大型航天器无控再入气动稳定性分析

Analysis of Aerodynamic Stability During Large-scale Spacecraft Uncontrolled Re-entry

大型航天器在轨运行寿命终止后,为避免坠落在人口稠密地区造成事故,一般通过控制其主动离轨再入,使其坠落在南太平洋航天器坟场区域。再入大气层过程中受气动作用影响剧烈,航天器气动稳定性对再入姿态及姿态保持有直接影响,从而影响到再入轨道。为分析质心位置、航天器舱外部件等对航天器气动稳定性的影响,文章利用快速气动力方法,获得了航天器在不同工况下的气动力矩特性,进而分析其气动稳定性。对于给定质心位置的航天器,随着舱外部件不断解体,从单配平点转变为多配平点。而对于不同质心位置,质心位置接近端面时仅存在单配平点,位于中部则可能出现多配平点。因此,对于需要再入的大型航天器,其质心位置及舱外部件在设计阶段就应考虑其对再入气动稳定性的影响,始终保持在单配平点工况,以降低再入过程姿态、轨道控制技术难度。

After the end of orbital life of large-scale spacecraft, it is generally controlled to actively deorbit and complete its destructive re-entry in the Spacecraft Cemetery in the Southern Pacific Ocean, in order to avoid the risk of accidently depositing debris in populated areas. Aerodynamic effect is severe during the process of re-entry. The aerodynamic stability of spacecraft has direct impact on the reentry attitude and attitude hold, thus affecting the re-entry orbit. In this paper, the aerodynamic torque characteristics of the spacecraft under different working conditions are obtained by using fast aerodynamic methods, to analyze the influence of the centroid position and external components on the aerodynamic stability of the spacecraft. For spacecraft with given centroid position, as the external components disintegrate, the stability varies from one single neutral point to multiple neutral points. For different centroid positions, there is only a single neutral point when the centroid position is close to the end surface of the spacecraft, but multiple neutral points may appear when the centroid position is in the middle of the spacecraft. Therefore, for large-scale spacecraft, the centroid position and external components should be considered in the design stage in order to always maintain the aerodynamic stability at single neutral point, thus reduce the technical difficulty for re-entry control.