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Nonlinear analytical flame models with amplitude-dependent time-lag distributions

Heckl

Nonlinear analytical flame models with amplitude-dependent time-lag distributions Thumbnail


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Abstract

In the present work, we formulate a new method to represent a given Flame Describing Function by analytical expressions. The underlying idea is motivated by the observation that different types of perturbations in a burner travel with different speeds and that the arrival of a perturbation at the flame is spread out over time. We develop an analytical model for the Flame Describing Function, which consists of a superposition of several Gaussians, each characterised by three amplitude-dependent quantities: central time-lag, peak value and standard deviation. These quantities are treated as fitting parameters, and they are deduced from the original Flame Describing Function by using error minimisation and nonlinear optimisation techniques. The amplitude-dependence of the fitting parameters is also represented analytically (by linear or quadratic functions). We test our method by using it to make stability predictions for a burner with well-documented stability behaviour (Noiray's matrix burner). This is done in the time-domain with a tailored Green's function approach.

Acceptance Date Jul 30, 2017
Publication Date Dec 1, 2018
Publicly Available Date Mar 28, 2024
Journal International Journal of Spray and Combustion Dynamics
Print ISSN 1756-8277
Publisher SAGE Publications
Pages 264-276
DOI https://doi.org/10.1177/1756827717728056
Keywords flame transfer function, amplitude-dependence, multiple time-lags, Green's function, stability analysis
Publisher URL http://journals.sagepub.com/doi/full/10.1177/1756827717728056

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