Aerodynamic investigation of a drone propeller in cross-flow

Drones propellers operate in a transitional regime and may often experience high inflow angles. Such challenging conditions make the performance and the wake flow field dynamics difficult to be accurately predicted or simulated with computational methods. An experimental investigation is hence conducted on an isolated drone propeller, for different rotational speeds of the propeller and cross flow speeds. Considerable differences occur with respect to the hovering case and are discussed through the analysis of thrust and torque, along with the propeller’s wake topology investigated through planar particle image velocimetry (PIV). In the different cases considered, we infer a strong deflection of the wake development owing to the cross-flow. Furthermore, a compression of the wake shear layer is evidenced. A further analysis is carried out on the identification and characterization of the vortices shed from the blades tip. A particular focus is made on the computation of the mean trajectory, dimension and circulation.