Nonlinear pressure-heat release transfer function measurements in a premixed combustor

Lieuwen, Tim; Neumeier, Yedidia

doi:10.1016/s1540-7489(02)80017-7

Cited by 101 publications

(38 citation statements)

References 9 publications

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“…Third, the main difficulty in building network acoustic models is to determine the response of individual burners [35][36][37][38][39]. The present results show that this response is the response of a burner submitted to an axial flow rate perturbation.…”

Section: Individual Burner Transfer Functionmentioning

confidence: 76%

Large Eddy Simulation of self excited azimuthal modes in annular combustors

Staffelbach

Gicquel

Boudier

et al. 2009

Proceedings of the Combustion Institute

280

133

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While most academic set ups used to study combustion instabilities are limited to single burners and are submitted mainly to longitudinal acoustic modes, real gas turbines exhibit mostly azimuthal modes due to the annular shape of their chambers. This study presents a massively parallel Large Eddy Simulation (LES) of a full helicopter combustion chamber in which a self-excited azimuthal mode develops naturally. The whole chamber is computed from the diffuser outlet to the High Pressure Stator nozzle. LES captures this self-excited instability and results (unsteady pressure RMS and phase fields) show that it is characterized by two superimposed rotating modes with different amplitudes. These turning modes modulate the flow rate through the fifteen burners and the flames oscillate back and forth in front of each burner, leading to local heat release fluctuations. LES demonstrates that the first effect of the turning modes is to induce longitudinal pulsations of the flow rates through individual burners. The transfer functions of all burners are the same and no mechanism of flame interactions between burners within the chamber is identified.

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Section: Individual Burner Transfer Functionmentioning

confidence: 76%

Large Eddy Simulation of self excited azimuthal modes in annular combustors

Staffelbach

Gicquel

Boudier

et al. 2009

Proceedings of the Combustion Institute

280

133

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“…Experimentally, several studies [14,15,5,6,16,11,17,18,19,20] have been conducted to determine the flame models needed for stability analysis. Recent examples of this include Noiray et al [9], who experimentally measured the FDF of an unconfined laminar burner; on combining with an acoustic model they obtained limit cycle predictions in excellent agreement with experiments.…”

Section: Introductionmentioning

confidence: 99%

Simulation of the flame describing function of a turbulent premixed flame using an open-source LES solver

Han

Morgans

2015

Combustion and Flame

103

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Numerical simulations were used to characterise the non-linear response of a turbulent premixed flame to acoustic velocity fluctuations. The test flame simulated was the bluff body stabilised flame which has been the subject of a detailed experimental study (Balachandran et al., 2005, Combustion & Flame). Simulations were performed using Large Eddy Simulation (LES) via the open source Computational Fluid Dynamics (CFD) software, Code S aturne, with combustion modelled by combining a Flame Surface Density (FSD) method with a fractal approach for the wrinkling factor. The cold flow field and the unforced reacting flow were used for preliminary code validation. In order to characterise the non-linear response of the unsteady heat release rate to acoustic forcing, a harmonically varying velocity fluctuation, for which both the forcing frequency and normalised forcing amplitude were varied, was imposed. The flame response was characterised via a Flame Describing Function (FDF), also known as a nonlinear flame transfer function, for which the gain and phase shift depend on forcing amplitude as well as forcing frequency. The response at four frequencies was compared to experimental data in detail, confirming that the LES results captured both the qualitative flame dynamics and the quantitative response of the heat release rate with very reasonable accuracy. The full FDF was then obtained across more frequencies, again showing a good fit with the experimental data, other than for a slight under-prediction in gain, most probably due to neglecting the effect of wall heat loss and the effect of combustion modelling. The agreement was significantly better than has been obtained previously for this test case using numerical simulations. Finally, it was found that increasing combustor length had little affect on the flame response, which may prove useful for future long combustor stability and limit cycle analysis. This work thus confirms that LES, in this case via the open source Code S aturne, provides a useful tool for characterising the response of lean premixed turbulent flames.

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“…Because of the complexity of combustion dynamics, harsh conditions, high noise levels, and lack of adequate sensing apparatus, an analytical form is not yet available. The heat released from combustion is most frequently modeled as a function of acoustic velocity that contains a saturation like quality as in [1,3,19,20,21]. With this in mind we denote the heat release contribution as:…”

Section: Heat Releasementioning

confidence: 99%

Passive Control of Limit Cycle Oscillations in a Thermoacoustic System Using Asymmetry

Eisenhower

Hagen²,

Banaszuk³

et al. 2008

Journal of Applied Mechanics

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In this paper we investigate oscillations of a dynamical system containing passive dynamics driven by a positive feedback and how spatial characteristics (i.e. symmetry) affect the amplitude and stability of its nominal limit cycling response. The physical motivation of this problem is thermoacoustic dynamics in a gas turbine combustor. The spatial domain is periodic (passive annular acoustics) which are driven by heat released from a combustion process, and with sufficient driving through this nonlinear feedback a limit cycle is produced which is exhibited by a traveling acoustic wave around this annulus. We show that this response can be controlled passively by spatial perturbation in the symmetry of acoustic parameters. We find the critical parameter values that affect this oscillation, study the bifurcation properties, and subsequently use harmonic balance and temporal averaging to characterize periodic solutions and their stability. In all of these cases, we carry a parameter associated with the spatial symmetry of the acoustics and investigate how this symmetry affects the system response. The contribution of this paper is a unique analysis of a particular physical phenomena, as well as illustrating the equivalence of different nonlinear analysis tools for this analysis.

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Nonlinear pressure-heat release transfer function measurements in a premixed combustor

Cited by 101 publications

References 9 publications

Large Eddy Simulation of self excited azimuthal modes in annular combustors

Large Eddy Simulation of self excited azimuthal modes in annular combustors

Simulation of the flame describing function of a turbulent premixed flame using an open-source LES solver

Passive Control of Limit Cycle Oscillations in a Thermoacoustic System Using Asymmetry

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