改善横向波纹隔热屏综合冷却效率的发散冷却结构优化

Geometric Optimization of Effusion Cooling Configuration to Improve Overall Cooling Effectiveness for Transverse Wavy Shield

为改善横向波纹隔热屏综合冷却效果,采用三维数值模拟和基于支持向量机的代理优化模型,在给定的单位面积冷却空气流量下对发散冷却结构参数进行了优化研究。设计变量选取为气膜孔直径、气膜孔排布的展向间距和流向间距,以面积平均综合冷却效率作为目标函数,通过遗传算法搜索获得了设计变量区间内的优化设计点。在隔热屏单位表面积冷却空气流量Gf=2.647 kg/(m2∙s)的工况下,优化后的d、P和S分别为0.8、4和5 mm。研究结果表明,优化的隔热屏冷却结构应具有较小的气膜孔直径d和展向间距P,以及适中的流向间距S。相对于参考结构,优化后的发散冷却结构能够改善沿流向的气膜覆盖,缩减发散冷却起始段局部高温段,起到增强隔热屏发散冷却综合冷却效率的作用。

In order to improve the overall cooling effectiveness of a specific transverse wavy shield,we investigate the optimization of structural parameters of effusion cooling configuration. It is under a fixed coolant mass flow rate per unit area on the film-cooled surface,by using three-dimensional numerical simulation and support vector machine(SVM)-based surrogate model approximation. Three design variables are selected as film-hole diameter,streamwise hole-to-hole pitch and spanwise hole-to-hole pitch of an effusion cooling array. The genetic algorithm is used to search the optimal design point among the ranges of design variables,selecting the area-averaged overall cooling effectiveness as the objective function. Under the condition of Gf= 2.647 kg/(m2?s),the optimized d,P and S are 0.8,4,5 mm. The results show that the optimal cooling configuration of this transverse wavy shield has a smaller film-hole diameter,a smaller spanwise hole-to-hole pitch and a moderate streamwise hole-to-hole pitch. With respect to the reference cooling configuration,the optimized cooling configuration improves the film coverage along the streamwise direction and shortens the length of effusion-cooling initial developing zone with high temperature. As a consequence,the overall cooling effectiveness on the transverse wavy shield is enhanced.