Effects of Plasma Actuation on Film Cooling Characteristics

Large eddy simulations were conducted to investigate the influences of saw-tooth plasma actuator on the film cooling efficiency and aerodynamic loss of cylindrical and fan-shaped holes. The results show that thanks to the momentum injection effect of plasma actuation the boundary layer fluid accelerates, and thus the coolant extends further downstream. Moreover, the anti-kidney shaped vortex induced by the saw-tooth plasma actuator effectively weakens the strength of kidney shaped vortex, then the mixing process between coolant and crossflow is suppressed, the centerline and lateral-averaged film cooling efficiency of fan-shaped hole are therefore increased 130% and 300% in comparison to the cylindrical hole without plasma actuation, the mixing loss generated by the kidney shaped vortex is also greatly decreased. Since the plasma actuation strengthens the blocking effect of crossflow on the coolant, the flow loss in cooling holes increases and becomes an important source of the total pressure loss. Furthermore, due to the plasma actuation, the entropy creation of cylindrical hole is increased by 26%, but the entropy creation of fan-shaped hole is decreased by 41%.