CUED Publications database

Vortices, sound and flames - a damaging combination

Dowling, AP (2000) Vortices, sound and flames - a damaging combination. Aeronautical Journal, 104. pp. 105-116. ISSN 0001-9240

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The interaction between vortices, sound and combustion can lead to self-excited oscillations of such large amplitudes that structural damage is done. These occur because any small unsteadiness in the rate of combustion is a source of sound, generating pressure and velocity fluctuations. However, the velocity fluctuations perturb the flame, thereby altering the instantaneous rate of heat release. Instability is then possible because while acoustic waves perturb the combustion, the unsteady combustion generates yet more sound! Combustion oscillations can occur in afterburners and at idle in conventional aeroengine combustors. Lean premixed, prevapourized technology has tremendous potential to reduce NO x emissions, but is proving highly susceptible to self-excited oscillations. An overview of the physics of the interaction between vortices, sound and flames is presented, and illustrated by examples of instability in generic premixed ducted flames and in aeroengine combustors. The potential for both passive and active control is discussed.

Item Type: Article
Divisions: Div A > Fluid Mechanics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:28
Last Modified: 05 Sep 2017 01:51