Diffuse reflection of thermal radiation transfer by Mie scattering can provide a thermal barrier without conversion leading to conduction heat transfer. Applying such a system to internal thermal insulating materials of a stand-off thermal protection systems (TPS) provides an efficient means of preventing thermal radiation transfer. Porous MgAlO ceramics have high thermal resistance because of their low radiation absorption over a wide range from visible to near-infrared wavelengths. For this study, after porous MgAlO ceramics was coated onto a fibrous insulator surface, we investigated its application to stand-off TPS, especially targeting reusable space transportation systems. Direct infrared heating tests were conducted in vacuum. Indirect infrared heating tests were done using graphite as a surface panel in an arc-heated wind tunnel with a high heat flux rate. The apparent thermal conductivity was obtained from the unsteady-state thermal history of the infrared heating experiment using an arc-heated wind tunnel to evaluate the radiation thermal barrier effects of the porous MgAlO ceramics. The low emissivity of porous MgAlO ceramics suppressed heat input and maintained a low surface temperature. Results suggest that thermal radiation transfer was suppressed and that the apparent thermal conductivity of the fibrous insulator was reduced.

中文翻译：

---

评估用于隔离热防护系统的低发射率多孔陶瓷涂层的辐射加热测试


米氏散射对热辐射传递的漫反射可以提供热障，而无需转换导致传导热传递。将这种系统应用于隔离热保护系统（TPS）的内部隔热材料提供了防止热辐射传递的有效方法。多孔 MgAlO 陶瓷具有高耐热性，因为它们在可见光到近红外波长的宽范围内具有低辐射吸收。在这项研究中，将多孔 MgAl2O3 陶瓷涂覆到纤维绝缘体表面后，我们研究了其在远程 TPS 中的应用，特别是针对可重复使用的太空运输系统。直接红外加热测试在真空中进行。使用石墨作为表面面板在具有高热通量率的电弧加热风洞中进行间接红外加热测试。表观热导率是通过电弧加热风洞红外加热实验的非稳态热历史获得的，以评估多孔 MgAlO 陶瓷的辐射热障效应。多孔 MgAlO 陶瓷的低发射率抑制了热输入并保持较低的表面温度。结果表明，热辐射传递受到抑制，纤维绝缘体的表观导热系数降低。