涡轮叶栅前缘上游端壁气膜冷却的传热实验研究

对前缘上游有单排和双排孔冷却的涡轮导向叶栅端壁进行了详细的传热实验,在吹风比1,2,3下获得了当地气膜冷却效率和换热系数,结合流场测量结果分析了端壁冷却和换热规律。结果表明端壁气膜冷却在很大程度上受二次流的影响,冷却效果主要由吹风比决定,低吹风比喷射时,压力面附近的一个三角形区域没有冷气的覆盖,中、高吹风比喷射可以大幅度提高平均冷却效率并使冷气很均匀的覆盖在端壁上,双排孔喷射比单排孔喷射平均效率提高1倍左右。结果还表明尽管冷气喷射使端壁换热系数随吹风比的增大而显著增大,气膜冷却还是能有效的降低端壁的热负荷,其中以中吹风比双排孔喷射的效果最为显著。 

Endwall Heat Transfer and Film Cooling Measurements in a Turbine Cascade with Injection Upstream of Leading Edge

WT5BZ]Detailed heat transfer measurements were conducted on the endwall surface of a large scale low speed turbine cascade with single and double row injection on the endwall upstream of leading edge.Local film cooling effectiveness and heat transfer coefficient with coolant injection were determined at blowing ratio 1,2 and 3.In conjuction with the previous measurement flow field,the behaviours of endwall film cooling and heat transfer were studied.The results show that endwall film cooling effectiveness is influenced to a great extent by the secondary flow and the coverage of the coolant on the endwall is mainly determined by blowing ratio.An uncovered triangle shaped area with low effectiveness close to pressure side could be observed at low blowing ratio injection.The averaged effectiveness increases significantly when injecting at medium and high blowing ratio,and quite uniform coverage of coolant on the endwall could be achieved.The averaged effectiveness could be doubled in case of double row injection.It was also observed that coolant injection made the overall averaged heat transfer rate increase remarkably with blowing ratio and then made the thermal loads on the endwall decrease effectively.Large increments of heat transfer rate could be happened at cascade entrance and exit and in the area near suction surface.