Multi-Objective Aerodynamic and Aeroelastic Coupled Design Optimization Using a Fully Turbulent Discrete Adjoint Harmonic Balance Method

Abstract With increasing requirements for high-loading and high-efficiency turbomachines, blades become thinner and thinner and thus design optimizations considering both aerodynamic performances and aeroelastic stability become more and more necessary. In this study, a fully turbulent discrete adjoint harmonic balance (HB) solver is developed using algorithmic differentiation (AD), validated by a discrete linear solver, and then adopted to perform multi-disciplinary coupled design optimizations. To this end, a framework of multi-objective adjoint design optimizations is developed to improve both aerodynamic performances and aeroelastic stability of turbomachinery blades. This framework is divided into two steps including the aeroelastic design initialization and aerodynamic Pareto front determination. First, the blade profiles are optimized to improve the aeroelastic stability only and constrain the change of aerodynamic performances. Second, the optimized blade profiles in the first step are used as the initial ones and then further optimized with the objective function of aerodynamic parameters and the constraints of aeroelastic parameters. The effectiveness of the multi-objective design optimization method is demonstrated using the transonic NASA Rotor 67 subjected to a hypothetical vibration mode. The results show that the multi-objective adjoint design optimization method can improve not only aerodynamic performances but also flutter stabilization.