Numerical analysis of the acoustic field of reacting flows via acoustic perturbation equations

Bui, T. Ph.; Schröder, Wolfgang; Meinke, Matthias

doi:10.1016/j.compfluid.2007.10.014

Cited by 54 publications

(31 citation statements)

References 35 publications

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“…Bui et al 2005;Birbaud et al 2006;Ihme, Bodony & Pitsch 2006;Flemming, Sadiki & Janicka 2007;Bui, Schröder & Meinke 2008;Ihme, Pitsch & Bodony 2009) and direct numerical simulations (DNS) (e.g. Miyauchi, Tanahashi & Li 2001;Zhao & Frankel 2001;Tanahashi et al 2002;Laverdant & Thévenin 2003Shalaby, Laverdant & Thévenin 2009;Najafi-Yazdi, Lew & Mongeau 2010).…”

Section: Introductionmentioning

confidence: 98%

Sound generation by laminar premixed flame annihilation

2011

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This paper presents a numerical and theoretical investigation of the sound generated by premixed flame annihilation. Planar, axisymmetric and spherically symmetric flame annihilation events are considered. The compressible Navier-Stokes, energy and progress variable equations are first solved using simple chemistry simulations, resolving both the flame dynamics and the acoustics. These simulations show that the amplitude of the far-field sound produced by the annihilation events depends on the flame thickness, particularly for the axisymmetric and spherically symmetric flame annihilation events. The flame propagation velocity is also always observed to increase significantly prior to flame annihilation, which is in keeping with other reported experimental and numerical studies. A theory is then presented that relates the far-field sound to the flame annihilation event by using a previously reported and extended form of Lighthill's acoustic analogy. A comparison with the numerical results shows that this theory accurately represents the far-field sound produced by considering only the temporal heat release source term in Lighthill's acoustic analogy, as reported by others. Additional assumptions of an infinitely thin flame and constant flame speed are then invoked in an attempt to simplify the problem. In the planar annihilation, this theory results in good predictions of the overall pressure change. However, these assumptions lead to significant under-prediction of the amplitude of far-field sound produced for the axisymmetric and spherically symmetric annihilation events. Finally, dimensional reasoning supported by the simulations and theory is used to develop scalings of the far-field sound in terms of the flame parameters.

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Section: Introductionmentioning

confidence: 98%

Sound generation by laminar premixed flame annihilation

2011

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“…47,48 This strategy also differs from the acoustic perturbation equation formulation that has been developed to analyze combustion noise. 49 In this hybrid approach, the noise sources are extracted from large-eddy simulations and the sound field is computed with an aeroacoustic solver, but the flame does not respond to the incident sound field. In the linear method presented herein, a steady base flame is computed and perturbations are supposed to develop around this base state without modifying it.…”

Section: Introductionmentioning

confidence: 99%

Response analysis of a laminar premixed M-flame to flow perturbations using a linearized compressible Navier-Stokes solver

Blanchard

Schuller

Sipp³

et al. 2015

Physics of Fluids

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International audienceThe response of a laminar premixed methane-air flame subjected to flow perturbations around a steady state is examined experimentally and using a linearized compressible Navier-Stokes solver with a one-step chemistry mechanism to describe combustion. The unperturbed flame takes an M-shape stabilized both by a central bluff body and by the external rim of a cylindrical nozzle. This base flow is computed by a nonlinear direct simulation of the steady reacting flow, and the flame topology is shown to qualitatively correspond to experiments conducted under comparable conditions. The flame is then subjected to acoustic disturbances produced at different locations in the numerical domain, and its response is examined using the linearized solver. This linear numerical model then allows the componentwise investigation of the effects of flow disturbances on unsteady combustion and the feedback from the flame on the unsteady flow field. It is shown that a wrinkled reaction layer produces hydrodynamic disturbances in the fresh reactant flow field that superimpose on the acoustic field. This phenomenon, observed in several experiments, is fully interpreted here. The additional perturbations convected by the mean flow stem from the feedback of the perturbed flame sheet dynamics onto the flow field by a mechanism similar to that of a perturbed vortex sheet. The different regimes where this mechanism prevails are investigated by examining the phase and group velocities of flow disturbances along an axis oriented along the main direction of the flow in the fresh reactant flow field. It is shown that this mechanism dominates the low-frequency response of the wrinkled shape taken by the flame and, in particular, that it fully determines the dynamics of the flame tip from where the bulk of noise is radiated

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“…(3) presented in Section 2 is derived here for a reacting mixture of perfect gases. This expression can be found in other references, as for examples in [28,31,32], using different approximations. The objective is to clarify the hypotheses made in this study to obtain Eq.…”

Section: Appendixmentioning

confidence: 90%

“…The following relation is exploited: (1) where ρ andq denote density and heat release rate (per unit volume) perturbations, respectively, c corresponds to the speed of sound and γ indicates the specific heat capacity ratio of gases. Similar expressions were already used in simulations of combustion noise radiated by turbulent diffusion flames [27][28][29]. It constitutes an interesting alternative to measure heat release rate fluctuations because different techniques may be envisaged to detect density fluctuations.…”

Section: Introductionmentioning

confidence: 89%

“…The terms in the brackets correspond to the thermal conductivity λ, the viscous stress tensor τ and the flow velocity v. This transport equation may be found in slightly different forms in [28,31,32] with other approximations. Body forces, such as gravity forces, can be neglected in most practical combustion chambers because the flames are submitted to large pressure gradients.…”

Section: Density Disturbances In a Reacting Flowmentioning

confidence: 99%

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