In order to analyze the aerodynamic characteristics of airfoil under the condition of unsteady free stream velocity

the movingembedded grid method was employed to simulate the fluctuating velocity. Based on this method

the URANS(unsteady Reynoldsaveraged Navier-Stokes) equations coupling with the implicit scheme of LU-SGS(lowerupper symmetric Gauss-Seidel) was used to simulate the unsteady aerodynamic characteristics of the SC1095 airfoil under the condition of steady angle of attack with unsteady free stream velocity and under the condition of unsteady angle of attack with unsteady free stream velocity. It was discovered by comparing the calculated results that the unsteady characteristics

including hysteresis phenomenon

fluctuation and leading edge vortex induced by the unsteady free stream velocity

were observed under these conditions

and the unsteady characteristics were more obvious as the fluctuating velocity increased. By comparing the characteristics of airfoil at different basic velocities

it was found that the peaks of aerodynamic force curves enlarged as the basic velocity increased

and the unsteady vortex formed more early when the angle of attack increased. Considering the actual work environment of helicopter rotor

the aerodynamic loads of airfoil under dynamic stall were weakened at the large angle of attack and enhanced at the small angle of attack under the unsteady free stream velocity condition.