反演航天器在轨瞬态外热流的导热反问题

获得航天器在轨飞行过程中的外热流数据对于研究热控涂层在轨退化规律、各种空间因素对热控产品的影响以及航天器姿轨控发动机羽流热效应都有非常重要的意义,然而直接测量热流存在很多困难,因此可以通过求解导热反问题得到满足一定精度的结果.首先,通过研究利用航天器设备在轨遥测温度值反演出航天器在轨瞬态外热流的导热反问题方法,建立了反演航天器在轨瞬态外热流的数学模型,采用共轭梯度法求解导热反问题并从物理概念角度改进了共轭梯度法的迭代过程以增加其抗不适定性;然后构造了两组能够代表目前大多数地球轨道航天器以及深空探测航天器在轨吸收外热流变化的数值试验对共轭梯度法的反演效果进行了检验.除阶跃变化位置以外反演值与真实值的最大相对偏差为2.9%,反演效果非常好;对于阶跃变化位置的吸收外热流在对反演结果进行分析处理后也能够得到较好的反演结果.

Inverse heat conduction problem for transient external heat flux inversion of spacecraft on orbit

Spacecraft external heat flux is very important for researching deterioration law of thermal control coating on orbit, influence of various spatial factors on thermal control products, as well as plume thermal effect of spacecraft attitude and orbit control engine. However, there are many difficulties in direct heat flux measurement. Thus, the inverse heat conduction problem can be used to get results which can satisfy certain precision. Firstly, in order to deduce transient external heat flux of spacecraft on orbit from telemetry temperature of spacecraft equipment on orbit, inverse heat conduction problem mathematical model was set up and solved by the conjugate gradient method. Iterative process of conjugate gradient method was improved according to physics concept in order to increase its anti instabilit. Then, two numerical tests were used for the purpose of checking mathematical model effect. The numerical tests could represent external heat flux change of most both earth-orbiting spacecraft and deep space exploration spacecraft. The maximum relative deviation between inversion value and true value is 2.9% except step change data. Inversion results of the mathematical model is very good. Furthermore, satisfied results can be obtained by processing data analysis for absorbed external heat flux at step change location.