Effect of combined hole configuration on film cooling with and without mist injection

Abstract

Turbine blades operate under a harsh environmental condition, and the inlet temperature of gas turbines is increasing with requirement of high engine efficiency. Some cooling schemes are adopted to prevent these blades from the thermal erosion of the hot mainstream. Film cooling technology is used widely and effectively in gas turbines. The coolant air is suppressed to the wall by the main-stream after jetting out of the film hole. A new hole configuration is first pro-posed to improve the film cooling characteristics in this paper. Comparison be-tween a conventional cylindrical hole and a new combined hole is conducted by CFD, and effects of various blowing ratios and droplet sizes are also investigated. Results show that the combined hole configuration provides a wider coverage than that in the cylindrical hole configuration case at high blowing ratios (M = 1.0 and M = 1.5). In addition, the film cooling with mist injection also provides a significant enhancement on cooling performance especially for the combined hole case with a small droplet size (10?5 m).