Acoustic radiation from weakly wrinkled premixed flames

Lieuwen, Tim; Mohan, S.; Rajaram, Rajesh; Preetham,

doi:10.1016/j.combustflame.2005.08.004

Cited by 17 publications

(11 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…More recently, Ihme et al [4] successfully computed the sound emitted from a turbulent diffusion flame by combining a large eddy simulation and a computational aeroacoustic method, providing precious information about the combustion-generated noise. The experimental and theoretical work of Candel et al [5,6] about the noise generated by unsteady laminar flames, as well as the developments of Crighton et al [7] and the experimental investigations of Rajaram and Lieuwen [8,9] and Lieuwen et al [10] about combustion-generated noise of turbulent flames, are also an important source of information for direct noise comprehension. However, several studies performed in this field concern the flame acoustic radiation toward the free far field, and in the case of confined systems like aeroengines, another source of noise appears to be relevant: the entropy noise.…”

Section: Leykomentioning

confidence: 98%

Comparison of Direct and Indirect Combustion Noise Mechanisms in a Model Combustor

Leyko¹,

2009

View full text Add to dashboard Cite

Core noise in aeroengines is due to two main mechanisms: direct combustion noise, which is generated by the unsteady expansion of burning gases, and indirect combustion noise, which is due to the acceleration of entropy waves (temperature fluctuations generated by unsteady combustion) within the turbine stages. This paper shows how a simple burner model (a flame in a combustion chamber terminated by a nozzle) can be used to scale direct and indirect noise. An analytical formulation is used for waves generated by combustion. The transmission and generation of waves through the nozzle is calculated using both the analytical results of Marble and Candel (Marble, F. E., and Candel, S., "Acoustic Disturbances from Gas Nonuniformities Convected Through a Nozzle," Journal of Sound and Vibration, Vol. 55, 1977, pp. 225-243.) and a numerical tool. Numerical results for the nozzle verify and extend the analytical approach. The analytical relations for the combustion and the nozzle provide simple scaling laws for direct and indirect noise ratio as a function of the Mach number in the combustion chamber and at the nozzle outlet. Nomenclature A = nozzle cross-sectional area, m 2 A c = throat nozzle cross-sectional area, m 2 A f = combustor cross-sectional area, m 2 c = speed of sound, m=s c p = massic heat capacity at constant pressure, J=K=kg c v = massic heat capacity at constant volume, J=K=kg ' f = flame length, m ' n = nozzle length, m M = Mach number _ m = mass flow rate, kg=s PWfg = spectral power density of computed with Welch's method p = thermodynamic pressure, Pa _ Q = heat release rate, W _ q = heat release rate per volume unit, W=m 3 r = massic ideal gas constant, J=K=kg s = massic entropy, J=K=kg T = temperature, K t = time, s u = gas velocity, m=s w S = dimensionless entropy wave w = dimensionless acoustic wave propagating downstream w= dimensionless acoustic wave propagating upstream x = x-axis value, m y = y-axis value, m z = z-axis value, m = specific heat capacities ratio = Dirac distribution = ratio between indirect and direct noise = mass density, kg=m 3 = temporal mean value of 0 = temporal fluctuation value of = reduced angular pulsation ! = angular pulsation, rad=s Subscripts AA = acoustic response of the nozzle to an acoustic perturbation CC = response of the combustion chamber to a heat release fluctuation SA = acoustic response of the nozzle to an entropy perturbation t = total quantity of 0 = quantity upstream from the combustor 1 = quantity downstream from the combustor and upstream from the nozzle 2 = quantity downstream from the nozzle

show abstract

Section: Leykomentioning

confidence: 98%

Comparison of Direct and Indirect Combustion Noise Mechanisms in a Model Combustor

Leyko¹,

2009

View full text Add to dashboard Cite

show abstract

“…Several later works have since also based their arguments on extensions of Lighthill's and other acoustic analogies (e.g. Hassan 1974;Kotake 1975;Strahle 1978;Dowling 1992;Lieuwen, Mohan & Rajaram 2006). Under the assumptions of low Mach number and a constant average mixture molecular weight, Lighthill's acoustic analogy can be simplified to an inhomogeneous wave equation with a single monopolar source term (Strahle 1978;Dowling 1992;Truffaut, Searby & Boyer 1998).…”

Section: Introductionmentioning

confidence: 97%

Sound generation by laminar premixed flame annihilation

2011

View full text Add to dashboard Cite

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.

show abstract

“…Hassan (3), and nowadays for example experimentally by Lieuwen et al (4) and numerically by Ihme et al (5). According to the numerous studies in this field, the so-called direct noise is mainly caused by the unsteady heat release rate.…”

Section: Introductionmentioning

confidence: 99%

Numerical and analytical modelling of entropy noise in a supersonic nozzle with a shock

Leyko

Moreau

Nicoud

et al. 2011

Journal of Sound and Vibration

View full text Add to dashboard Cite

. Numerical and analytical modelling of entropy noise in a supersonic nozzle with a shock. Journal of Sound and Vibration, Elsevier, 2011, 330 (16) that the acoustic impedance downstream of the nozzle must be accounted for to properly recover the experimental pressure signal. The analytical method can also be used to optimize the experimental parameters and avoid the interaction between transmitted and reflected waves.

show abstract

Acoustic radiation from weakly wrinkled premixed flames

Cited by 17 publications

References 19 publications

Comparison of Direct and Indirect Combustion Noise Mechanisms in a Model Combustor

Comparison of Direct and Indirect Combustion Noise Mechanisms in a Model Combustor

Sound generation by laminar premixed flame annihilation

Numerical and analytical modelling of entropy noise in a supersonic nozzle with a shock

Contact Info

Product

Resources

About