热防护系统高温纤维隔热毡传热及有效热导率分析

针对重复使用运载器热防护系统纤维隔热毡内部导热和辐射的耦合换热问题进行了分析,应用有限差分法建立了纤维隔热毡的数值分析模型.通过数值求解传热方程,计算了稳态的有效热导率.计算结果表明辐射和气体传导是纤维隔热毡内的主要传热方式,辐射作用随压力和试样密度的增加而降低,在试样温度高的一侧辐射是主要的传热方式,而在温度低的一侧气体传导为主要的传热方式;试样的有效热导率随纤维的平均直径、压力和温差的增加而增加,随试样密度的增加而降低.本文的计算结果与文献中的实验结果吻合较好,可以为纤维隔热毡及热防护系统的优化设计提供理论参考.

Analysis of Heat Transfer and Effective Thermal Conductivity of High Temperature Fibrous Insulation for Thermal Protection System

The combined radiation/conduction heat transfer in hightemperature fibrous insulation of thermal protection system for reusable launch vehicles(RLV) is investigated in the present study.A numerical model analysis of thermal insulation is given by using one-dimensional finite differential technique.The governing heat transfer equations are solved numerically and effective thermal conductivity is calculated from the steady-state results.The results show that radiation and gas conduction are two main heat transfer mechanisms in fibrous insulation.Radiation decreases with increasing pressure and insulation density.Radiation is the main heat transfer mechanism on the hot side,while gas conduction is the main heat transfer mechanism on the cold side.The effective thermal conductivity of insulations increases with increasing the mean diameter of fiber,pressure and temperature difference and decreases with increasing insulation density.Calculation results are in good agreement with experimental data from literature.The results are helpful to the optimum design of fibrous insulation for reusable launch vehicles.