Sweeping Jet Film Cooling Over the Suction Surface of Hp Turbine NGV With Forward and Reversed Hole Configurations

Abstract Film cooling is essential for the proper functioning and desired operation of modern gas turbine engines. In this study, numerical investigations were performed to study the effects of forward and reversed hole configurations on the performance of sweeping jet film cooling. A comparison of film cooling performance is presented for sweeping jet and straight jet over a flat plate with both forward and reversed configurations. Operating parameters were maintained for matching the real engine conditions with freestream Reynolds number of 1 × 106 and favorable pressure gradient of HP turbine NGV suction surface imposed on the flat plate. The blowing ratio (M) was varied in the range of 0.35 to 2.0, at a density ratio (DR) of 1.8 with an injection angle of 30° for both the steady and sweeping jet for each configuration. The results indicated that the sweeping jet with a reversed configuration provides the highest coolant coverage and the straight jet with a forward configuration provides the highest cooling effectiveness out of all the configurations. The averaged adiabatic film cooling effectiveness reduces with the blowing ratio for all the configurations except for the straight jet in the forward configuration. Sweeping jet and reversed configuration both are prone to higher diffusion of coolant stream as compared to straight jet and forward configuration comparatively. Instantaneous CRVP (contra-rotating vortex pairs) is detected in sweeping jet with a reversed hole configuration at a higher blowing ratio (M = 2.0)