带60°肋U型通道中气膜孔对通道换热特性的影响

Effect of Bleeding Holes on Heat Transfer Characteristics Inside U-Shaped Channel with 60° Skewed Ribs

以航空发动机涡轮叶片中段内部冷却通道为研究对象,将其简化为带肋变截面U型通道。对通道内有气膜出流时的换热特性进行了实验研究。实验模型中,矩形肋对称布置在上下2个表面,气膜孔仅布置在第2通道内。文中定义了气膜开孔率的概念,采用单元分析法研究了气膜开孔率和出流比对通道内单元努塞数分布和第2通道压力分布的影响。实验结果表明,气膜出流比一定时,随着开孔率的增加,换热增强;在两肋之间的3个气膜孔中,肋后孔对通道换热影响最大;气膜出流比与通道努塞数的关系为二次曲线。

The internal coolant channel in an actual turbine blade was simplified into a variable cross-section channel with ribs and bleeding holes. The effect of bleeding holes on the heat transfer characteristics was experimentally studied. The bleeding holes were located in the secondary pass only. Hole opening ratio was defined ,and the local analysis method was applied. The effects of the hole opening ratio and the exit mass flow rate on heat transfer and the effect on the pressure distributions at the location of the bleeding holes were experimentally studied. Analysis of the results lead to the following conclusions：with the increase of the hole opening ratio, the heat transfer is enhanced while the exit mass flow rate keeps constant ;the local Nusselt Numbers decrease with the increase of the exit mass flow rate while the hole opening ratio keeps unchanged.