Effects of plasma actuation and hole configuration on film cooling performance

In this paper, plasma actuators are arranged asymmetrically downstream the wall to improve film cooling performance. Effects of blowing ratio, hole configuration and applied voltage on flow characteristics and film cooling effectiveness were investigated numerically on a flat plate. Results show that highest film cooling effectiveness distribution is obtained both in the spanwise and streamwise directions under blowing ratio of 0.5. Average wall film cooling effectiveness of cylindrical hole increases by 251.9% under blowing ratio of 0.5 compared to that under blowing ratio of 1.5. The scale of the counter rotating vortex pairs (CRVP) from fan shaped hole and sister hole are significantly reduced compared to that from cylindrical hole. The console hole has an anti-counter rotating vortex pair (Anti-CRVP), which weakens the entrainment of the CRVP to the coolant air near the wall. Compared with the cylindrical hole, average wall film cooling effectivenesses for fan shaped hole, sister hole and console hole increase by 73.1%, 97.5% and 119.9%. The adherent performance of the coolant air is enhanced after applying plasma actuator. The aerodynamic actuation of the plasma results in the rebound of the fluid close to the wall at 24 kV applied voltage. Average wall film cooling effectiveness of the console hole at 12 kV applied voltage is 10.6% higher than that without plasma.