Intrinsic thermoacoustic instability of premixed flames

Emmert, Thomas; Bomberg, Sebastian; Polifke, Wolfgang

doi:10.1016/j.combustflame.2014.06.008

Cited by 96 publications

(88 citation statements)

References 34 publications

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“…As noted by Emmert et al [3] this mode is quite unusual in thermoacoustics since it is obtained in a situation where acoustic losses at the burner's ends are maximum (anechoic terminations). The period of the first ITA mode is twice the flame delay and is not linked to any acoustic mode of the duct.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…However, recent theoretical studies [2,3] and experiments [4] suggest that, even in an anechoic environment, thermoacoustic instabilities may exist. These modes are called here Intrinsic Thermo-Acoustic (ITA) modes because they do not require any acoustic feedback from the boundaries of the burner to exist 1 .…”

Section: Introductionmentioning

confidence: 99%

“…This is the subject of this paper. In Section 2, the theoretical derivation of ITA modes is recalled, based on the work of Hoeijmakers et al [2] and Emmert et al [3], and further emphasis is given on the key parameters controlling this instability. Section 3 presents the numerical strategy to capture intrinsic thermoacoustic instabilities, and details are given on the laminar premixed flame setup used in this study.…”

Section: Introductionmentioning

confidence: 99%

“…ITA modes have been predicted theoretically and observed experimentally [2][3][4]. Analyzing them using Direct Numerical Simulation (DNS) is an obvious next step [8].…”

Section: Introductionmentioning

confidence: 99%

“…, Emmert et al 2015 suggest that thermoacoustic modes can appear in combustors with anechoic terminations, which have no acoustic eigenmodes. These modes, called here Intrinsic ThermoAcoustic (ITA), can be predicted with simple theoretical arguments, but have been ignored for a long time.…”

mentioning

confidence: 99%

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DNS of Intrinsic ThermoAcoustic modes in laminar premixed flames

Courtine

Selle

Poinsot

2015

Combustion and Flame

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. , Emmert et al. 2015 suggest that thermoacoustic modes can appear in combustors with anechoic terminations, which have no acoustic eigenmodes. These modes, called here Intrinsic ThermoAcoustic (ITA), can be predicted with simple theoretical arguments, but have been ignored for a long time. They are reproduced in this paper using Direct Numerical Simulation (DNS) of a laminar premixed Bunsen type flame. DNS results and theory are compared showing very good agreement in terms of both frequency and mode structure. DNS confirms that the frequency of ITA modes does not depend on any acoustic characteristic of the burner. Based on a numerical evaluation of the Flame Transfer Function, stability limits of ITA modes predicted by theory are also recovered in the DNS with reasonable accuracy. Finally, DNS is used to analyze the mechanisms of ITA modes.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…ITA modes have been predicted theoretically and observed experimentally [2][3][4]. Analyzing them using Direct Numerical Simulation (DNS) is an obvious next step [8].…”

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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DNS of Intrinsic ThermoAcoustic modes in laminar premixed flames

Courtine

Selle

Poinsot

2015

Combustion and Flame

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Parameter estimation of two coupled oscillator model for pure intrinsic thermo-acoustic instability

2023

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A nonlinear phenomenological model of two coupled oscillators is proposed, which is able to describe the rich nonlinear behaviour stemming from an unstable pure intrinsic thermo-acoustic (ITA) mode of a simple combustion system. In an experimental bifurcation analysis of a pure ITA mode, it was observed that for increasing mean upstream velocity the flames loose stability through a supercritical Hopf bifurcation and subsequently exhibit limit cycle, quasi-periodic and period-2 limit cycle oscillations. The quasi-periodic oscillations were characterised by low frequent amplitude and frequency modulation. It is shown that a phenomenological model consisting of two coupled oscillators is able to reproduce qualitatively all the different experimentally observed regimes. This model consists of a nonlinear Van der Pol oscillator and a linear damped oscillator, which are nonlinearly coupled to each other. Furthermore, a parameter estimation of the model parameters is conducted, which reveals a good quantitative match between the model response and the experimental data. Hence, the presented phenomenological dynamical model accurately describes the nonlinear self-excited acoustic behaviour of premixed flames and provides a promising model structure for nonlinear time-domain flame models.

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