Numerical Simulation of Steady Plasma Actuation on Improving Film Cooling Efficiency

To explore the mechanism of plasma aerodynamic actuation on improving the cooling efficiency of flat plate film, by a large eddy simulation, we investigated the effects of the position and number of plasma actuator on the film cooling performance, and adopted the phenomenological plasma model to represent the plasma-induced body force generated by actuator on the fluid. Results show that as the distance between the plasma actuator and the cooling hole exit decreases, the downward momentum effect of plasma on the cooling jet grows larger, and the jet trajectory stays closer to the wall. When the plasma actuator is installed at x/d=0, the maximum jet exit streamwise and vertical velocities will increase by 10% and 3%, respectively, but the vertical velocity near the leading edge decreases by 2%, then the mixing process of between the jet and the crossflow at the upwind side of the jet is suppressed, and the kidney shaped vortex loses its strength, thus the centerline film cooling efficiency will increase by 40%. Moreover, due to the downward momentum and momentum injection effects of the second plasma actuator, the cooling jet stays closer to the wall and stretches farther downstream with two plasma actuators, and the hairpin vortex breaks into smaller near-wall streaks, so the centerline and lateral-averaged film cooling efficiency will increase by 17% and 40%, respectively, compared with the single-plasma actuator case. In addition, under the same actuation strength, optimization arrangement of actuator number can promote the performances of plasma actuation in improving film cooling efficiency.