Engineering Research Seminar Series 4, 2011: Phase Prediction of Combustion Noise

Goh Chee Su, Department of Aeronautics, Imperial College London

Date: 2011-02-24
Time: 11:00 to 12:00
Venue: Classroom 9-3-05


Combustion noise is a significant contributor to aircraft noise. The unsteady combustion in gas turbine combustors generates both acoustic and entropy waves. The acceleration of the entropy waves at the combustor exit through the first stage of the turbine creates further acoustic fluctuations, known as indirect combustion noise. This research considers the flow through a convergent-divergent nozzle in order to predict the transmitted response of the nozzle to both acoustic and entropy disturbances. An asymptotic analysis is described, leading to novel predictions for the phase of the acoustic transmission, which are valid for choked nozzles and at low frequencies. The results have been found to agree well with numerical simulations. These analytical expressions are only a function of the mean Mach number variation through the nozzle, and are well-suited to extend the acoustic modelling used in network or matrix thermoacoustic methods to include phase predictions.

About the Speaker

Goh Chee Su is an engineering graduate from the University of Cambridge who is currently working towards a Ph.D. with the Department of Aeronautics, Imperial College London. Prior to returning to academia, he was a consulting mechanical engineer with Shell Global Solutions International in The Netherlands (2004-2006), before being made responsible for the maintenance and operation of the gas turbine and compressor fleet on Shell U.K.'s Brent platforms as the Senior Rotating Equipment Engineer (2006-2008). Chee Su's current research interests include noise generated by jet engine combustors and how the interaction between acoustics and combustion may lead to thermoacoustic instabilities.