气凝胶夹芯金属热防护结构换热特性的实验研究

摘要

Experimental models of the metallic thermal protection system( TPS) with aerogel insulation were built up based on the need of the hypersonic vehicles.Different constructions of the aerogel insulation were designed with considering the effects of the cavity and arrangement of function layers.The thermal shock experiments were conducted under two temperature conditions of 773 K and 1 073 K.Important results of the experimental study include: the temperature-time variation pattern of cover sheet was deter-mined by the external temperature boundary conditions,and the change of insulation constructions had little influence on it.The aero-gel insulation had impressive performance in heat resistance,and its construction determined the heat transfer characteristics of the test model. In the temperature range of the present study,the radiation effect in the cavity hadn't played a dominate role on the heat transfer,when its heat transfer ability was similar to the aerogel insulation with same depth. The boundary condition for the internal sheet was similar to the adiabatic wall.The experiment data was useful in the design of the active cooling system for the internal cool-ing of TPS,and it also provided boundary conditions and validation basis for the numerical research.%根据飞行器热防护系统设计需求，建立了气凝胶夹芯金属热防护结构( TPS)的实验模型，考虑了多层绝热层、空腔、功能层排列方式的影响，在热端温度为773 K和1073 K两种热边界条件下，开展非稳态热冲击实验研究。实验结果表明，承载层的温度变化规律主要由温度边界条件决定，实验模型内部结构的变化对其没有明显影响；气凝胶绝热层的热防护效果明显，其变化对金属TPS结构的换热特性具有决定性的影响；在本文的实验温度范围内，空腔内的换热与相同厚度的低温绝热层的热传导能力相当；处于实验室大气环境的底层板的热边界条件接近于绝热壁面。实验结果可为金属TPS结构内的主动冷却结构设计提供参考，也可为相关数值模拟研究提供边界条件或验证数据。