Experimental and Numerical Evaluation of the Film Cooling Characteristics of the Multi-cavity Tip with Inclined Film Holes

Due to the complex flow field and the considerable heat load on the turbine blade tip, film cooling is essential to protect the tip from being overheated. In this paper, an experimental work was conducted to compare the film cooling distributions of four tip structures (cavity numbers are one, two, three, and four) with two film hole configurations (perpendicular and 45 degrees inclined to the cavity floor) under three coolant blowing ratios. By using pressure sensitive paint technique, the distributions of film cooling effectiveness were measured. Moreover, a computation with careful validation was executed to obtain the cooling traces in the tip region and compare the aerodynamic performance of these multi-cavity tips. The results showed that the value and uniformity of film cooling effectiveness were improved by the inclined configuration. The tip film cooling was enhanced when using the multi-cavity tips. The aerodynamic loss of the tested tips was compared as well.