In this paper,a predictor-corrector with 2nd-order backward difference(PC2B) time accurate free wake algorithm with explicit modification is formulated to investigate the rotor unsteady aerodynamic characteristics.As the rotor free wake equation possesses the characteristics of non-linearity,its solutions are susceptible to numerical instability.The modified equation of a different format is derived to investigate the accuracy and the numerical stability of the modified PC2B algorithm,and the stability and ...