固体火箭尾焰雷达散射截面数值计算

Numerical Calculation of Radar Cross-Section of Solid Rocket Exhaust Plume

固体火箭含铝复合推进剂含有较多的碱金属杂质,铝与碱金属在推进剂的燃烧过程中发生电离,燃气中存在较多的自由电子,经喷管喷出,形成等离子体尾焰,严重干扰测控信号与箭体之间的信号传输,以4种工况的固体火箭发动机尾焰流场计算结果为基础,建立了尾焰等离子体模型,使用矩量法计算当测控信号电磁波频率小于尾焰等离子体振荡频率时,对应4种工况的火箭雷达散射截面,分析了固体火箭尾焰对不同频率测控信号的干扰影响。结果表明:尾焰的存在增加了目标雷达散射截面,干扰了测控信号的有效传输;随着测控信号电磁波频率的增加,干扰作用减小;随着Al2O3含量增加,干扰作用增加;高空环境相比地面环境,干扰作用减小。

The solid rocket with aluminized propellant contains many alkali metal elements impurities, aluminum and alkali metal ionize in the combustion process of the propellant, and produces lots of free electrons in the gas, which are ejected from the nozzle to form the plasma exhaust plume. The plasma model of exhaust plume is established on the basis of the calculated results of the exhaust plume flow field of the solid rocket motor under four working conditions. When the electromagnetic wave frequency of the radar signal is less than the plasma oscillation frequency of the exhaust plume, the radar cross-section of the rocket radar corresponding to four working conditions is calculated by using the method of moments, and the influence of solid rocket exhaust plume on the interference at different frequency signals is analyzed. The results show that the existence of exhaust plume increases the radar cross-section and interferes with the effective transmission of the signals. With the increase of electromagnetic wave frequency, the interference effect decreases, the interference effect increases with the increase of Al2 O3 content, and the interference effect decreases when the high altitude environment is compared with the ground environment.