Computational study of a small rotor at hover using CFD and UVLM

Performance of small rotors is a subject of interest due to increased use of Unmanned Aerial Vehicles (UAVs). In the present paper, numerical simulations of a small rotor commonly used in quadcopters were performed in hover flight. Computational Fluid Dynamics (CFD) and Unsteady Vortex Lattice Method (UVLM) were used and compared. CFD simulations were conducted with the commercial software Fluent ANSYS v17 using the Multiple Reference Frame (MRF) model. In UVLM, a model based on a viscosity dependent growth of the core of the tip vortex was used to account for viscous effects. The wake structure, pressure coefficient distribution on the rotor surface, thrust and torque coefficients obtained by different methods are compared in the paper. Results from flight tests are used to validate thrust and torque predictions. The difference in the prediction of the thrust coefficient between the computational methods is less than 9%. Both methods overestimate the thrust by 3% and 12% for CFD and UVLM respectively with respect to the flight test results.