Large eddy simulations of the turbine vane pressure side film cooling flows of cylindrical and fan-shaped holes with a saw-tooth plasma actuator

Large eddy simulations were conducted to study the film cooling performance of turbine pressure side with cylindrical hole, fan-shaped hole and saw tooth plasma actuator (STPA). A detailed analysis of the time-averaged film cooling flows was made. The results showed that the dual control effects of the combined design of the fanshaped hole with the STPA reduced the exit momentum and blowing off effect of the jet flow, remaining the jet flow close to the pressure side. The combined design also effectively weakened the entrainment effects of counter rotating vortex pair (CRVP) and enlarged cooling film coverage. Therefore, the spanwise averaged cooling efficiency was improved more than 30% in comparison to the cylindrical hole, but the fan-shaped hole caused a 23.9% increase in aerodynamic loss, and the STPA had few additional aerodynamic losses. Subsequently, the instantaneous film cooling flows were analyzed, the combined design suppressed the evolution processes of the vortex rings in the near-hole region, and the coherent structures in the far downstream region were decreased in size, affecting the mixing process of coolant and gases. The CRVPs were noticeably elongated along the pressure side and moved downstream periodically over time. The present study highlighted the superiority of the combined design to improve the turbine vane cooling performance.