Combustion Dynamics Validation of an Annular Reheat Combustor

Singla, Ghislain; Noiray, Nicolas; Schuermans, Bruno

doi:10.1115/gt2012-68684

Cited by 3 publications

(2 citation statements)

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“…Note that recently, high-frequency thermoacoustic instabilities in annular combustors have been observed experimentally and numerically for which this assumption does not hold. 28,29 The situation becomes more complex when the annular chamber is coupled to an annular plenum ( Fig. 3).…”

Section: B the Specific Case Of Azimuthal Modesmentioning

confidence: 99%

Progress in analytical methods to predict and control azimuthal combustion instability modes in annular chambers

2016

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Longitudinal low-frequency thermoacoustic unstable modes in combustion chambers have been intensively studied experimentally, numerically, and theoretically, leading to significant progress in both understanding and controlling these acoustic modes. However, modern annular gas turbines may also exhibit azimuthal modes, which are much less studied and feature specific mode structures and dynamic behaviors, leading to more complex situations. Moreover, dealing with 10-20 burners mounted in the same chamber limits the use of high fidelity simulations or annular experiments to investigate these modes because of their complexity and costs. Consequently, for such circumferential acoustic modes, theoretical tools have been developed to uncover underlying phenomena controlling their stability, nature, and dynamics. This review presents recent progress in this field. First, Galerkin and network models are described with their pros and cons in both the temporal and frequency framework. Then, key features of such acoustic modes are unveiled, focusing on their specificities such as symmetry breaking, non-linear modal coupling, forcing by turbulence. Finally, recent works on uncertainty quantifications, guided by theoretical studies and applied to annular combustors, are presented. The objective is to provide a global view of theoretical research on azimuthal modes to highlight their complexities and potential.

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Section: B the Specific Case Of Azimuthal Modesmentioning

confidence: 99%

Progress in analytical methods to predict and control azimuthal combustion instability modes in annular chambers

2016

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“…A particularly relevant example is the recent work on high-frequency thermoacoustic instabilities in the reheat combustor of the aforementioned GT24/26 gas turbines. 15,16 In this case, a redesigned front panel of the reheat combustor featuring built-in passive acoustic dampers was required to eliminate the limits imposed on operational flexibility by the instabilities. This example highlights the need for effective countermeasures for the high-frequency regime and for accurate methods for prediction of thermoacoustic instabilities to avoid their occurrence from early on in the design process.…”

Section: Introductionmentioning

confidence: 99%

Observation of reactive shear layer modulation associated with high-frequency transverse thermoacoustic oscillations in a gas turbine reheat combustor experiment

McClure

Berger

Bertsch

et al. 2022

International Journal of Spray and Combustion Dynamics

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This paper presents the investigation of high-frequency thermoacoustic oscillations and associated flame dynamics in an experimental gas turbine reheat combustor at atmospheric pressure. Examination of dynamic pressure measurements reveals bursts of high-frequency periodic oscillations which appear randomly amidst stochastic fluctuations in the reheat combustor. Analysis of the flame dynamics during these bursts of periodic behaviour reveals that increased heat release in the reactive shear layers of the reheat flame is associated with greater thermoacoustic driving potential. This redistribution of heat release is likely due to the stochastic nature of auto-ignition kernel formation. To determine the underlying flame-acoustic coupling mechanism behind the driving potential, phase-resolved flame dynamics over the acoustic cycle are investigated which reveal the presence of an oscillatory heat release pattern associated with the first transverse eigenmode. An in-phase interaction between the acoustic field and these heat release oscillations in the shear layer regions indicates that this phenomenon likely constitutes a thermoacoustic driving mechanism. This is an important step towards the development of models for high-frequency thermoacoustic driving mechanisms relevant to reheat combustion systems, which will allow accurate prediction and mitigation of thermoacoustic instabilities in future designs.

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