Experimental and numerical investigation on subsonic film cooling performance with subregional strategy

Subsonic film cooling performance is investigated, applying an experimental research method as the main approach with numerical simulation supplemented. The linear turbine cascade experiment of film cooling is designed and arranged to validate the subregional strategy, which adds different compound angles to the film cooling holes based on the extents of secondary flow. The strategy is applied to four types of blade models and all cases of the experiment are conducted under subsonic conditions with a high-temperature difference, enabling the acquisition of both film cooling and aerodynamic data. The impact of subregional strategy on film cooling and aerodynamic performance is progressively analyzed with mechanisms gradually clarified. Film Cooling Effectiveness, Total Pressure Loss Coefficient and Isentropic Mach Number are selected and gathered as analyzing parameters. According to the results at design incidence, subregional strategy of film cooling is experimentally and numerically proved to improve Film Cooling Effectiveness in all cases, which also brings mass flow rate fluctuation in the coolant cavity. Less loss generation is confirmed in certain cases with subregional strategy. By suppressing the passage vortex and counter-rotating vortex separately, loss can be cut down while providing better film cooling on different positions of the blade surfaces.