Helicopter Free Wake Prediction of Complex Wake Structures Under Blade-Vortex Interaction Operating Conditions

A free wake method for helicopter rotor application is described which removes many simplifying and limiting assumptions concerning the structure of the rotor wake geometry. In this method the complete wake surface is modeled using a vortex lattice structure. The method was successfully applied to both a main rotor and a tail rotor operating under Blade-Vortex Interaction conditions. The analysis predicted complex multiple tip vortex-like structures which have been observed experimentally for the tail rotor conditions studied.