CUED Publications database

G-equation modelling of thermo-acoustic oscillations of partially-premixed flames

Semlitsch, B and Orchini, A and Dowling, AP and Juniper, MPJ (2017) G-equation modelling of thermo-acoustic oscillations of partially-premixed flames. International Journal of Spray and Combustion Dynamics, 9. pp. 260-276. ISSN 1756-8277

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Numerical simulations aid combustor design to avoid and reduce thermo-acoustic oscillations. Non-linear heat release rate estimation and its modelling are essential for the prediction of saturation amplitudes of limit cycles. The heat release dynamics of flames can be approximated by a Flame Describing Function (FDF). To calculate an FDF, a wide range of forcing amplitudes and frequencies needs to be considered. For this reason, we present a computationally inexpensive level-set approach, which accounts for equivalence ratio perturbations on flames with arbitrarily-complex shapes. The influence of flame parameters and modelling approaches on flame describing functions and time delay coefficient distributions are discussed in detail. The numerically-obtained flame describing functions are compared with experimental data and used in an acoustic network model for limit cycle prediction. A reasonable agreement of the heat release gain and limit cycle frequency is achieved even with a simplistic, analytical velocity fluctuation model. However, the phase decay is over-predicted. For sophisticated flame shapes, only the realistic modelling of large-scale flow structures allows the correct phase decay predictions of the heat release rate response.

Item Type: Article
Divisions: Div A > Fluid Mechanics
Div A > Energy
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:54
Last Modified: 10 Apr 2021 01:40
DOI: 10.1177/1756827717711405