A new approach for modeling combustion instabilities using acoustic energy conservation is proposed. This approach allows the flexibility to calculate contributions from amplification and/or attenuation across all frequencies, rather than predicting eigenmodes. It is likely that such a direct acoustic energy approach could be of benefit in determining the susceptibility of all frequencies to growth or decay as operating conditions in a gas turbine change. This approach may also give designers a method for improving passive damping in the initial design phase, with the ability to scan various frequencies and investigate the susceptibility to oscillatory instability at different operating conditions. A linear model, including linear approximations to nonlinear processes, is introduced whereby the mechanisms contributing to amplification and damping of acoustic energy are assessed independently to find a net amplification coefficient, a reciprocal time (or a rate). Stability for each frequency is assessed by examining a ratio between amplification and damping. It is anticipated that this effort may provide a useful new perspective on and enhanced prediction capability for combustion oscillatory instabilities.
An Acoustic Energy Approach to Modeling Combustion Oscillations
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Ibrahim, ZM, Williams, FA, Buckley, SG, & Lee, JCY. "An Acoustic Energy Approach to Modeling Combustion Oscillations." Proceedings of the ASME Turbo Expo 2006: Power for Land, Sea, and Air. Volume 1: Combustion and Fuels, Education. Barcelona, Spain. May 8–11, 2006. pp. 77-86. ASME. https://doi.org/10.1115/GT2006-90096
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