窄通道内冲击冷却局部换热特性的瞬态液晶测量

 为了深入了解涡轮叶片中冲击窄通道内的换热特性，采用热色液晶瞬态测量技术测量了冲击窄通道内全表面换热系数，获得了不同冲击雷诺数Re、相对冲击孔间距S/d以及有无气膜孔出流时通道内各表面的换热系数分布规律。结果表明：冲击通道内各个面的换热系数均随雷诺数的增加而增加，其中冲击靶面的平均换热系数最大，在雷诺数较大时，冲击面的平均换热系数要比冲击侧面的大；气膜孔出流和相对冲击孔间距增大均会使冲击侧面和冲击面的平均换热系数明显减小，而对冲击靶面平均换热系数的影响却较小；各个面上受气流直接冲击的区域换热系数最大，同时冲击孔和气膜孔附近区域的换热系数也很大。

Local Heat Transfer Measurements in Narrow Impingement Channel by Transient Liquid Crystal Technique

A transient liquid crystal technique is used to measure the local heat transfer coefficients on the inner surfaces of an impingement channel that models the cooling passages in gas turbine blades. The effects on the heat transfer of jet Reynolds number Re and the ratio of the jet-to-jet spacing to the diameter of the jet hole S/d are investigated. The effect of the film holes is also studied. Results show that the heat transfer coeffi-cients on all surfaces increase with an increase in jet Reynolds number, and that the average heat transfer coef-ficient on an impingement target surface is the highest. When the jet Reynolds number is sufficiently high, the average heat transfer coefficient on an impingement surface is higher than that on the channel side. The bleed-ing of film holes and increase in S/d both tend to significantly decrease the average heat transfer coefficients on the channel side and impingement surface, but its effect on the target surface is comparatively small. Heat transfer coefficient in the region which is directly subjected to the impingement flow is the highest for every in-her surface, while in regions around jet holes and film holes it also remains fairly high.