An investigation of drone propeller noise generation in a turbulent wake

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. As propeller noise can dominate the acoustic signature of a UAV, it is important to understand the noise generation of the propeller to permit widespread use of UAVs in our communities. This thesis first presents an experimental study to characterise propeller noise in a hybrid wind tunnel at UNSW. The facility consists of an anechoic chamber attached to a closed return, hardwalled aerodynamic tunnel via a Kevlar window to permit noise measurements. This setup is used to characterize propeller noise in both the streamwise and planarwise orientation. The effect of turbulent inflow disturbance on the noise generated by a drone propeller is also studied 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 3500 RPM and 5000 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 simulating a UAV in pusher configuration. Hot-wire anemometry is used to characterise the wake of the strut. The mean velocity, turbulence intensity, velocity spectra and turbulence length scale are 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 was also used to measure the torque and thrust produced by the propeller. The experimental program aims to characterise the wake profile ingested by the propeller and to examine the associated propeller noise generation.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2024

Author dc:creator

• Bian, Alex

• anzsrc-for: 401206 Fluid-structure interaction and aeroacoustics
• anzsrc-for: 4012 Fluid mechanics and thermal engineering

Statement dc:rights

• open access
• CC BY 4.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

en

Identifier

https://doi.org/10.26190/unsworks/31128

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/104864