Numerical prediction of combustion instability limit cycle oscillations for a combustor with a long flame

Combustion and Flame ◽

10.1016/j.combustflame.2017.06.018 ◽

2017 ◽

Vol 185 ◽

pp. 28-43 ◽

Cited By ~ 27

Author(s):

Jingxuan Li ◽

Yu Xia ◽

Aimee S. Morgans ◽

Xingsi Han

Keyword(s):

Limit Cycle ◽

Combustion Instability ◽

Numerical Prediction ◽

Limit Cycle Oscillations

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Prediction of combustion instability limit cycle oscillations by combining flame describing function simulations with a thermoacoustic network model

Combustion and Flame ◽

10.1016/j.combustflame.2015.06.020 ◽

2015 ◽

Vol 162 (10) ◽

pp. 3632-3647 ◽

Cited By ~ 75

Author(s):

Xingsi Han ◽

Jingxuan Li ◽

Aimee S. Morgans

Keyword(s):

Limit Cycle ◽

Network Model ◽

Combustion Instability ◽

Limit Cycle Oscillations ◽

Describing Function ◽

Flame Describing Function

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Feedback Control of Self-Sustained Nonlinear Combustion Oscillations

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2015-42126 ◽

2015 ◽

Author(s):

Xinyan Li ◽

Dan Zhao

Keyword(s):

Heat Source ◽

Limit Cycle ◽

Gas Turbines ◽

Acoustic Pressure ◽

Sliding Mode ◽

Mode Selection ◽

Combustion Instability ◽

Source Model ◽

Sliding Mode Controller ◽

Limit Cycle Oscillations

Detrimental combustion instability is unwanted in gas turbines, aeroengines and rocket motors. It is typically generated due to the dynamic coupling between unsteady heat release and acoustic pressure. To prevent the onset of combustion instability or dampen large-amplitude oscillations, the coupling must somehow be interrupted. In this work, we design and implement a sliding mode controller and observer to mitigate self-sustained combustion oscillations in an open-ended thermoacoustic system. An acoustically compact heat source is confined and modeled by using a modified form of King’s Law. Coupling the heat source model with a Galerkin series expansion of the acoustic pressure provides an approach to evaluate the performance of the sliding mode control. The thermoacoustic systems with different numbers of eigenmodes and actuators are considered. It is found that self-sustained limit cycle oscillations can be successfully produced from small perturbations in the thermoacoustic systems when the actuators are not actuated. Meanwhile, the system we modeled can be proved to be controllable and observable. In order to gain insight on the thermoacoustic mode selection and triggering, the acoustical energy exchange between neighboring eigenmodes are studied and discussed. As the controller-driven actuators are actuated, the limit cycle oscillations are quickly dampened. And both thermoacoustic systems are stabilized. The successful demonstration indicates that the sliding mode controller can be applied to stabilize unstable thermoacoustic systems, even with multiple eigenmodes.

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