Numerical simulation of rotor flow in hover

Aerodynamic loads on a multibladed helicopter rotor in hovering flight are calculated by solving the unsteady three-dimensional Reynolds-averaged Navi er-Stokes equations. It is well known that, because of the numerical diffus ion, the rotor-wake effects cannot be properly simulated by a Navier-Stokes calculation with a moderate grid number, which leads to the calculated suc tion pressures higher than the experimental values. The rotor-wake effects are then accounted for by the correction of local geometric angle of attack according to a free-wake modeling in addition to an empirical modification for the tip flow effects. The validity and efficiency of the present metho d have been verified by the comparisons between numerical results and exper imental data.