Performance assessment and optimization of three-dimensional hybrid slot-effusion jet cooling configuration of an annular combustor liner

In this study, the film cooling performance of a three-dimensional (3D) hybrid slot-effusion configuration and its advantages over a baseline pure 3D slot cooling are investigated in detail using both experimental and numerical investigations. The numerical model is validated by in-house experiments conducted on a hybrid cooling configuration with a 3D slot and staggered effusion array. Infrared thermography and hot wire anemometry are used in this study to analyze the thermal and flow fields. The cooling performance of pure 3D slot and hybrid configurations is compared under identical coolant consumption. The coolant mass flow ratio (MFR) determines the cooling behavior in hybrid cooling. At low MFRs, hybrid cooling is less effective than pure 3D slot cooling. In addition, it is observed that there exists an optimal MFR where hybrid cooling outperforms 3D slot cooling. Subsequently, the effect of key design variables on the cooling performance of the hybrid configuration is studied, and they are optimized at typical combustor operating conditions using a genetic algorithm coupled to a Kriging surrogate model. The optimal configuration is experimentally tested at laboratory conditions and compared with the baseline 3D slot configuration, and it is noted that there is a significant improvement in the cooling effectiveness. Additionally, the film cooling performance of the optimized configuration at combustor representative operating conditions of maximum BR of 2 shows an enhancement of 16% in area-averaged adiabatic effectiveness and a 60% reduction in the standard deviation of local adiabatic effectiveness as compared to the baseline 3D slot cooling.