Sounding out quieter aircraft
University of Adelaide researchers are working towards the reduction of aircraft noise by controlling the noise generated by air flowing over the aircraft surfaces.
Reducing "trailing edge aerodynamic noise" is the next research focus for Professor Colin Hansen, who has been awarded the British Institute of Acoustics' premier medal, the Rayleigh Gold Medal, for his outstanding contribution to acoustics.
Professor Hansen leads the School of Mechanical Engineering's Acoustics, Vibration and Control Group and, for many years until recently, was Head of School.
He and research colleagues Dr Con Doolan and Dr Laura Brooks are jointly researching the mechanics of noise generation on the surface of aircraft wings, and will investigate methods of actively reducing the noise.
Active control - as opposed to passive control or soundproofing - involves the introduction of a secondary sound field to suppress or cancel an unwanted noise.
Trailing edge noise is caused by air turbulence over the edge of the aeroplane wing. They plan to reduce this noise by actively disrupting the pattern of turbulence by creating artificial vibration on the wing surfaces.
"Now that aircraft jet engines have become relatively quiet, further reduction of the total noise on landing and low-level flight will require reduction of this aerodynamic noise generated by all the surfaces of the aircraft in the air flow," said Professor Hansen.
"If we can get aircraft quiet enough for landing, there are obvious implications for flight curfews."
Experiments conducted in the University's anechoic acoustic test chambers on model air foils will be used to develop and optimise an active noise control system involving the use of small devices (actuators) bonded to the wings and driven by a complex control system.
Over the past 20 years at the University of Adelaide, Professor Hansen has built his reputation as a world leader in the field of active noise and vibration control, winning more than $6 million in research grants and a variety of international awards and fellowships. He also has been active as a consultant on problems including noise and vibration control, failure analysis, accident analysis and mechanical design.
He has written or co-authored 10 books and eight book chapters and edited two books in his field plus more than 250 papers in refereed journals and international conference proceedings.
His book Active control of sound and vibration, co-authored with Scott Snyder, has been a key text for the field, as has his Engineering Noise Control, with David Bies, now on its fourth edition.
The Institute of Acoustics said Professor Hansen's name was "known to almost everyone who works with noise control for his series of ever-expanding editions of Engineering Noise Control".
"Dog-eared copies of earlier editions grace the shelves of a large proportion of the world's engineering acousticians.
"We in the international acoustics community are privileged to have among us such a versatile, inventive and industrious colleague who, through his research, supervision of students and extensive publications, has made important contributions to the development of engineering acoustics," the Institute's citation said.
Story by Robyn Mills