Low-Noise Ducted Propellers

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Group Design Project
The design of a ducted propeller for a small UAV, which produces low noise levels whilst maintaining aerodynamic performance
Group Members
Sudeep Ale, Harry Bartley, Freya Malcher, Andrew Nesbitt, Dilan Neumann, Paba Senadheera, Edgar Svazas, Michael Symmonds

Supervisors
Professor Phil Joseph

Recent expansion of the use of Unmanned Aerial Vehicles (UAV) has resulted in noise concerns, especially around residential areas. With companies such as Amazon developing small UAVs to deliver goods to customers’ homes, the concern has a potential to become an important problem in the near future.

Shrouding UAV propellers has the potential to reduce the noise produced whilst also increasing safety. Therefore, this project investigated the effects of changing various duct and propeller parameters on noise level.

Duct and propeller designs were created in Solidworks before being 3D printed at the University Design Workshop. The noise from the design configurations was then measured in the Large Anechoic Chamber using a semi-circular array of microphones. The thrust from each configuration was also measured to determine its aerodynamic performance.
The project found that increasing the number of blades of the propeller and their pitch (angle of blade relative to oncoming air flow) meant that the propeller could be run at a lower speed, reducing the noise produced for a maintained thrust level. Placing the propeller further away from the stators in the duct also reduced the sound produced by the configuration whilst maintaining the thrust produced.

The ‘optimal’ design configuration consisted of a four bladed propeller (with increased pitch) and a duct with seven stators leaned away from the tips of the propeller blades.

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