An investigation of drone propeller noise generation in a turbulent wake

Abstract

Unmanned aerial vehicles (UAVs) are becoming popular as they can be used in a range of applications including surveillance, delivery, agriculture, aerial photography, and search and rescue. This paper presents an experimental study to characterise the effect of turbulent inflow disturbance on the noise generated by a drone propeller using a low-noise, open-jet anechoic wind tunnel facility at UNSW. Advanced precision composites (APC) two-bladed, 12-inch rotors were tested at rotational speeds between 4000 and 8000 RPM at a freestream velocity of 15 m/s. The inflow disturbance upstream of the propeller is the wake of a NACA0012 profile wing to which the propeller is mounted. Hot-wire anemometry has been used to characterise the wake of the strut. The turbulence intensity, mean velocity, and turbulence length scale is calculated to characterise the turbulence ingested by the propeller. Acoustic measurements have been taken with multiple microphones to study the sound directivity and noise radiation of the propeller. A load cell is used to measure the torque and thrust produced by the propeller. This experimental program aims to characterise the wake profile ingested by the propeller and examine the associated noise generation.