Thermal Protection System Structures for the Space Transportation System

对钛多壁热防护系统(TPS)进行了暂态热分析。多壁TPS概念由交替的扁平和凹陷薄板组成，它们在凹陷薄板的顶部焊接在一起，并形成方形瓷砖，这些瓷砖机械地附着在空间运输系统的主要结构上。本研究的目的是介绍一种钛多壁TPS的隔热性能。考虑了三种换热模式，即通过瓷砖内部气体的传导、通过金属的传导和相邻薄板之间的辐射。通过考虑三种换热模式的稳态分析，解析地得到了有效导热系数。文中给出了各种换热方式对各种参数的贡献。在相对较低的温度下，气体传导是主要的换热方式，而在较高的温度下，辐射成为主要的换热方式。利用一维有限元模型，考虑有效导热系数和其他材料性质对温度的依赖关系，计算了厚度方向上的温度分布及其时间历程。结果表明，在TPS设计条件下，铝合金主结构的温度足够低。

Transient thermal analyses of a titanium multiwall thermal protection system (TPS) are presented. The multiwall TPS concept consists of alternate flat and dimpled sheets which are welded together at the crests of the dimpled sheet, and it is formed into square tiles which are mechanically attached to the primary structure of the space transportation system. The purpose of this research is to present a heat isolation property of a titanium multiwall TPS. Three modes of heat transfer are considered, that is, conduction through the gas inside the tiles, conduction through the metal and radiation between the adjoined sheets. An effective thermal conductivity is obtained analytically from a steady state analysis considering the three modes of heat transfer. The contributions of each mode of heat transfer to various parameters are shown. Gas conduction is major mode of heat transfer at relatively low temperatures, and radiation becomes dominant mode at higher temperatures. Temperatue distributions through the thickness and their time histories are also calculated considering the temperature dependence of the effective thermal conductivity and other material properties using the one-dimensional finite element model. The results indicate that the temperature of the aluminum primary structure for the TPS design condition is sufficiently low.