新型切向发散孔气膜冷却特性数值研究

Numerical Investigation on Film Cooling Performance of Novel Tangential Effusion Holes

关键词:  切向发散  气膜冷却  冷却效率  场协同  数值模拟

Key words:  Tangential effusion  Film cooling  Cooling effectiveness  Field synergy analysis  Numerical simulation

摘要:

为了探究火焰筒不同孔结构下的冷却特性，针对一种切向进气的发散孔火焰筒进行了不同工况下的数值研究，并基于场协同理论与常规倾角发散孔的火焰筒进行比较分析。结果表明，相比常规倾角的发散冷却，切向发散冷却结构具有更高的冷却效率，局部最高冷却效率在吹风比为10.4时可达0.98，火焰筒平均冷却效率高达0.93；同时，切向发散结构的气膜展向和流向均匀性也更好。随着吹风比的增大，切向发散冷却孔下游气膜的展向均匀性得到显著提高。常规倾角的发散结构在出流气膜附近的协同角较小，即主/次流掺混作用明显；切向结构在下游存在的较小协同角区域，但随着吹风比的增大而逐渐消失，主/次流之间掺混和换热作用的减弱是其极高冷却效率的关键。

Abstract:

In order to investigate cooling characteristics of the liner with different hole structures， numerical simulations were carried out for a tangential injection effusion cooling. Based on the Field Synergy Theory， the comparative results of tangential and conventional effusion under different operating conditions were analysed.The results show that the tangential effusion has higher cooling efficiency compared with the conventional effusion with inclination angles. The maximum local cooling efficiency can reach 0.98 at a blowing ratio of 10.4， and the average cooling efficiency of the liner is also as high as 0.93. In addition， the tangential effusion has better uniformity of cooling film along lateral and flow direction. With the increase of the blowing ratio， the lateral uniformity of the cooling film downstream of the tangential effusion is significantly improved. The small synergy angle was observed for the conventional inclination effusion， which implies that the intense interaction between main and second flow is occurred. The small synergy angle of tangential effusion in the near-wall region disappears when blowing ratio increases.The weakening of the mixing and interaction between main and secondary flows are the keys to its extremely high cooling effectiveness.