带前缘冲击复杂叶片内冷通道换热特性实验

Experimental investigation on heat transfer in complex internal cooling blade channel with leading-edge

采用瞬态热色液晶方法对不同雷诺数下静止状态涡轮工作叶片带前缘冲击复杂蛇形通道的换热特性进行了考察,得到了不同位置吸、压力面的表面传热系数分布.实验结果表明:相同雷诺数下,叶片通道内表面带肋区域两肋间的局部换热强于光滑区域,相邻两肋间的传热系数沿流动方向呈单峰分布.随着雷诺数增加,内表面传热系数提高,在弯头下游的光滑区域离心作用加强,带来该处局部换热分布不均匀,而弯头下游肋的出现可以削弱这种效果.此外,通道的收缩扩张导致主流速度的变化也给局部换热的数值和分布带来了影响.

Heat transfer characteristics of complex serpentine channels with leading-edge impingement in static turbine blade were investigated using the transient thermochromic liquid crystal technique under different Reynolds numbers.Distributions of local heat transfer coefficient at different positions were obtained on both pressure and suction sides.Experimental results show that：local heat transfer between two ribs is stronger than that in smooth region on inner surface of blade channels.A single heat transfer peak occurs between two adjacent ribs along the flow direction.With increase of Reynolds number,heat transfer is enhanced on all surfaces and centrifugal effect of fluid is strengthened in non-rib area downstream the bend,resulting in uneven distribution of local heat transfer there.However,ribs after the bend can reduce this effect significantly.Besides,mainstream speed changes caused by expansion and contraction of channel cross-section also influence the values and distributions of local heat transfer.