EFFECTS OF TIP GAP FILM INJECTION FROM PLAIN AND SQUEALER BLADE TIPS

摘要

The present study investigates the effect of orthogonal tip gap film injection from a plain and squealer tip of a HPT first stage rotor blade. The pressure ratio (inlet total pressure to exit static pressure) for the cascade used was 1.2, and the experiments were run in a blow-down test rig with a four-blade stationary linear cascade. The Reynolds number based on cascade exit velocity and axial chord length was 8.61 x 10~5 and the inlet and exit Mach numbers were 0.16 and 0.55, respectively. Five holes are located along the camber line of the blade tip. A transient infrared technique was used to measure the local heat transfer coefficient and film effectiveness from a single transient test. All measurements were made for three blowing ratios of 1.0, 1.5, and 2.0. For all the cases, a small tip gap-to-blade span ratio of 0.5% was used. The squealer depth-to-blade span ratio of 4.16% was used for the squealer. Results show that the film injection has some effect for plain tips but has no effect or negligible effect for squealer tips.