Performance evaluation and comparison of dynamic inflow models for rotorcraft simulation

In this paper, well-known inflow models commonly used in rotorcraft simulations are applied to a blade element rotor model and compared with the isolated rotor wind tunnel tests of the main rotor of the S-76 helicopter in trimmed conditions. The paper provides side-by-side comparisons of steady state power estimations, collective blade angles, lateral cyclic, longitudinal cyclic inputs and coning angles in hover and forward flight trim conditions, when uniform inflow, linearly distributed inflow with Payne's coefficient, Pitt-Peters inflow model and Peters-He inflow model with higher harmonics are used. In addition, the differences in side and drag forces are shown in forward flight, when different inflow models are used. Inflow and angle of attack distributions over the rotor disk are compared at various flight conditions. Concluding remarks on the observed differences are given.