Publication on ProCap measurements on aerodynamics of hovering drones
Wake Characteristics of a Free-Flying Quadrotor Hovering in Uniform and Shear Inflows
The wake of a free-flying small quadrotor (DJI NEO) was measured under still air, uniform inflow, and vertical- and horizontal-shear inflow at the exit of an open-circuit wind tunnel. Sensor Tracking Velocimetry (STV) using the ProCap system combined a multi-hole probe with optical tracking to reconstruct three-component, time-averaged velocity fi elds and the mean pressure fi eld on multiple planes downstream and below the vehicle. In still air, four rotor jets merge into a combined downwash; a control-volume momentum balance yielded a mean thrust within 0.76% of the vehicle weight, supporting the accuracy of the reconstructed fi elds. In uniform inflow (U ∞ = 4.3ms −1 ), the wake is convected downstream and exhibits a pronounced counter-rotating vortex pair typical of a jet in crossflow. Under shear inflow, the wake becomes strongly asymmetric, with clear deflection and distortion of the dominant coherent structures. These results quantify the sensitivity of multirotor wakes to nonuniform inflow and demonstrate the potential of ProCap for rapid volumetric wake surveys.
