The unsteady flow field of the same transonic fan at both transonic and subsonic operating conditions was simulated numerically.The periodic unsteady aerodynamic forces of the flow field at both transonic and subsonic operating conditions were analyzed by Fourier Transform Algorithm

and then compared to obtain the unsteady aerodynamic characteristics at tansonic operating condition.The forced response of the rotor blade was analyzed with ANSYSby using the method of transient response analysis.The forced response of the rotor blade between transonic and subsonic operating conditions was analyzed comparatively to find out the characteristics of the forced response.