# Non-normality in combustion–acoustic interaction in diffusion flames: a critical revision

@article{Magri2013NonnormalityIC, title={Non-normality in combustion–acoustic interaction in diffusion flames: a critical revision}, author={Luca Magri and Koushik Balasubramanian and R. I. Sujith and Matthew P. Juniper}, journal={Journal of Fluid Mechanics}, year={2013}, volume={733}, pages={681 - 683} }

Abstract Perturbations in a non-normal system can grow transiently even if the system is linearly stable. If this transient growth is sufficiently large, it can trigger self-sustained oscillations from small initial disturbances. This has important practical consequences for combustion–acoustic oscillations, which are a persistent problem in rocket and aircraft engines. Balasubramanian & Sujith (J. Fluid Mech., vol. 594, 2008, pp. 29–57) modelled an infinite-rate chemistry diffusion flame in an…

## 18 Citations

Non-normality and nonlinearity in combustion–acoustic interaction in diffusion flames – CORRIGENDUM

- EngineeringJournal of Fluid Mechanics
- 2013

Recent investigations by L. Magri and M. P. Juniper have brought to light certain errors in the paper by Balasubramanian and Sujith (Journal of Fluid Mechanics, vol. 594, 2008, pp. 29–57). The…

Global modes, receptivity, and sensitivity analysis of diffusion flames coupled with duct acoustics

- PhysicsJournal of Fluid Mechanics
- 2014

Abstract In this theoretical and numerical paper, we derive the adjoint equations for a thermo-acoustic system consisting of an infinite-rate chemistry diffusion flame coupled with duct acoustics. We…

Effect of entropy waves on transient energy growth of flow disturbances in triggering thermoacoustic instability

- Physics, Engineering
- 2016

A systems perspective on non-normality in low-order thermoacoustic models: Full norms, semi-norms and transient growth

- Physics
- 2017

Non-normal transient growth of energy is a feature encountered in many physical systems. Its observation is intimately related to the norm used to describe the system dynamics. For a multi-physics…

Adjoint Methods as Design Tools in Thermoacoustics

- PhysicsApplied Mechanics Reviews
- 2019

In a thermoacoustic system, such as a flame in a combustor, heat release oscillations couple with acoustic pressure oscillations. If the heat release is sufficiently in phase with the pressure, these…

A Theoretical Approach for Passive Control of Thermoacoustic Oscillations: Application to Ducted Flames

- Engineering, Physics
- 2013

In this paper, we develop a linear technique that predicts how the stability of a thermoacoustic system changes due to the action of a generic passive feedback device or a generic change in the base…

Minimal energy thresholds for triggering in the Rijke tube: the effect of the time delay

- PhysicsJournal of Fluid Mechanics
- 2022

Abstract Triggering is the process by which a linearly stable thermoacoustic system can reach self-sustained oscillations. This nonlinear phenomenon is activated only for sufficiently large…

Effect of axial diffusion on the response of diffusion flames to axial flow perturbations

- Engineering
- 2016

Thermoacoustic Instabilities in Counterflow Diffusion Flames

- Physics, Engineering
- 2019

Thermoacoustic instabilities arise in combustion systems from a coupling between the unsteady heat release of the flame and the underlying acoustic field. Although thermoacoustics have been studied…

Forced response of laminar non-premixed jet flames

- Engineering, PhysicsProgress in Energy and Combustion Science
- 2019

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The role of non-normality and nonlinearity in flame–acoustic interaction in a ducted diffusion flame is investigated in this paper. The infinite rate chemistry model is employed to study unsteady…

Non-normality and nonlinearity in combustion–acoustic interaction in diffusion flames – CORRIGENDUM

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Recent investigations by L. Magri and M. P. Juniper have brought to light certain errors in the paper by Balasubramanian and Sujith (Journal of Fluid Mechanics, vol. 594, 2008, pp. 29–57). The…

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The five sections of these notes will one day be the first five chapters of a book, to appear some time after 2001.