飞船返回舱再入稀薄流域配平特性研究

Research on Trim Features of Reentry Capsule in Hypersonic Rarefied Flow Regime

飞船返回舱一般采用横偏质心位置的方法来提供再入配平攻角和实现飞行轨迹机动控制所需的配平升阻比,准确预测配平攻角随再入高度的变化对控制系统以及返回舱落点精度都非常重要。中国载人飞船返回舱再入稀薄流域配平攻角地面试验、理论计算和实际飞行中有较大差异,如何分析评估将直接影响到其它深空探测返回器的气动设计。文章采用工程和数值方法,在对原有风洞试验数据和理论计算数据整理分析的基础上,结合"阿波罗"返回舱的部分试验结果和计算研究结果以及"联盟号"飞船返回舱的计算结果,给出了配平攻角沿再入轨道变化的基本规律,分析了质心位置、壁面反射模型、马赫数、高温真实气体效应等影响返回舱再入配平特性的主要因素,可以对未来近似外形的试验和计算研究提供参考。

A center-of-gravity vertical offset is generally adopted for reentry capsules to provide trim angle of attack and lift-to-drag ratio required for manoeuvrable control of flight trajectory. It is extremely important for control system and capsule landing precision to accurately predict the variation of trim angle with altitude. For manned reentry capsules of our nation, the trim angles of attack in hypersonic rarefied flow regime differ significantly among ground experiments, theoretical computations and flight activities. How to analyze and assess those results will directly impact on the aerodynamic design of other return capsules for deep space explorations. This paper gives the fundamental rules for the variation of trim angle along reentry trajectories, analyzes the main factors of trim feature, such as the barycenter position, surface reflection model, Mach number and high temperature real gas effect, and provides references for future ground experiment and computation of trim features for similar shapes. The analysis uses both engineering and numerical methods, based on the original wind tunnel experimental data and theoretical computation results, and combines with partial test data and computation results of Apollo Command Module as well as the computation results of Soyuz reentry capsule.