Flow visualization and film cooling effectiveness measurements around shaped holes with compound angle orientations

Experimental results are presented which describe film cooling performance around shaped holes with compound angle orientations. The shaped hole has a 15 degrees forward expansion with an inclination angle of 35 degrees, but the orientation angles vary from 0 degrees to 30 degrees and 60 degrees. The blowing ratios considered are 0.5, 1.0 and 2.0. Flow visualizations are performed using an aerosol seeding method for single enlarged shaped hole to investigate the interaction between the mainstream and the injectant at the hole exit plane. The adiabatic film cooling effectiveness distributions are measured for a single row of seven shaped holes using the thermochromic liquid crystal technique. Flow visualization reveals the occurrence of hot crossflow ingestion into the film hole at the hole exit plane at a large orientation angle such as 60 degrees. Shaped holes with simple angle injection do not provide substantial improvement in the film cooling performance compared to round holes. However, shaped holes with compound angle injection exhibit improved film cooling effectiveness up to 55% in comparison with round hole data at high blowing ratios. (C) 2001 Published by Elsevier Science Ltd.