金属多层隔热结构反射屏热阻对传热性能影响数值分析

Numerical Analysis of Multi-Layer Insulation Foils′ Thermal Resistance′s Influence on Thermal Conductivity

针对金属多层隔热结构中反射屏的附加辐射热阻、反射屏与纤维层的接触热阻对热传导性能的影响展开数值分析,首先基于有限容积法和二热流法建立了离散化的系统热传导方程组,然后分析计算了反射屏在瞬态和稳态热传导过程中对辐射热流的抑制以及等效的附加辐射热阻;最后结合多点接触热阻分析理论,推导了反射屏与纤维层接触热阻的计算公式,并分析了纤维层填充压力和松紧度对接触热阻和热传导性能的影响,从而为改进金属多层隔热结构的性能和可靠性提供了参考。

We carry out a numerical analysis about the restraining effect of the foils on radiation thermal flow in the multi-layer insulation （MLI） and about the influence of the contact thermal resistance between foils and the fiber insulation on the MLI＇s inner local temperature distribution. Section 2 of the full paper builds the discrete thermal analysis numerical model using the finite volume method and the two-flux method. Section 3 analyzes the foils＇ control effect on MLI＇s radiation thermal flow under either steady- state or transient-state conditions and also calculates the effective radiation resistance; it gives calculated results in Figs. 3 through 5 and Table 1. Section 4 derives eq. （9） as the theoretical equation of the contact thermal resistance between the foils and the fiber insulation for analyzing the influence of the fiber insulation＇s load pressure and its tightness on the contact thermal resistance and also on the MLI＇s thermal conductivity; it gives calculated results in Tables 2 through 5. On the basis of the analysis of the calculated results given in Figs. 3 through 5 and Tables 1 through 5, section 5 gives preliminarily five conclusions that, in our opinion, can be useful in designing and manufacturing the MLI so as to make it more effective and more reliable.