Numerical simulation of unsteady flow past autorotating rotor in gyroplane level flight

Two distinguishing features, inclining backward rotor disk and unpowered rotor, make fluid field of autorotating rotor in gyroplane level flight different from helicopter rotor in forward flight. Unsteady flow past autorotative rotor in gyroplane level flight is time-accurately simulated by solving URANS based on multi-block structured grid. The methods of the sliding mesh and the Full-Approximation Storage Multigrid are utilized. Autorotating speed, the solution of the BET model of gyroplane level flight, is assigned to an initial condition of unsteady numerical simulation after fine tune. At several advanced ratios, the agreement between simulation results and Eugene E. Niemi´s wind tunnel test data is good. The aerodynamics of the autorotative rotor is investigated by using these numerical results.