Effect of mass flow ratio on heat transfer coefficient of a film cooled vane

The heat transfer coefficients of a turbine nozzle guide vane with and without a film cooling hole were measured by the transient liquid crystal technique at the Reynolds number of the inlet flow of 108 000 and the mass flow ratio of 0, 3.46%, 4.61%, 5.77%, 6.93%, 8.08% and 9.23%, respectively. The effects of film cooling flow and the mass flow ratio on the heat transfer coefficient were investigated. The pressure distribution at the middle section of the vane without the film cooling hole, and the detailed distribution of the heat transfer coefficient and the mean heat transfer coefficient curves at different mass flow ratios were obtained. The results show that there was a flow transition on the vane suction side. The film cooling flow advanced the beginning location of the transition on the suction side and reduced the transition length. In addition, the heat transfer coefficient in the area with the film cooling hole (such as leading edge, the front of pressure side and suction side) increased significantly, but the heat transfer coefficient in the area beyond the transient location changed slightly. In this experiment, the heat transfer coefficient increased almost linearly with an increase in the mass flow ratio.