密度比对涡轮叶片表面气膜冷却换热系数的影响

 采用放大的叶片模型，利用大尺寸低速线性叶栅风洞进行试验，测量了涡轮工作叶片表面不同位置处气膜孔下游叶片表面的换热系数，研究了不同吹风比、密度比和雷诺数的影响。风洞试验段由3个叶片组成，其中中间的叶片为试验叶片。试验叶片表面上开有6排气膜孔，其中吸力面1排，前缘区3排，压力面2排。试验结果表明：密度比对叶片表面气膜孔下游换热系数有影响，以往采用空气作为主流及二次流，在低温差下进行试验，所获得的叶片表面气膜孔下游的换热系数在用于涡轮叶片气膜冷却的实际设计时，必须进行修正。

Influences of Density Ratio on Film Cooling Heat Transfer of Turbine Blade Surface

Heat transfer coefficients downstream of film row at different locations on turbine blade surface were studied experimentally.A three-blade liner cascade in a large-scale low-speed opening wind tunnel was used in the experiment.There were 6 rows of film cooling holes at the middle blade and one row on the suction surface,three rows on the leading edge and wto rows on the pressure surface.Heat transfer coefficients on the blade surface were measured at different blowing ratios and density ratios and the same Reynolds number.The results show that the heat transfer coefficients on turbine blade surface are affected significantly by the density ratio of secondary to mainstream fluid,that the data of turbine blade surface heat transfer coefficients are measured at low difference in temperature with air as secondary and mainstream fluid should be corrected when it is applied into the practical design.