Theory of combustion noise

Chiu, H. H.; Summerfield, M.

doi:10.1016/0094-5765(74)90063-0

Cited by 91 publications

(59 citation statements)

References 7 publications

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“…At low frequencies, the acoustic waves that propagate in a constant area duct will be plane and one-dimensional. 29,31 Assuming plane wave flow perturbations and non-diffusive flow throughout, equation (4) simplifies to the expression derived by Dowling et al, 32 " Ds…”

Section: Generation Of Entropy Waves At the Flamementioning

confidence: 99%

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Entropy noise: A review of theory, progress and challenges

Morgans

Durán

2016

International Journal of Spray and Combustion Dynamics

119

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Combustion noise comprises two components: direct combustion noise and indirect combustion noise. The latter is the lesser studied, with entropy noise believed to be its main component. Entropy noise is generated via a sequence involving diverse flow physics. It has enjoyed a resurgence of interest over recent years, because of its increasing importance to aero-engine exhaust noise and a recognition that it can affect gas turbine combustion instabilities. Entropy noise occurs when unsteady heat release rate generates temperature fluctuations (entropy waves), and these subsequently undergo acceleration. Five stages of flow physics have been identified as being important, these being (a) generation of entropy waves by unsteady heat release rate; (b) advection of entropy waves through the combustor; (c) acceleration of entropy waves through either a nozzle or blade row, to generate entropy noise; (d) passage of entropy noise through a succession of turbine blade rows to appear at the turbine exit; and (e) reflection of entropy noise back into the combustor, where it may further perturb the flame, influencing the combustor thermoacoustics. This article reviews the underlying theory, recent progress and outstanding challenges pertaining to each of these stages.

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Section: Generation Of Entropy Waves At the Flamementioning

confidence: 99%

“…This acts as an acoustic ''monopole'' source, [1][2][3][4][5][6] generating acoustic waves known as ''direct combustion noise.'' Unsteady heat release rate also generates temperature variations, known as ''hot spots'' or entropy waves, which may eventually go on to generate entropy noise.…”

Section: Introductionmentioning

confidence: 99%

Entropy noise: A review of theory, progress and challenges

Morgans

Durán

2016

International Journal of Spray and Combustion Dynamics

119

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“…A number of theoretical investigations is reported in the literature: Ref. 21 sets forth several possible combustion noise source terms to be evaluated; Ref. 22 gives a correlation of data, based on theory, for the acoustic power in a combustor with engine operating parameters; Ref.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the effect on combustor noise measurements of acoustic waves reflected by the turbine and combustor inlet

Huff

1984

9th Aeroacoustics Conference

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Spectral analyses of static pressure fluctuations measured in turbine engine combustors at low engine speed show good agreement with theory. At idle speed the high pressure turbine is unchoked. Above idle speed the turbine chokes and a significant change in the shape of the measured combustor pressure spectrum is observed. A simplified theoretical model of the acoustic pressure generated in the combustor due' to the turbulence-flame front interaction did not account for acoustic waves reflected from the turbine. By retaining this simplified combustion noise source model and adding a partial reflecting plane at the turbine and combustor inlet, a simple theoretical model has been developed that reproduces the undulations in the combustor fluctuating pressure spectra. Plots of the theoretical combustor fluctuating pressure spectra are compared to the measured pressure spectra obtained from the CF6-50 turbofan engine over a range of engine operating speeds. Reasonable agreement exists, and it is thus concluded that the simplified combustion noise theory when modified by a simple turbine reflecting plane adequately accounts for the changes in measured combustor pressure spectra. It is further concluded that the shape of the pressure spectra downstream of the turbine, neglecting noise generated by the turbine itself, will be the combustion noise spectra essentially unchanged except for the level reduction due to the energy blocked by the turbine.

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“…La primera se basa en la ecuación de Ligthhill [33] y la segunda en la ecuación de Phillips [60,77]. Sin embargo, la teoría que se va a describir de forma simplificada a continuación es la de Strahle [180], ya que es una combinación de las dos anteriores.…”

Section: Modelo De Analogía Acústicaunclassified

“…Por otra parte la aportación de Chiu et al [33] está basada en la construcción de la ecuación de Phillips mediante el uso de la variable η = ln p en el cálculo de la derivada temporal total de la ecuación 2.12. Restándole la divergencia de la ecuación 2.7, se obtendría:…”

Section: Modelo De Analogía Acústicaunclassified

Estudio CFD de la resonancia en la cámara de combustión de Motores Diesel HDI

Ramírez¹,

José²

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Theory of combustion noise

Cited by 91 publications

References 7 publications

Entropy noise: A review of theory, progress and challenges

Entropy noise: A review of theory, progress and challenges

Analysis of the effect on combustor noise measurements of acoustic waves reflected by the turbine and combustor inlet

Estudio CFD de la resonancia en la cámara de combustión de Motores Diesel HDI

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