Aerodynamic performance improvement of a transonic axial compressor by swept and leaned rotors

To understand rotors axial sweep and tangential lean effects on transonic axial compressor NASA Rotor37 aerodynamic performance, a numerical study was carried out. Rotor stacking line was described by Bezier polynomials and optimized in axial and tangential direction separately and coupledly. The optimization problem was to achieve the maximum rotor isentropic efficiency at the design point, with a constraint on mass flow rate and pressure ratio. A technique based on concept of function approximation was developed for rotor performance evaluation. Steady and unsteady flow simulations across the rotor were completed to predict performance at various working conditions. It was found that both C shape and S shape stacking line helps to improve rotor efficiency and stall margin. The C shape swept and leaned rotor displays the best performance. The peak efficiency was increased 1.1%, peak total pressure ratio increased 1.6% and the absolute value of stall margin increased 2% compared to Rotor37. Shock wave and tip leakage flow were found to move downstream with less strength. The fluctuation of blade pressure and backflow near stall condition of Rotor37 were analyzed.