RCS Estimation Of The Hypersonic Aircraft Based On Time Domain And Chaff Cover Analysis

In recent years,the focus of people's research has gradually been shifted from low altitude and space to near-space.What is active in near-space is undoubtedly the hypersonic vehicle.Compared with the ordinary aircraft,it has the characteristics of extremely high flying altitude,fast flight speed and powerful lateral mobility,which makes it have significant strategic meaning and high military application value.In the near future,the hypersonic vehicle as a new type of non-nuclear strategic deterrence is highly likely to break the existing military pattern.Therefore,the research on the hypersonic vehicle is particularly vital.The thesis first researches the flight path of the hypersonic vehicle and finds that the hypersonic vehicle may face the risk of being intercepted at the inertial phase.Since the environment of the inertial phase is same as that of the intermediate stage of ballistic trajectory,the author will use space chaff to cover the hypersonic vehicle and analyze it,and simulate radar to estimate its broadband RCS before covering it.The thesis systematically studies the flight path of the hypersonic vehicle and the motion characteristics and scattering properties of space chaff cloud.Aiming at aspects of time-domain high-frequency electromagnetic scattering algorithm adopted by the hypersonic vehicle,the effect of Doppler shift on target identification caused by the speed of the hypersonic vehicle and chaff cloud covering the hypersonic vehicle,the main work and contribution of this thesis are as follows:1.The study firstly introduces the flight path of the hypersonic vehicle,based on which its characteristics at each stage of the flight path are explored and the risk of interception by missiles at the inertial phase is found.In view of this risk,the thesis employs space chaff to cover and analyze the hypersonic vehicle.2.Broadband RCS estimation of the hypersonic vehicle is studied in depth.Take X-43 A hypersonic vehicle model as an example.The hybrid algorithm combining TDPO with TDSBR is used to analyze it.Firstly,TDPO solution based on Radon transform is introduced,and its simulation experiments are carried out to verify the correctness and efficiency of the algorithm.Then TDSBR algorithm is presented and a series of improvements are made.The results of simulation experiments show that the algorithm is efficient and accurate.Nevertheless,the cavity engine in the hypersonic vehicle results in imprecision of TDPO and time-consuming problem of TDSBR.Therefore,in order to solve those problems,the hybrid method of TDPO and TDSBR is put forward.And incident wave is used to judge whether the cavity is illuminated.If it is illuminated,TDSBR will be used for cavity calculation and TDPO will be employed to calculate fuselage.If not,the whole plane will be calculated by TDPO.The author uses cuboid slices to improve the efficiency of the algorithm.Finally,a series of simulation comparison experiments with X-43 A model are conducted to verify the correctness and efficiency of the algorithm.3.The motion diffusion features of space chaff cloud on the basis of free molecular flow are researched in the thesis.The study firstly carries out the force analysis of the single chaff in the atmospheric environment at the inertial stage of the hypersonic vehicle.Then Monte Carlo method is used to extend the single chaff to chaff cloud.Based on the theory,a series of simulation experiments are conducted.4.The radar scattering characteristics of chaff cloud are studied in the thesis.Firstly,two distinct forms of moment method are used to explore the radar scattering properties of the single chaff and an optimal method is obtained through comparative analyses.Ignoring coupling effect between the chaff,the author obtains the radar cross section of chaff cloud via superposing the scattering field vector of each chaff in chaff cloud and carries out a series of simulation experiments.5.Electromagnetic wave emitted by radar has Doppler frequency shift between the hypersonic vehicle at high speed and radar,which leads to the impact on broadband RCS estimation of the hypersonic vehicle.And the HV(X-43 A model)at the inertial stage80-120 Km is analyzed,when the fixed early warning radar is at the attack point.The author modifies it to broadband RCS estimation of the hypersonic vehicle and obtains the standard value of chaff covering which takes X-43 A model as an example.Finally,X-band radar adopting distinct amounts of chaff at different heights is simulated to analyze chaff covering of the hypersonic vehicle.