Numerical Study of Aerodynamic Performance of a Multirotor Unmanned-Aerial-Vehicle Configuration

Abstract

Numerical investigations into the aerodynamic performance and the mutual aerodynamic interactions between the rotors and a fuselage were conducted for a multirotor unmanned-aerial-vehicle configuration. For this purpose, time-accurate unsteady-flow calculations were performed by using a three-dimensional unstructured-mesh flow solver. The fluid motion was assumed to be governed by the three-dimensional, incompressible, Navier-Stokes equations. To handle the relative motion of the rotor blades, an overset-mesh technique was adopted. Numerical simulations were performed for a quadrotor unmanned aerial vehicle with fuselage in hover and in forward flight. To examine the effect of flow direction in forward flight, both diamond and square formations of the rotors were considered. It was observed that, in the case of hovering flight, the mutual aerodynamic interactions of the rotors induce slightly higher inflow than an isolated single rotor, and produce unsteady fluctuating-thrust variations. When the vehicle is in forward flight, the tip vortices and the downwash flow from upstream rotors strongly affect those at downstream by locally changing the thrust behavior. The mutual aerodynamic interactions between rotors also result in increased pitching and rolling moments of the vehicle. It was recommended that aerodynamic interactions between multiple rotors should be considered when designing the stability and attitude-control algorithms of multirotor unmanned-aerial-vehicle configurations.