Two-time correlation of heat release rate and spectrum of combustion noise from turbulent premixed flames

Liu, Yu

doi:10.1016/j.jsv.2015.05.027

Cited by 9 publications

(6 citation statements)

References 38 publications

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“…In one of the earlier studies of combustion noise, Smith & Kilham [1963] showed that the emitted sound by open turbulent premixed flames can be modelled by a distribution of monopolar sources throughout the flame. Changes in the flame volume or equivalently the heat release rate fluctuations have also been demonstrated to be the primary source of sound in other studies of turbulent flames (e.g., Hurle et al [1968]; Strahle [1978] Liu [2015]). However, there is relatively little known about the phenomena that produce large fluctuations of the heat release rate and therefore generated sound.…”

Section: Discussionmentioning

confidence: 95%

“…Many of the subsequent theoretical studies of sound generation by turbulent premixed flames have also attempted to relate the radiated sound to changes in the flame volume or the heat release rate. Indeed, heat release rate fluctuations have been demonstrated to be significant in many studies of sound generation by premixed flames e.g., Candel et al [2004]; Dowling [1992]; Hurle et al [1968]; Kotake & Takamoto [1990]; Liu [2015]; Rajaram & Lieuwen [2009]; Schuller et al [2003]; Strahle [1978]; Swaminathan et al [2011a,b]. Based on his model, Bragg [1963] also pointed out that the noise emission will be intensified by increasing the reactivity of the fuel and the flow velocity in the system.…”

Section: Fundamentals Of Combustion Noisementioning

confidence: 99%

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Sound generation by turbulent premixed flames

et al. 2018

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This paper presents a numerical study of the sound generated by turbulent, premixed flames. Direct numerical simulations (DNS) of two round jet flames with equivalence ratios of 0.7 and 1.0 are first carried out. Single-step chemistry is employed to reduce the computational cost, and care is taken to resolve both the near and far fields and to avoid noise reflections at the outflow boundaries. Several significant features of these two flames are noted. These include the monopolar nature of the sound from both flames, the stoichiometric flame being significantly louder than the lean flame, the observed frequency of peak acoustic spectral amplitude being consistent with prior experimental studies and the importance of so-called ‘flame annihilation’ events as acoustic sources. A simple model that relates these observed annihilation events to the far-field sound is then proposed, demonstrating a surprisingly high degree of correlation with the far-field sound from the DNS. This model is consistent with earlier works that view a premixed turbulent flame as a distribution of acoustic sources, and provides a physical explanation for the well-known monopolar content of the sound radiated by premixed turbulent flames.

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Section: Discussionmentioning

confidence: 95%

Section: Fundamentals Of Combustion Noisementioning

confidence: 99%

Sound generation by turbulent premixed flames

et al. 2018

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“…There are many studies on the nature of turbulence and turbulent flows with combustion that involve sound generation (for examples see Bray [6], Roberts and Leventhall [7], Clavin and Siggia [8], Kilham and Kirmani [9], Bailly et al [10], or Smith and Kilham [11]). Swaminathan et al [12], Liu [13], and Liu et al [14] examined heat release, correlations, and sound radiation from turbulent premixed flames. Swirling flame studies of Wasle [15] and Winkler et al [16] examined the heat release and acoustic efficiency of premixed flames.…”

Section: Introductionmentioning

confidence: 99%

Analytical Equations for Thermoacoustic Instability Sources and Acoustic Radiation from Reacting Turbulence

Miller

2020

International Journal of Aerospace Engineering

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We seek to ascertain and understand source terms that drive thermoacoustic instability and acoustic radiation. We present a new theory based on the decomposition of the Navier-Stokes equations coupled with the mass fraction equations. A series of solutions are presented via the method of the vector Green’s function. We identify both combustion-combustion and combustion-aerodynamic interaction source terms. Both classical combustion noise theory and classical Rayleigh criterion are recovered from the presently developed more general theory. An analytical spectral prediction method is presented, and the two-point source terms are consistent with Lord Rayleigh’s instability model. Particular correlations correspond to the source terms of Lighthill, which represent the noise from turbulence and additional terms for the noise from reacting flow.

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“…A combustion noise source vector in terms of emitted characteristic wave amplitudes may be extracted experimentally [4,11] , but the experimental assessment of the combustion noise source is difficult and laborious. An alternative approach relies on a Strouhal number scaling for the noise source [12][13][14] . These models predict an increase of the combustion noise source strength towards a peak frequency, with a subsequent roll-off to higher frequencies.…”

Section: Introductionmentioning

confidence: 99%