Computational study of wake interaction in quadcopter unmanned aerial vehicle

Abstract

In the present study, the effects of the separation distance between rotors on the aerodynamic performance and wake structure of small size UAV were investigated. Numerical simulation of DJI Phantom 2 UAV model in hover flight has been carried out using nonlinear vortex lattice method with vortex particle method. Calculations for quadcopter configuration with various separation distances were compared with isolated rotor case to study the wake and flow structures of multi-rotor system. It is found that the average thrust coefficient decreases and the thrust coefficient begins to fluctuate dramatically in time, as the interval between rotors gets smaller. The wake geometry appears to radially shift toward the neighboring rotors, thus leading to strong wake-to-wake interaction. In addition, wake recirculation can be captured at the center of vehicle because of upwash flow induced by the wake vortices of adjacent rotors. As a results, both the hover performance and wake characteristics become highly unsteady at quadcopter configuration with small separation distance.