低升阻比飞行器月球返回再入轨迹特性分析

Trajectory characteristics analysis of low lift-drag-ratio vehicle for lunar return entry

月球返回再入轨迹特性与低地球轨道再入轨迹特性具有鲜明的不同,为研究此问题,推导建立了再入问题的数学模型并进行了飞行仿真试验,然后对比分析了低升阻比飞行器月球返回再入的轨迹特性.仿真实验表明,再入角对纵程、热流和过载影响显著,较小的再入角能够改善热流和过载环境;倾侧角翻转对纵程、热流和过载均无明显影响,但对横程影响显著,为纵侧向解耦制导提供了依据;最大峰值热流总是出现在一次峰值过载之前,且随着再入速度减小呈明显减小趋势.据此,再入飞行器在初始下降段实现充分有效的减速后迅速跃出大气,可以改善热流环境.

The trajectory characteristics of lunar return reentry are determined by cosmic velocity dynamics. The model of reentry problem is established. Based on the trajectory characteristics analysis of lunar return reentry, we obtained the following conclusions. First, entry angle has a significant effect on downrange, heating rate and g-load. A small entry angle can significantly improve heating and g-load environment. Second, bank reversal has no significant effect on downrange, heating rate and g-load, but has a significant effect on cross-range, which provides a basis for the vertical and lateral decoupling guidance. Third, the maximum heating rate always appears before the first peak g-load, and decreases with the decreasing of entry velocity. Thus, it requires the vehicle to achieve decelerating adequately and effectively in the initial descent phase and then skip out of the atmosphere to improve the heating environment.