Reducing of Rotor-Airframe Interaction Noise in sUAS Using a Curved Support Rod

Small Unmanned Aerial Systems (sUASs), commonly referred to as drones or multirotors, typically utilize several rotors distributed throughout the airframe, allowing for a lower tip speed and additional maneuverability. Rotors are typically mounted to the sUAS with a support rod. The rotor blade operates in close proximity to the rod and, as a result, creates installation noise, sometimes referred to as Rotor-Airframe Interaction (RAI) noise. Unsteady deterministic noise is generated by the aerodynamic interaction between the rotor and rod that emits an acoustic impulse event each time the blade passes the rod. It has been observed that rapid changes in the potential flow field create impulsive changes in aerodynamic loading, which produce the impulsive acoustic noise emitted by the RAI.