Prediction of Blade Vortex Interaction Aerodynamics for a Higher Harmonic Controlled Rotor

Abstract

An unsteady 3-D Panel Method is applied to compute the subsonic aerodynamics of a four blade rotor operating under Higher Harmonic Controlled (HHC) pitch input. The blades are of finite thickness and the full span free wake is simulated by a vortex lattice which evolves as the computation proceeds. Three flight conditions: Baseline, without HHC input, Minimum Noise and Minimum Vibration with 3-per-rev. HHC inputs are the subject of study. Predicted pressure distribution, chordwise and spanwise for all three cases is in fair agreement with wind tunnel results. Time history of pressure at selected chordwise and spanwise stations captures the basic trends of the experimental results. Blade Vortex Interaction Loci in rotor disc and tip vortex trajectories predicted are in good agreement with results obtained at ONERA and experiment. The shift of tip vortex trajectory with.