High-Speed Flow Field Measurements of Turbulent Jet Flames Undergoing Shear Layer Manipulation

Nawroth, Holger; Paschereit, Christian Oliver

doi:10.2514/6.2016-1841

Cited by 3 publications

(7 citation statements)

References 19 publications

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“…The flame is excited by turbulence leading to a broadband noise spectrum and additionally by acoustic modes which generate noise at several distinct frequencies. A good agreement between the spectra of the CAA prediction and the experimental data by Nawroth and Paschereit [35] is found in the mid frequency range. The spectral decay rate

f^{- 2.1}

is similar to the results reported by Rajaram and Lieuwen [41].…”

Section: Resultssupporting

confidence: 74%

“…The acoustic pressure is measured at a microphone position

r = 30 d

, that is, on the burner outlet plane at a distance of

1.05

m from the centerline. The experiments were done by Nawroth and Paschereit [35] in an anechoic environment.…”

Section: Numerical Configurationsmentioning

confidence: 99%

“…Schematics (not to scale) of the experimental burner configuration of the turbulent jet flame by Nawroth and Paschereit [35,38]…”

Section: Numerical Configurationsmentioning

confidence: 99%

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Analysis of the sound sources of lean premixed methane–air flames

et al. 2021

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Two investigations on the sound generation mechanisms of lean methane–air flames are reviewed and linked. A two‐step approach is used for the analysis. First, the compressible conservation equations are solved in a large‐eddy simulation formulation to compute the acoustic source terms of the reacting fluid. Second, the acoustic source terms are used in computational aeroacoustics simulations to determine the acoustic field by solving the acoustic perturbation equations. To identify the contributions of the different source terms to the overall sound emission of the flames different source term formulations are considered in the computational aeroacoustics simulations. The results of various flames of increasing complexity are shown: harmonically excited laminar flames, a turbulent jet flame, and an unconfined and a confined swirl flame. The results show that in general the heat release source alone does not determine the acoustic emission of the flame. Only the acoustic emission of the unconfined swirl flame could be computed by the heat release source. To accurately predict the phase and the amplitude of the sound emission of the other flames the acceleration of density gradients occurring at the flame front must be included in the considered set of source terms.

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f^{- 2.1}

is similar to the results reported by Rajaram and Lieuwen [41].…”

Section: Resultssupporting

confidence: 74%

“…The acoustic pressure is measured at a microphone position

r = 30 d

, that is, on the burner outlet plane at a distance of

1.05

m from the centerline. The experiments were done by Nawroth and Paschereit [35] in an anechoic environment.…”

Section: Numerical Configurationsmentioning

confidence: 99%

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Analysis of the sound sources of lean premixed methane–air flames

et al. 2021

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“…3 D illustration of the jet burner facility 37 (a) and 2 D schematic of the burner (b). The origin of the coordinate system (y,r)=(0D,0D) is located in the center of the nozzle exit of the plenum.…”

Section: Experimental Burner Configurationmentioning

confidence: 99%

“…Therefore, in this study an unconfined turbulent flame of a generic burner described in Nawroth and Paschereit 37 is investigated. Turbulent flames contain a broad spectrum of pressure fluctuations such that several acoustic modes of the burner plenum can be excited.…”

Section: Introductionmentioning

confidence: 99%

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

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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.

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