Prediction of rotor flow for unmanned aerial system using nonlinear vortex lattice method

Abstract

Small scale of unmanned aerial vehicle (UAV) is becoming more important subject for next generation. In order to investigate the aerodynamics of the UAV, very low Reynolds number and slow flight velocity corresponding to its small scale should be considered. There were attempts to include the low Reynolds number effect into the conventional vortex lattice method (VLM) using table look-up, but location for induced velocity for the table look-up was ambiguous. The main purpose of the current study is to solve the ambiguity by introducing an equivalent lattice approach. An appropriate location for the approach is analyzed, and a nonlinear VLM with that approach is developed. Finally, it is validated in two flow cases of a fixed wing and a UAV propeller.