直径比对冲击气膜组合冷却流动与换热的影响

 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，系统分析了冲击气膜组合冷却的流动与换热特性，讨论了冷气进口雷诺数Re、吹风比M以及气膜孔与冲击孔的直径比D/d对组合冷却效果的影响。计算参数范围是：冷气进口雷诺数Re＝2 000～5 000，吹风比M＝0.6～2.0。计算结果表明, 冷气进口Re,M以及D/d对双层腔结构冷却效果的影响非常明显，在计算范围内:（1）Re和M越高，冷却效果越好;（2）当冲击孔直径一定时，增加气膜孔的直径，冷却效果会随之增加;（3）当冲击孔直径一定时，增加气膜孔的直径，流阻系数会随之减小。

Effects of Diameter Ratio on the Characteristics of Flow and Heat Transfer in Hybrid Cooling Configuration

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 wall functions is used to compute the flow and heat transfer characteristics for a combined impingement and film cooling configuration. The blowing ratio ranges of 0.6~2.0, and the Reynolds number based on the inlet velocity of the cooling air varies from 2 000 to 5 000. Details of the effect of the ratio of film hole diameter to jet hole diameter, D/d on hybrid cooling effectiveness are discussed. Numerical results show that a larger hybrid cooling effectiveness and a lower flow resistance are reached with the increase of the diameter of film cooling hole, while the diameter of impingement hole is fixed.