高真空羽流指空间目标上火箭发动机在高真空环境工作时产生的燃气射流迅速膨胀扩散流动状态。这种急剧膨胀的羽流会对空间目标产生冲击、侵蚀, 其产生的辐射特性已应用于空间目标的探测、识别。基于无碰撞的自由分子流理论模型对高真空羽流的流场进行了快速预测分析方法研究, 获得了高真空羽流的膨胀、扩散分布特性, 得到了符合认识的流动规律结果, 在计算得到高真空羽流流动参数的基础上, 采用佛奥特线型函数描述稀薄气体的展宽, 结合逐线积分法+视在光线法计算得到高真空羽流的辐射特性。研究结果表明: 高真空羽流的轮廓特性及扩散分布是由喷管出口的点源强度所决定的, 点源强度越强, 羽流扩散的越厉害, 同时轴线上无量纲的密度、温度越高; 喷管出口温度相同时, 高真空羽流辐射强度随点源增加而增强;出口速度相同时, 羽流辐射强度随点源增加而减小;在点源强度相同时, 羽流辐射强度与推力正相关。

When the rocket engine is working in high vacuum environment, the gas jet expands rapidly under the condition of extremely low back pressure, forming the vacuum plume. This vacuum plume can produce impact and erosion on space targets, and its infrared radiation characteristics can be widely used for the detection and recognition of the space targets. Based on the theoretical model of collisionless free molecular flow, the rapid analytical calculation of vacuum plume was carried out in this paper. The expansion and diffusion characteristics of the plume were obtained, which accorded with the known flow rule. On the basis of the calculated plume flow parameters, the Voigt line function was used to describe the dilating of the rarefied gas, and the radiation characteristics were calculated by line-by-line and LOS method. The results show that the boundary and diffusion distribution of vacuum plume are determined by the speed ratio of the nozzle exit. The stronger exit speed ratio is, the greater the area of the plume diffusions, and the higher the normalized density and temperature on the axis are. When the temperature of the nozzle exit is same, the radiation intensity of the plume increases with the increase of exit speed ratio. However, when the speed of the nozzle is same, the radiation intensity of the plume decreases with the increase of exit speed ratio. In the case of the same exit speed ratio, the radiation intensity is positively correlated with the thrust.