The Spectral Shape of Combustion Noise

Tam, Christopher K. W.

doi:10.1260/1475-472x.14.3-4.431

Cited by 9 publications

(6 citation statements)

References 34 publications

(61 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a recent study, Tam [2015] used an empirical approach and proposed that combustion noise spectrum is similar to the noise spectrum from large turbulence structures of high-speed jets. Good agreement was found by comparing the proposed similarity spectrum and a large set of combustion noise spectra.…”

Section: Experimental Studies Of Sound Generation By Premixed Flamesmentioning

confidence: 99%

Sound generation by turbulent premixed flames

et al. 2018

View full text Add to dashboard Cite

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.

show abstract

Section: Experimental Studies Of Sound Generation By Premixed Flamesmentioning

confidence: 99%

Sound generation by turbulent premixed flames

et al. 2018

View full text Add to dashboard Cite

show abstract

“…[14][15][16] Another source of indirect combustion noise due to compositional inhomogeneities which cause the transfer of chemical potential energy into acoustic energy in the accelerating flow has recently been identified in literature. [17][18][19] The spectral shape of direct combustion noise from open flames has frequently been studied, e.g., experimentally in Kotake and Takamoto 20 and Rajaram and Lieuwen 21 at varying fuels, flow parameters, and burner geometries, numerically in Schlimpert et al, 22 and empirically in Tam et al 23 Tam et al 23 analyzed experimental data from the literature and derived an empirical law for the heat release spectrum. Schlimpert et al 22 studied the heat release spectra and the acoustic response to heat release fluctuations in a low, medium, and high frequency range.…”

Section: Introductionmentioning

confidence: 99%

“…17–19 The spectral shape of direct combustion noise from open flames has frequently been studied, e.g., experimentally in Kotake and Takamoto 20 and Rajaram and Lieuwen 21 at varying fuels, flow parameters, and burner geometries, numerically in Schlimpert et al., 22 and empirically in Tam et al. 23 Tam et al. 23 analyzed experimental data from the literature and derived an empirical law for the heat release spectrum.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Impact of burner plenum acoustics on the sound emission of a turbulent lean premixed open flame

Herff

Pausch

Nawroth

et al. 2020

International Journal of Spray and Combustion Dynamics

View full text Add to dashboard Cite

The acoustic field of a turbulent lean cpremixed open flame is numerically investigated by a hybrid method solving the Navier-Stokes equations in a large-eddy simulation formulation and the acoustic perturbation equations. The interaction of acoustic modes of a burner plenum and the turbulent flame is analyzed with respect to the sound emission of the flame. It is investigated if a simplified computation yields a good broadband agreement of the sound pressure spectrum with experimental measurements. The results of two numerical setups, i.e., the first configuration consists of the burner plus the plenum geometry while in the second configuration the plenum is neglected, which is often done in technical applications due to computational efficiency reasons, are compared with experimental findings. It can be concluded that the plenum has a pronounced impact on the dynamics and combustion noise of the open flame. To be more precise, the comparative juxtaposition of the numerical and experimental results shows a good agreement only for the full burner-plenum computation since the interaction of the acoustic quarter-wave modes of the burner plenum with the jet flow has to be captured. The interaction of these quarter-wave modes with the flow is analyzed and the acoustic response to heat release fluctuations of the flame of the full burner-plenum computation is compared to that of the simplified burner computation, in which the plenum acoustics is neglected. Due to the excitation by the plenum acoustics, the jet flow of the full burner plenum contains higher turbulent kinetic energy and the flame is excited at several additional frequencies which result in distinct peaks in the acoustic spectrum and a higher overall sound pressure level.

show abstract

“…Several experimental studies of open, turbulent, premixed and diffusion flames have demonstrated the broadband nature of combustion noise [3][4][5][6] for a large variety of geometries and flow variables. A recent study by Tam [7] compared experimental hydrocarbon combustion noise spectra from turbulent open flames, low Mach number jets, can-type combustors, auxiliary power units and turbofan engines. This study verified that combustion noise broadband spectrum can be satisfactory modeled by the similarity spectrum of the noise from large turbulent structures in high speed jets.…”

mentioning

confidence: 99%

Role of Coherent Structures in Turbulent Premixed Flame Acoustics

Brouzet¹,

Haghiri²,

Talei³

et al. 2020

AIAA Journal

View full text Add to dashboard Cite

Spectral proper orthogonal decomposition (SPOD) is applied to direct numerical simulation (DNS) datasets of a lean and a stoichiometric methane/air turbulent premixed jet flame. SPOD is used to extract the coherent structures that correlate with the radiated sound by using an inner product based on a linearized disturbance energy. Two types of structures are prominent in the data. The first type arises in the jet's shear layer and is linked to the Kelvin-Helmholtz (K-H) instability, which is an important mechanism of sound generation in non-reacting jets. These structures produce sound through deformation of the flame front in the shear layer. They contain most of the acoustic energy and are dominant at Strouhal numbers (defined based on the jet's diameter and the inlet mean velocity) less than unity. The second type of structures is found near the jet centreline, where large fluctuations of the flame surface are observed. The structures are linked to small non-linear flame dynamics and to the Orr mechanism. They travel at a speed close to the inlet mean velocity and are important at higher Strouhal numbers. Regardless of their energy content, both types of structures have important contributions to the broadband nature of combustion noise.

show abstract

The Spectral Shape of Combustion Noise

Cited by 9 publications

References 34 publications

Sound generation by turbulent premixed flames

Sound generation by turbulent premixed flames

Impact of burner plenum acoustics on the sound emission of a turbulent lean premixed open flame

Role of Coherent Structures in Turbulent Premixed Flame Acoustics

Contact Info

Product

Resources

About