zero control terminal location,the trajectories are generated on-line by using the neighborhood optimal control method,these trajectories could make the IIA maximally cover the PIA.The simulation results show that the proposed method can greatly improve the interception probability,which provides a reference for the collaborative interception of multiple interceptors.

关键词： cooperative interception trajectories generation Near space

Hypersonic Vehicle Trajectory Prediction Algorithm Based on Hough Transform

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Chinese Journal of Electronics 2021年第5期30卷 918-930页

作者： LI Fan XIONG Jiajun LAN Xuhui BI Hongkui TAN Xiansi Air Force Early Warning Academy Unit 95980 of the PLA

Trajectory prediction is a prerequisite for missile and high-speed vehicle guidance interception. To address the trajectory problem for the Near space hypersonic unpowered gliding vehicle. Firstly, the trajectory prediction mechanism is analyzed. Based on the existing NSHV trajectory prediction method, the key techniques of trajectory prediction are discussed from the perspectives of prediction parameter selection and prediction parameter description. Then, a trajectory prediction method based on Hough transform is proposed. The core of the method is to select the longitude latitude, and high direction positions as prediction parameters, and use the Hough transform to fit the prior basis functions. In the latitude and longitude direction, the rationality of predicting parameters is discussed from two aspects: position extreme point and lateral maneuverability. In the height direction,for the NSHV oscillation drop characteristic, two Hough transforms are used to separate the periodic term from the linear term. In addition, we give the approximate interval of the parameter values of the method, and design a parameter adaptive scheme. Finally, trajectory prediction is performed on two different control patterns. The error of the prediction time of 100 s is within 25 km, and the results show the effectiveness of the proposed method.

关键词： Neural nets (theory) Spatial variables control Aerospace control Integral transforms Control system analysis and synthesis methods Near space hypersonic vehicle trajectory prediction Hough transform