Compressor Blade Shaping and Optimization Through Design Features Based on Free-Form Deformation

Abstract This paper describes the application of Free-Form Deformation method in the adjoint optimization of a highly loaded transonic axial fan, with the characteristic that parameterization procedures are closely related to design features of blade. This approach effectively parameterizes the compressor blade from the perspective of design elements, while ensuring high flexibility. Geometric constraints, such as maintaining the blade's thickness, are easily achieved. Using the efficient adjoint method, four optimizations are conducted separately for the blade profiles without and with stacking control, endwall region, and tip clearance of Rotor 35. Optimized designs are presented, followed by detailed flow analysis. Results show a significant performance improvement in the design condition in the first three optimizations. The adiabatic efficiency improved by 0.8% in blade profile optimization, 1.2% in profile with stacking optimization, and 0.5% in endwall optimization, while changes in mass flowrate and total pressure ratio were relatively small. The typical S-shape blade, blended blade, and end wall-type corner region were found during the automated search process of adjoint optimization. The shock wave, shock-induced boundary layer separation, and accumulation of boundary layer were also well controlled. Through this study, a personalized free-form deformation parameterization method for compressor design was proposed.