Conjugate heat transfer and flow analysis on double-wall cooling with impingement induced swirling and film cooling

A novel double-wall cooling configuration with impingement induced swirling film cooling is investigated in present paper. The effects of impingement inclined angle, blowing ratio, film hole length-diameter ratio and Biot number on conjugate heat transfer characteristics are studied by numerical simulations. The formation, development and evolution of the vortex and the reconstruction process of vortex structures are analyzed. The results indicate that impingement inclined angle can increase the swirling intensity and destroy the kidney-shaped vortex of external film cooling. The spanwise average overall cooling effectiveness is improved by about 20% when the impingement inclined angle is increased from 15° to 30°. Increasing blowing ratio makes the kidney-shaped vortex gradually evolve into multiple vortex structures in the mainstream, thereby increasing the adhesion of coolant and improving the overall cooling effectiveness. The overall cooling effectiveness fluctuates with the increase of length-diameter ratio, due to the large length-diameter ratio destroying the external film cooling. When the Biot number is small, the internal impingement induced swirling cooling determines the cooling performance, and when the Biot number is large, the cooling performance is mainly affected by the external film cooling.