Multi-objective optimization of B-spline parameterized film holes: Cooling effectiveness, thermal stress and flow resistance

Film cooling is widely used in turbine blades and combustors, serving as an indispensable key technology for gas turbines and aero-engines. Previous research on film cooling optimization has predominantly adopted single-objective approaches centered exclusively on cooling effectiveness. Multi-objective optimization of film cooling holds substantial engineering value for practical applications and manufacturing implementation. Straight film cooling holes, as a classic configuration, offer distinct advantages in manufacturability and cost efficiency. This study generates straight holes of arbitrary shapes with identical cross-sectional areas using B-spline curves. A hybrid surrogate model integrating CGAN and MLP is employed to rapidly predict cooling effectiveness, thermal stress, and flow resistance. Optimized holes are subsequently obtained via MIGA. Relative to the cylindrical hole, Optimized Hole 1 achieves a 15.1% increase in average cooling effectiveness and a 6.8% reduction in stress concentration factor (SCF), while Optimized Hole 2 demonstrates a 29.8% enhancement in average cooling effectiveness and a 20.1% decrease in SCF. In terms of aerodynamic performance, the cylindrical hole exhibits a higher discharge coefficient, whereas the optimized holes demonstrate a lower total pressure loss coefficient.