Numerical Investigation of the Effect of Sinusoidal Pulsating Cooling Air on Film Cooling Effectiveness of Leading Edge, Pressure and Suction Side of a Turbine Blade

Film cooling is one of the most effective methods for protecting turbine blades from thermal overheating. For steady gas flow, the film cooling has been extensively investigated, but there is insufficient knowledge of how the pulsation affects the film cooling performance. In this study, the effects of air coolant injection with sinusoidal pulsations on temperature distribution and film cooling effectiveness of a turbine blade is numerically investigated. Cooling air is injected through the three plenums to leading edge, pressure and suction sides of the blade at five blowing ratios of 0.5, 0.75, 1, 1.5, 2, and 2.5 with frequency of 50Hz. Also, the effect of main flow Reynolds number on cooling performance is studied. Finite volume method was used to solve flow governing equations. Obtained results show that pulsating the blade cooling mass flow rate causes the size of counter vortex rotating pair to be varied, resulting in change of temperature distribution of the surface at each time steps. The averaged centerline pulsed film cooling effectiveness distribution is maximized on downstream of the injection hole of leading edge, pressure side and suction side at blowing ratio of 0.75, 0.5 and 1, respectively.