小卫星瞬态外热流下动态传热特性分析

为揭示小卫星瞬态外热流下的动态传热特性规律,以小卫星双层集总参数模型为研究对象,推导得到动态热平衡方程。类比阻尼振荡系统,采用时频变换和传递函数分析的新思路,对温度与热流波动量间的幅值特性和相位特性变化规律进行理论研究,并利用数值方法进行验证。结果表明:推导获得了小卫星传热系统自然频率和阻尼比的热参数准则式,并证明了小卫星传热系统在热激励下振荡特性为过阻尼。阻尼比和频率比的增大及热流静位移的减小均可降低温度的波动幅度,不同频率比范围下阻尼比对热流的波动量与温度波动量间的相位差的影响呈相反规律,数值结果与解析分析结果一致。可为低热惯性小卫星的热控优化设计提供理论参考。

Analysis on Dynamic Heat Transfer Characteristics for Microsatellites Influenced by Transient External Heat Flux

The transient heat transfer balance equation is deduced based on the double-layer aggregate model for the microsatellite,in order to study rules of dynamic heat transfer characteristics. Analogous to damped oscillation systems, the rules about amplitude and phase characteristics between temperature fluctuation and heat flux fluctuation are obtained by using a new method of time frequency transform and transfer function analysis. The working method is proved by numerical calculation. The expressions of thermal parameters on the natural frequency and the damping ratio are deduced for the heat transfer system of the microsatellite, which is proved to be an over-damping system. The variation amplitude of temperature fluctuation decreases, when damping and frequency ratios increase, or static displacement decreases. The changing rules of phase difference is opposite with varying damping ratios in different ranges of frequency ratios. Moreover, the results from analysis and numerical simulation are agreed. It can provide the theoretical reference for the thermal control optimization design of small satellites with low thermal inertia.