Impact of Vortex – Wake Interference on Rotor Trim

Abstract

Rotors of vertical take-off and landing vehicles (main rotor, tail rotor, and propeller) are often subjected to in-teraction with vortices from other lifting devices, such as from preceding fixed-wing aircraft, rotorcraft, or wind turbines. Up to now most numerical investigations consider the interaction as independent of each other, i.e. the interacting vortex remains spacefixed without deformation due to the rotor, and the rotor wake remains unaffected by the external vortex. For the aerodynamics on the rotor blades this represents a conservative approach. In this paper the external vortex is considered as deflected by the rotor wake and immersed into its slipstream, which can have significant impact on the interaction aerodynamics and resulting blade motion, depending on the advance ratio. This topic is addressed in this paper.