Effect of multiperforated plates on the acoustic modes in combustors

Gullaud, Elsa; Mendez, Simon; Sensiau, Claude; Nicoud, Franck; Poinsot, Thiérry

doi:10.1016/j.crme.2009.06.020

Cited by 14 publications

(15 citation statements)

References 10 publications

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“…If this fluctuating heat release and the acoustic waves are in phase, a positive feedback will occur as shown by Rayleigh (1878), Dowling (1997) and Dowling & Stow (2003). This may lead to thermoacoustic instabilities if the energy gain exceeds the losses through the boundaries and other dissipation mechanisms (Gullaud et al 2009). The instability mechanism depends strongly on the boundary conditions of the combustion chamber: the phase of the reflection coefficient will influence the resonance frequency at which the instability occurs, and the modulus will control the rate at which the energy of the instability is lost through the boundaries, determining whether the mode is stable or unstable (Williams 1985;Candel & Poinsot 1988;Culick 1988;Dowling 1995).…”

Section: Introductionmentioning

confidence: 99%

Solution of the quasi-one-dimensional linearized Euler equations using flow invariants and the Magnus expansion

2013

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The acoustic and entropy transfer functions of quasi-one-dimensional nozzles are studied analytically for both subsonic and choked flows with and without shock waves. The present analytical study extends both the compact nozzle solution obtained by Marble & Candel (1977) and the effective nozzle length proposed by Stow et al. (2002) and by Goh & Morgans (2011a) to non-zero frequencies for both modulus and phase through an asymptotic expansion of the linearized Euler equations. It also extends the piecewiselinear approximation of the velocity profile in the nozzle proposed by Moase et al. (2007) to any arbitrary profile or equivalently any nozzle geometry. The equations are written as a function of three variables, namely the dimensionless mass, total temperature and entropy fluctuations, yielding a first order linear system of differential equations with varying coefficients, which is solved using the Magnus expansion. The solution shows that both the modulus and the phase of the transfer functions of the nozzle have a strong dependence on the frequency. This holds for both choked flows and subsonic converging diverging nozzles. The method is used to compare two different nozzle geometries with the same inlet and outlet Mach numbers showing that, even if the compact solution predicts no differences between the transfer functions of the two nozzles, significant differences are found at non-zero frequencies. A parametric study is finally performed to calculate the indirect to direct noise ratio for a model combustor, showing that this ratio decreases at higher frequencies.

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Section: Introductionmentioning

confidence: 99%

Solution of the quasi-one-dimensional linearized Euler equations using flow invariants and the Magnus expansion

2013

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“…Therefore, the acoustic behavior of the perforated plates is modeled with a modified Howe model which is discussed in detail in Refs. [33,34]. Since the Strouhal numbers of the discussed unstable modes are relatively small (St < 0.5), the application of the Howe model is still justified, although the influence of interaction effect of the orifices (which is not accounted for in the Howe model) can significantly alter the acoustic impedances of perforated plates with porosities around 10% [35].…”

Section: Mesh and Boundary Conditionsmentioning

confidence: 99%

Influence of Heat Transfer and Material Temperature on Combustion Instabilities in a Swirl Burner

Kraus

Selle

Poinsot

et al. 2016

Journal of Engineering for Gas Turbines and Power

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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. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 17948 The current work focuses on the large eddy simulation (LES) of combustion instability in a laboratory-scale swirl burner. Air and fuel are injected at ambient conditions. Heat conduction from the combustion chamber to the plenums results in a preheating of the air and fuel flows above ambient conditions. The paper compares two computations: In the first computation, the temperature of the injected reactants is 300 K (equivalent to the experiment) and the combustor walls are treated as adiabatic. The frequency of the unstable mode (% 635 Hz) deviates significantly from the measured frequency (% 750 Hz).In the second computation, the preheating effect observed in the experiment and the heat losses at the combustion chamber walls are taken into account. The frequency (% 725 Hz) of the unstable mode agrees well with the experiment. These results illustrate the importance of accounting for heat transfer/losses when applying LES for the prediction of combustion instabilities. Uncertainties caused by unsuitable modeling strategies when using computational fluid dynamics for the prediction of combustion instabilities can lead to an improper design of passive control methods (such as Helmholtz resonators) as these are often only effective in a limited frequency range.

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“…This model was implemented in the ASVP code, validated against an analytical solution in the case of a simplified annular geometry and then used to compute the eigenmodes of a full helicopter chamber [33,35]. In the present work, the presence of small conical flames anchored on the perforated plate prevent the flow from generating vortices [16].…”

Section: Boundary Condition Treatment In Avspmentioning

confidence: 99%

“…In [27,29,33], the Rayleigh conductivity K a was linked to the perforated plate characteristics using the model derived by Howe [34]. This model was implemented in the ASVP code, validated against an analytical solution in the case of a simplified annular geometry and then used to compute the eigenmodes of a full helicopter chamber [33,35].…”

Section: Boundary Condition Treatment In Avspmentioning

confidence: 99%

Prediction of the Nonlinear Dynamics of a Multiple Flame Combustor by Coupling the Describing Function Methodology With a Helmholtz Solver

Cuquel

Silva

Nicoud

et al. 2013

Volume 1B: Combustion, Fuels and Emissions

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This study focuses on the numerical determination of thermo-acoustic instabilities using a combination of the Flame Describing Function (FDF) methodology and a numerical code solving the Helmholtz equation. In this framework, the FDF is defined by a set of Flame Transfer Functions (FTF) that depend on both the frequency and amplitude of acoustic perturbations. The FDF methodology has been recently used in combination with acoustic network methods to examine the nonlinear stability of generic configurations with simplified geometries. Its extension to complex 3D geometries requires the use of numerical tools such as a Helmholtz solver. In the present work, that combination is validated on a multiple injection combustor. The implementation of the FDF methodology in the Helmholtz solver is detailed before examining numerical predictions obtained by the use of an experimentally determined FDF in the Helmholtz solver. The instability frequencies and growth rates are determined for each perturbation level and different nonlinear behaviors are exhibited depending on the combustor geometry. The case of linearly unstable modes reaching limit cycles is first examined. A more complex case involving mode switching is then examined when two unstable modes are present. In this situation, the most unstable mode in the linear regime triggers another * Address all correspondence to this author: alexis.cuquel@ecp.fr unstable mode at a higher perturbation level. These numerical calculations are compared with experimental data and exhibit a good match in terms of amplitude and frequency reached by the limit cycle.

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Effect of multiperforated plates on the acoustic modes in combustors

Cited by 14 publications

References 10 publications

Solution of the quasi-one-dimensional linearized Euler equations using flow invariants and the Magnus expansion

Solution of the quasi-one-dimensional linearized Euler equations using flow invariants and the Magnus expansion

Influence of Heat Transfer and Material Temperature on Combustion Instabilities in a Swirl Burner

Prediction of the Nonlinear Dynamics of a Multiple Flame Combustor by Coupling the Describing Function Methodology With a Helmholtz Solver

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