Effect of compound angle injection on flat surface film cooling with large streamwise injection angle

Abstract

Film cooling measurements are presented over a flat surface through a single row of discrete holes angled 55° along the streamwise direction. The holes are angled 0° and 60° in the lateral direction to study the effect of compound angle injection. Detailed heat transfer coefficient enhancement and film effectiveness distributions are presented for the entire region from downstream of the holes to distances far downstream at about X/d=20. Tests were conducted in a low speed wind tunnel. The mainstream flow Reynolds number based on hole diameter is around 9500 and the free-stream turbulence intensity is set at 11%. Results are presented for three blowing ratios of 0.5, 1.0, and 1.5 and a coolant-to-mainstream density ratio of 1.0. A transient liquid crystal technique will be used to measure both the local heat transfer coefficient and film effectiveness results simultaneously. The technique uses two similar tests to resolve the heat transfer coefficient and film effectiveness. The detailed heat transfer coefficient and film effectiveness contours provide a clear understanding of the jet–mainstream interactions for different hole orientations with large streamwise angle injection. Results show that adding a compound angle to a hole with large streamwise angle produces significant variations in the detailed film effectiveness distributions and enhances local heat transfer coefficients.