RESEARCHERS FIND THAT PROPELLERS ARE LOUDER OVER GROUND

For the very first time the effects of the ground on propeller noise have been measured experimentally by researchers in the Aeroacoustics research team at the University of Bristol

- LIAM HANSON

In findings, published in the Journal of Sound and Vibration, the team found clear differences in the noise characteristics of propellers when over ground, known as 'ground effect', compared to when operated normally. They noted an overall noise increase when measuring at angles above the ground, with hydrodynamic and acoustic interaction effects being a key factor to the overall noise trends. It is hoped this research, tested in the National Aeroacoustic Wind Tunnel facility, can inform strategies to reduce the noise of aircraft while taking off or landing, by either changing the design of the landing pads or by changing the design of proposed aircraft architectures.

Lead author Liam Hanson explained: "In light of the need for greener aviation, there has been a push in the aviation industry to develop electrified aircraft. "There is a lot of potential benefits from electric aircraft which have been identified by a variety of companies worldwide, including all of the major aircraft manufacturers." However, if urban air services such as on demand air taxis are to become a reality within city limits, engineers must tackle the issue of sound pollution, generated by propellers.