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 mainstrcam fluid should be corrected when it is applied into the practical design.