Evaluation of Adjoint Optimized Hole - Part II: Parameter Effects on Performance

In a previous study from our laboratory, a computational adjoint based optimization method was used to design shaped film cooling holes fed by internal co-flow and cross-flow channels. The associated RANS computations predicted that the holes optimized for use with cross-flow (X-AOpt) and co-flow (Co-AOpt) would increase adiabatic effectiveness significantly compared to a baseline 7-7-7 shaped hole. Experimental validations of these performance predictions are presented in companion paper (Gutierrez et al., 2022). Although the experimental values were significantly lower than the computational predictions, the adiabatic effectiveness for the adjoint optimized holes was measured to be noticeably higher than that for the baseline 7-7-7 shaped hole. Specifically, the X-AOpt hole was 75% higher and the Co-AOpt hole was 30% higher in terms of peak performance when P/D effects were accounted for. In this study, the effects of various key parameters on the performance of the adjoint optimized holes were determined. For these experiments the internal channel velocity ratios ranged from VRc = 0.2 to 0.4, both co-flow and counter-flow conditions were used, and the density ratio ranged from DR = 1.2 to 1.8. These provided a quantification of the performance of the adjoint optimized holes over a wide range of operating conditions encompassing engine relevant conditions. Adiabatic film effectiveness measurements and thermal field measurements are made to understand the performance variations and to compare with 7-7-7 SI (sharp inlet).