再入钝锥体绕流流场电磁散射特性分析

Analysis of Scattering for the Flow Field of Reentry Blunted Cone

采用分段线性电流密度递归卷积时域有限差分(PLJERC-FDTD)方法计算再入钝锥体绕流流场电磁散射特性,分析钝锥体等离子体包覆绕流流场的RCS频率特性、极化特性及双站散射特性。计算表明,在马赫数较小(本文Ma≤10)时,马赫数变化对绕流流场后向RCS影响较小。电磁波垂直锥体母线入射时,极化方式(本文极化角0°和90°)改变对绕流流场后向RCS影响较小;绕流流场后向RCS随入射波频率变化曲线可用两条直线来逼近;随入射波频率增大,绕流流场后向RCS振荡上增。前向散射是全方位散射中RCS取得最大值的方向;入射角大于钝锥半锥角时,除前向RCS外,以锥体母线为基准的镜面反射方向RCS比其它散射方向RCS大。

A piecewise linear current density （JE） recursive convolution finite-difference time-domain （PLJERC-FDTD） algorithm is applied to the study of the scattering for the flow field of reentry object. The effects of incidence wave frequency, polarization angle and scattering angle on the radar cross section （RCS） have been obtained. The results illustrate that the backward RCS of flow fields varies very small with the Mach number within 10 at this article. The margin of backward RCS between polarization angle 0 degree and 90 degree is small, the curve of backward RCS varies with incidence wave frequency can be approached by two lines, and the backward RCS increases with incidence wave frequency as a whole when the incidence direction of electromagnetic wave is perpendicular to the cone generatrix. The forward RCS is the maximal RCS of all scattering orientation. The RCS of mirror reflection orientation in reference to the cone generatrix is bigger than the RCS of other scattering angles, except for the forward RCS, when the incidence angle is larger than semi-cone angle.