Abstract A local thermal non-equilibrium analysis has been proposed for the gaseous transpiration cooling in which a coolant gas is driven from a coolant reservoir through a wall of porous structure to remove heat from a hot gas passing over the wall. For the first time, the effects of both radiation and gas expansion on the performance of the transpiration cooling were fully taken into consideration, on the basis of equal pumping power needed to supply the coolant, by introducing the Rosseland and low Mach approximations. The present analysis valid for all cases, in which both radiation and gas expansion are present, was validated against the existing analyses for the cases of incompressible transpiration gas flows in the absence of radiation. The radiative heat transfer tends to reduce the overall cooling effectiveness, but, at the same time increase the total removable of heat from the hot gas. The low Mach approximation is found quite effective to account for the gas expansion effects on the pressure drop across the wall. Furthermore, the analysis reveals that the overall Nusselt number exhibits its peak at a certain value of the pumping power, which turns out to be useful information in operating a transpiration cooling system effectively around its optimal flow rate.

中文翻译：

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通过多孔壁的气态蒸腾冷却中对流和辐射传热的局部热非平衡分析

摘要 已经提出了一种用于气态蒸发冷却的局部热非平衡分析，其中冷却剂气体从冷却剂储存器中通过多孔结构的壁被驱动，以从穿过壁的热气体中去除热量。通过引入 Rosseland 和低马赫近似，在提供冷却剂所需的泵功率相等的基础上，首次充分考虑了辐射和气体膨胀对蒸腾冷却性能的影响。本分析适用于所有情况，其中辐射和气体膨胀都存在，并根据现有分析在没有辐射的情况下对不可压缩蒸腾气流的情况进行了验证。辐射传热往往会降低整体冷却效率，但是，同时增加从热气中去除热量的总量。发现低马赫近似非常有效地解释了气体膨胀对跨壁压降的影响。此外，分析表明，总体努塞尔数在泵送功率的某个值处显示出峰值，这对于在其最佳流速附近有效地运行蒸腾冷却系统而言是有用的信息。