叶片内部气膜孔附近壁面局部换热特性

Heat transfer characteristics near a row of film cooling holes in interior of turbine blade

关键词:  涡轮叶片  薄膜冷却  溢流效应+  传热

Key words:  Turbine blade  Film cooling  Extraction effect~+  Heat transfer

摘要:

对叶片弦中区内部“冲击-气膜出流”冷却方式中气膜孔附近壁面的换热特性进行了实验研究。取气膜孔前后三倍气膜孔径范围为研究对象,重点研究了冲击间距及冲击孔与气膜孔沿流向相对位置对其换热的影响规律。研究发现:对气膜孔前后局部范围,存在最佳的冲击间距与气膜孔径比;同样,对气膜孔前局部范围,也存在最佳的冲击、气膜孔沿流向相对距离与气膜孔径比;随着冲击孔与气膜孔相对距离的增大,冲击对气膜孔局部换热影响变小,气膜“溢流效应”突出,越靠近孔的地方换热越强。

Abstract:

Investigation of local heat transfer characteristics near film cooling holes about inner side of turbine blade midchord area with impingement was carried out experimentally.The research is focused on the three diameter area upstream and downstream a row of film cooling holes.The impinging distance and the distance between impinging holes and film holes influence the heat transfer near film holes,and the effect was mainly investigated.In the range of experimental parameters,the experimental results indicate that there is optimal ratio of the impinging distance to film hole diameter.Similarly,there is optimal ratio of the distance between impinging jets and film holes to film hole diameter upstream film holes.As impinging holes keep away from film cooling holes in the flow direction, the effect of impingement on local heat transfer near film cooling holes is weakened,and film cooling extraction effect stands out,and the place closer to the hole will have stronger heat transfer whether before the film holes or behind the holes.