Constructive and Destructive Interference of Acoustic and Entropy Waves in a Premixed Combustor with a Choked Exit

Polifke, Wolfgang; Paschereit, Christian Oliver; Paschereit, Klaus

doi:10.20855/ijav.2001.6.382

Cited by 91 publications

(91 citation statements)

References 15 publications

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“…More recent works (e.g., [4]) show that interference between entropy waves and pressure disturbances can be constructive or destructive, which can further aggravate the problem. Several mechanisms contribute to the occurrence of thermoacoustic instabilities [11]: fluctuations in the air/fuel ratio, acoustic-convective waves and entropy waves.…”

Section: Experimental Diagnosismentioning

confidence: 99%

“…Polifke et al (2001) point out that the feedback between the combustion chamber acoustics and the entropy waves would be important, especially for lower modes and even at higher frequencies than those normally associated with convection waves [4]. The relative phase between the acoustic signal at the combustion chamber outlet and the pressure pulse generated by the entropy wave determines whether the combustion chamber's susceptibility to thermoacoustic oscillations is improved or reduced by the interaction between the entropy waves and the acoustics of the combustion chamber.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Measuring Sound Pressure Levels during Thermoacoustic Instabilities in Large Engines: Case Study

González¹,

Ottieri²,

Kovar³

et al. 2017

JMP

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This paper attempts to present some registers of sound pressure levels during the operation of large diesel engines (10 MW). During these registers we have found the preparation, occurrence and ending of events of thermoacoustic instability. They appear after a loosing of chaos period or a reduction in fluctuations in some frequencies. The most interesting phenomena were registered at low frequencies. However, they were accompanied by variations in sound emissions at medium and high frequencies. As there has been very little published data concerning these phenomena at real scale, it is imperative to point out that every quasi-stationary state we have measured during these episodes has lasted some minutes, significantly much more time than that of lab scale results.

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Section: Experimental Diagnosismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measuring Sound Pressure Levels during Thermoacoustic Instabilities in Large Engines: Case Study

González¹,

Ottieri²,

Kovar³

et al. 2017

JMP

View full text Add to dashboard Cite

show abstract

“…As explained by Hield et al [43], the behaviour of such an instability depends to the first order on the geometry. The spatial dispersion of entropy fluctuations by the combustor aerodynamics [45] and the constructive/destructive phase dependency [26] play an important role on the establishment of a coupling between acoustic and entropy modes.…”

Section: Accounting For Entropy Convection In a Zero Mach Mean Flowmentioning

confidence: 99%

“…Acoustic waves transmitted through the distributor produce indirect combustion noise, while acoustic waves travelling back to the flame may trigger low-frequency resonant modes called rumble [26,27]. This important mechanism for combustion instabilities is not accounted for in a Helmholtz solver, since entropy fluctuations do not propagate if the mean flow is at rest.…”

Section: Introductionmentioning

confidence: 99%

Accounting for convective effects in zero-Mach-number thermoacoustic models

Motheau

Selle

Nicoud

2014

Journal of Sound and Vibration

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a b s t r a c tThis paper presents a methodology to account for some mean-flow effects on thermoacoustic instabilities when using the zero-Mach-number assumption. It is shown that when a computational domain is represented under the M¼ 0 assumption, a nonzero-Machnumber element can simply be taken into account by imposing a proper acoustic impedance at the boundaries so as to mimic the mean flow effects in the outer, not computed flow domain. A model that accounts for the coupling between acoustic and entropy waves is presented. It relies on a "delayed entropy coupled boundary condition" (DECBC) for the Helmholtz equation satisfied by the acoustic pressure. The model proves able to capture low-frequency entropic modes even without mean-flow terms in the fluctuating-pressure equation.

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“…, N s ) and unity Lewis number (Le = λ/(γ c p ) = 1, where c p = ∑ Ns α=1 c pα Y α ). Therefore, the term V in Equation (14) reduces to diffusion of entropy:…”

Section: Theoretical Foundationmentioning

confidence: 99%

Entropy Transport Equation in Large Eddy Simulation for Exergy Analysis of Turbulent Combustion Systems

Qariq

Sheikhi

Janbozorgi

et al. 2010

Entropy

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The transport equation of entropy is introduced in large eddy simulation to perform exergy analysis of turbulent combustion systems. The sources of exergy destruction can be evaluated by analyzing entropy generation terms, which appear in unclosed forms in this equation. The closure is based on the filtered density function (FDF) methodology. The primary advantage of FDF is that chemical reaction and its entropy generation effects appear in closed forms. This methodology involves a stochastic model, which is being developed to account for the subgrid scale transport of entropy.

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Constructive and Destructive Interference of Acoustic and Entropy Waves in a Premixed Combustor with a Choked Exit

Cited by 91 publications

References 15 publications

Measuring Sound Pressure Levels during Thermoacoustic Instabilities in Large Engines: Case Study

Measuring Sound Pressure Levels during Thermoacoustic Instabilities in Large Engines: Case Study

Accounting for convective effects in zero-Mach-number thermoacoustic models

Entropy Transport Equation in Large Eddy Simulation for Exergy Analysis of Turbulent Combustion Systems

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