| Radar technology research has always been the focus of research in the field of defense.Since Robert Wortson Watt invented the first radar in 1935,it has been more than 80 years of research history.During this period,a large number of R&D personnel and funds were invested in various military powers.The data contained in the radar echo is continuously excavated,and it is hoped that the radar target will be more aware of the electromagnetic characteristics that can better reflect the target.At present,the acquisition of electromagnetic characteristics of static targets is very mature,and the theoretical prediction ability can replace the actual measurement in a large range,improving efficiency and saving costs.However,the real target in motion is usually quite different from static.In addition to the simple Doppler effect introduced by translation,the target local fretting may be accompanied by very rich radar features.Especially in high-speed motion,aeroelasticity causes the target to produce flutter deformation.According to the actual measurement,the radar echo of the target is significantly deviated from the static state,and the electromagnetic characteristics cannot be obtained simply by electromagnetic multi-state analysis.The existing research usually assumes that the edge of the aircraft wing is tilted.This paper intends to study the influence of the fretting,especially the wing flutter on the target radar scattering characteristics,based on strict fluid,structure and electromagnetic joint simulation.The specific work is as follows:(1)The electromagnetic scattering characteristics of the fretting target are studied.Based on the study of radar cross section(RCS)and angular glint,the effects of the rotation of the helicopter rotor,the precession of the gyro,the sinusoidal vibration of the ball on the RCS and angular glint,and the Doppler shift in micro-motion process are studied.(2)The electromagnetic scattering characteristics of the flutter target were studied.According to the characteristics of the target geometric deformation compared with the extremely slow transmission speed of the electric wave,the electromagnetic scattering characteristics of the flutter target are modeled by the fluid,structure and electromagnetic loose coupling modeling.The paper analyzes the aerodynamic performance of the target by means of fluid-structure coupling,and studies the effects of factors such as lift coefficient and drag coefficient during high-speed flight.The electromagnetic simulation and time-frequency analysis of geometric model sequences compares multi-velocity steady-state and static.The electromagnetic scattering characteristics of the target’s RCS and angular glint are analyzed.Finally,the RCS and angular glint changes during uniform acceleration and the micro-Doppler shift due to aircraft flutter are analyzed. |
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