具有新型双层壁结构的透平叶片流热耦合研究

Research on Conjugate Heat Transfer of Turbine Blades with a Novel Double-wall Structure

多通道壁面射流冷却结构是一种新型的燃气透平动叶内部冷却结构,具有消耗冷气少、压力损失小等优点。本文构建了简化的壁面射流冷却叶片与GE-E3冷却结构叶片模型,采用流热耦合方法对比研究了其流动与换热特性。结果表明,壁面射流冷却通道内的狭小空间抑制了横流的产生,冷气在冷却通道中形成了流向涡;前缘冷气流道中的大量冷气流经吸力侧冷却区,并从出口压力更小、面积更大的尾缘排出,使得前缘气膜孔出流的冷气流量和动量较小,冷气在叶片外表面的气膜覆盖特性更好;离心力的影响导致前缘冷气流道中叶根处的压力较低,叶根附近的气膜孔出现燃气主流入侵现象。相比于GE-E3叶片,壁面射流冷却叶片的前缘温度和温度梯度都较小,因此多通道壁面射流冷却在前缘具有更优异的冷却特性。

Multi-channel wall jet cooling structure is a novel internal cooling structure for gas turbine blades,which has advantages of less coolant consumption and low pressure loss.The simplified blade with wall jet cooling and GE-E3 blade are built,and their flow and heat transfer characteristics are studied comparatively by using the conjugate heat transfer method.The results show that the narrow space in the wall jet cooling channel suppresses the occurrence of crossflow,and cooling air forms streamwise vortices in the cooling channel;lots of coolant from air chamber at the leading edge flows through the cooling area on the suction side,and then is discharged from the trailing edge with low outlet pressure and large outflow area.The cooling air discharged from the film holes at the leading edge has lower flow rate and momentum,which contributes to better film coverage characteristics for cooling air on the outer surfaces of the blade;centrifugal force decreases the pressure at the root of the blade in the cooling chamber at the leading edge,which results in mainstream intrusion.Compared with the GE-E3 blade,the temperature and its gradient at the leading edge are lower for the blade with wall jet cooling,so multi-channel wall jet cooling has better cooling characteristics for the leading edge.