Aerodynamic characteristics of a quadrotor UAV in hovering mode*

In the present study, we investigate the aerodynamic characteristics of a quadrotor UAV in hovering mode by measuring the lift force and multiple two-dimensional velocity fields in the wake. The experiment is conducted at Re = 30,000 in a chamber large enough to neglect the ground effect, where Re is the Reynolds number based on the rotor chord length and the rotor-tip speed. The strength of the rotor-tip vortex shedding is asymmetric with respect to the rotor axis due to the rotor wake interaction, and the wake centerline of each rotor is inclined to the center of the UAV. The wake from each rotor moves closer to each other while traveling in the streamwise direction, and then is merged together inducing large fluctuations in the transverse velocity. In addition, the effect of the distance between rotors on the aerodynamic performance will be also discussed in the presentation.