Peng Yubo, Xu Guoqiang, Luo Xiang, He Jian, Liu Dongdong
National Key Laboratory of Science and Technology on Aero Engines Aero-Thermodynamics, The Collaborative Innovation Center for Advanced Aero-Engine of China, Beihang University, Beijing 100191, China.
Micromachines (Basel). 2022 Mar 16;13(3):450. doi: 10.3390/mi13030450.
We experimentally investigate the transpiration cooling characteristics of a porous material, sintered wire mesh. Three samples with different porosities in a plain weave structure are tested with various blowing ratios in an open-loop wind tunnel with a heated mainstream flow. The temperature on the surface of the porous material is measured by an infrared camera to obtain the cooling efficiency. The measurements reveal nonuniform distributions of the surface temperature and the cooling efficiency in both the flow direction and the transverse direction. The averaged cooling efficiency on the surface first decreases and then increases with the blowing ratio, but increases and then decreases with the porosity of the material. The internal cooling by forced convection and its combination with the external film cooling from the transpiration cooling are considered to be attributed to those two cooling characteristics, respectively. Finally, we propose a modified blowing ratio to collapse the minima of the blowing ratio for all tested samples, providing an universal transition for the decreasing and increasing branches for all tested samples in the relation between averaged cooling efficiency and blowing ratio.
我们通过实验研究了一种多孔材料——烧结金属丝网的发汗冷却特性。在具有加热主流的开环风洞中，对三种具有不同孔隙率的平纹编织结构样品，以不同的吹风比进行了测试。用红外热像仪测量多孔材料表面的温度，以获得冷却效率。测量结果表明，表面温度和冷却效率在流动方向和横向方向上均呈非均匀分布。表面平均冷却效率随吹风比先降低后升高，但随材料孔隙率升高后降低。强迫对流引起的内部冷却及其与发汗冷却的外部气膜冷却的组合，分别被认为是导致这两种冷却特性的原因。最后，我们提出了一种修正的吹风比，以使所有测试样品的吹风比最小值重合，为所有测试样品在平均冷却效率与吹风比关系中的下降和上升分支提供一个通用的转变。
