冲击与气膜的组合形式对冷却效果的影响

通过数值模拟,研究了涡轮叶片弦中区所采用的新型双层腔冷却结构的冷却特性,系统分析了冲击与气膜的组合冷却流动换热的机理,讨论了冲击孔与气膜孔的组合形式对组合冷却效果的影响.计算参数范围是:吹风比M=0.6~2.0,冷气进口雷诺数Re=2000~5000.计算结果表明:①气膜孔与冲击孔的位置及其排列方式对双层腔结构的冷却效果的影响是非常明显的,且存在一个最佳的组合冷却形式;②在狭小的封闭空间内,冲击靶面的努塞尔数分布呈明显的双峰结构,冲击滞止点处于两个峰值之间的峰谷.

Effect of combined impingement cooling and film cooling on hybrid cooling effectiveness

The present study concentrates on the computational investigation of a new cooling configuration of a double-layer cavity in the middle section of modern turbine blade. A three-dimensional Navier-Stokes code with standard k-ε turbulence model as well as with wall functions was used to compute the flow and heat transfer characteristics for a combined impingement and film cooling configuration. The blowing ratios are from 0.6 to 2.0, and the Reynolds number based on the inlet velocity of the cooling air and hole diameter varied from 2000 to 5000. Additionally, the effect of the arrangement of both impingement hole and film hole on hybrid cooling effectiveness was discussed. Numerical results reveal that the maximum of hybrid cooling effectiveness is localized at a distance of 3.3d and 9d from the beginning of the cavity leading edge to film cooling hole and impingement hole, respectively. For the present computational domain, a double peak distribution of the Nusselt number on impingement target was demonstrated, and the stagnant point is localized at the valley between these two peaks.