压力侧冷却流对凹槽叶顶气膜冷却与传热性能的影响  

Effect of Pressure-Side Cooling Flow on Film Cooling and Heat Transfer Performance at Squealer Tip

作　　者：于金杏 叶明亮 何坤[1] 晏鑫[1] YU Jinxing;YE Mingliang;HE Kun;YAN Xin(School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China)

机构地区：[1]西安交通大学能源与动力工程学院,西安710049

出　　处：《西安交通大学学报》2022年第3期160-172,共13页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(52076165)。

摘　　要：为了降低凹槽叶顶整体热负荷并提高高传热区的气膜冷却效率,研究了压力侧冷却射流对透平级凹槽叶顶冷却传热性能的影响。通过数值计算获得了2种压力侧气膜孔形状(圆孔、扩张孔)和5种压力侧射流角(20°~40°)条件下,透平级凹槽叶顶的传热系数和气膜冷却效率分布。研究表明:前缘压力侧冷却流进入凹槽,增强了凹槽底部的冷却效果;中部和尾缘压力侧冷却流对凹槽肩壁和叶顶尾缘进行了冷却,增强了叶顶高热负荷区域的冷却效果。在所研究的射流角范围内,射流角越小,凹槽叶顶的冷却效果越好。当采用扩张孔、射流角由20°增大到40°时,肩壁的面积平均传热系数增大了6%,面积平均气膜冷却效率减小了14.3%;叶顶压力侧的面积平均传热系数增大了36%,面积平均气膜冷却效率减小了37.2%。在小射流角条件下,扩张孔的叶顶和压力侧冷却效果优于圆孔。射流角为20°时,与圆孔相比:扩张孔使凹槽肩壁面积平均传热系数减小了2%,面积平均气膜冷却效率增大了5.9%;扩张孔使叶顶压力侧的面积平均传热系数减小了22.6%,面积平均气膜冷却效率增大了43.3%。To reduce the overall thermal load at squealer tip and improve the film cooling effectiveness in high heat transfer areas,the influence of pressure-side coolant jet flow on heat transfer and film cooling performance of squealer tip in a turbine stage was investigated.The heat transfer coefficient and film cooling effectiveness at squealer tip with two kinds of cooling hole shapes(i.e.cylindrical and fan-shaped holes)and five different jet ejection angles(20°-40°)for pressure-side cooling holes were obtained through numerical simulations.The results show that the pressure-side cooling flow enters the cavity near the leading edge,improving the cooling effect on the cavity floor.The pressure-side coolant from the middle chord and near the trailing edge holes forms the cooling film on the tip surface and at the tip trailing edge,which enhances the cooling performance in the tip’s high thermal load area.In the present study,the cooling effect on squealer tip is increased with the decrease of ejection angle.For the fan-shaped holes at squealer tip,the area-averaged heat transfer coefficient is increased by 6%and the area-averaged film cooling effectiveness is decreased by 14.3%on the squealer rim,whereas the area-averaged heat transfer coefficient is increased by 36%and the area-averaged film cooling effectiveness is decreased by 37.2%in the tip pressure-side region,as the jet ejection angle increases from 20°to 40°.With small jet ejection angle,the film cooling effect on the squealer tip and pressure-side surface for the fan-shaped holes is better than that of cylindrical holes.If the jet ejection angle is fixed at 20°,the fan-shaped holes are able to decrease the heat transfer coefficient by 2%while increase the film cooling effectiveness by 5.9%on the tip surface,and decrease the heat transfer coefficient by 22.6%while increase the film cooling effectiveness by 43.3%on the pressure-side surface,as compared with the cylindrical holes.

关 键 词：燃气轮机 凹槽叶顶 传热 气膜冷却 扩张孔 射流角 

分 类 号：TK474.7[动力工程及工程热物理—动力机械及工程]