Effects of film hole spanwise angle and diameter on flow and heat transfer of impingement/effusion cooling with crossflow diverters

Abstract

This paper studies the blade cooling under the co-effect of external film extraction and internal impingement cooling with crossflow diverters. The influence of spanwise angle (α) and diameter (Df) of film hole on flow and cooling performance are analyzed when the impingement jet Reynolds number ranges (Rei) from 15,000 to 45,000. From the results, if a row of film holes is set on the target surface of an impingement cooling with crossflow diverters, the overall cooling effectiveness will be greatly improved, especially the pressure side. When the α ranges from 35° to 115°, no matter pressure side or suction side, the film jet injection towards blade hub is more beneficial to cooling, and the smaller the α, the more beneficial. When the Df ranges from 0.25 mm to 1.00 mm, at suction side, as Df increases, overall cooling effectiveness gradually increases; at pressure side, when the Df ranges from 0.25 mm to 0.75 mm, overall cooling effectiveness increases, but if the Df continues to increase, it will decrease, which means the Df of 0.75 mm can obtain the most excellent cooling performance. This study provides a theoretical basis for the comprehensive application of film extraction, impingement cooling, and crossflow diverters in blade cooling design.

Keywords

• Impingement/effusion cooling
• Spanwise angle
• Diameter
• Overall cooling effectiveness
• Blowing ratio