SiO2气凝胶隔热性能的影响因素研究

目的 在不同热流条件下，通过调整SiO2气凝胶的孔隙率、涂层厚度等，以满足合适的隔热要求。方法 针对中短程飞行器飞行时外壁面承受短时高热流的特点，在分析孔隙率对SiO2气凝胶热导率影响规律的基础上，通过数值仿真研究不同气凝胶孔隙率、气凝胶厚度及热流作用下的温度响应。结果 得到了不同条件下满足隔热要求的气凝胶最小厚度，以及气凝胶表面的最高温度。高温情况下，气凝胶孔隙率为96%时，有效热导率最低，孔隙率超过96%时，隔热性能变差。结论 当飞行器内壁面温度满足要求时，增大气凝胶的孔隙率，则需要减小气凝胶的厚度，相应的气凝胶表面温度会升高，但升幅很小。当飞行器外壁面承受长时间大热流时，仅调整气凝胶的厚度和孔隙率不能达到结构的隔热要求。

Influence Factor of Thermal Insulation Performance of SiO2 Aerogel

In order to getthe structure design of SiO2 aerogel that meet the insulation requirements under heat flux. According to the characteristics of short-range flight vehicle that bearing short time high heat flux, the effect of porosity on thermal conductivity of SiO2 aerogel is analyzed in this study. Using the finite element method, the minimum thickness of aerogel that meet the insulation requirements under heat flux, and the effect of magnitude and time of heat flux on the surface temperature of aerogel have been investigated. The results show that, the high temperature effective thermal conductivity of aerogel is the lowest when the porosity is 96%, and then becomes worse when the porosity is over 96%. Reducing the thickness of aerogel requires higher aerogel porosity due to the inner wall temperature of the structure. When the structure is subjected to long time high heat flux, only adjusting the thickness and porosity of the aerogel cannot meet the thermal insulation requirements. The results provide a basis for the structure design of SiO2 aerogel that meet the insulation requirements under heat flux.