Improved design for flutter free of fan rotor blade

Through aeroelastic stability prediction by energy method in original scheme of a two-stage transonic fan, the geometric modeling of aeroelastic unstable rotor was modified to improve the aeroelastic stability. Through comparative analysis of the geometric modeling, aerodynamic performance, vibration characteristic and aeroelastic stability of original and modified schemes, it showed that the minimum modal aerodynamic damping ratio of modified scheme increased from -146 to 183, eliminating the flutter risk, while the aerodynamic performance of the fan was kept unchanged and the modification to the original scheme was small. Increasing thickness and chord length can increase aeroelastic stability of blade at corresponding radial position, making it an effective means to improve flutter; however, attention should be paid to the change of aerodynamic performance. With the same reduction of channel blockage margin, adjustment of thickness distribution is the best way to improve aeroelastic stability.