Large eddy simulation of film cooling flow characteristics under different plasma actuation strengths

In order to improve the film cooling efficiency of the gas turbine blade, effects of the strengths of the plasma actuation on the flat plate film cooling flow characteristics were conducted using large eddy simulation (LES). Results show that compared with the non-plasma actuation case, as the plasma actuation strength grows larger, the maximum jet exit streamwise and vertical velocities increase 16% and 7%, respectively, and shift to the trailing edge, but the vertical velocity near the leading edge decreases 4%, thus the mixing process between the jet and the crossflow at the upwind side of the jet is suppressed. Meanwhile, due to the momentum injection effect of the plasma actuation, the streamwise velocity in the reverse flow region is enhanced and the size of the crossflow separation vortex pair downstream of the cooling hole is reduced. Furthermore, the plasma actuation weakens the strength of the kidney shaped vortex and prevents the jet from lifting off the wall. Therefore, the centerline film cooling efficiency rises with increasing the plasma actuation strength, and it is improved by 55% at most when the plasma actuation strength is 10.