3D flame topography and curvature measurements at 5 kHz on a premixed turbulent Bunsen flame

Ma, Lin; Wu, Yue; Lei, Qingchun; Xu, Wenjiang; Carter, Campbell D.

doi:10.1016/j.combustflame.2015.12.031

Cited by 49 publications

(11 citation statements)

References 43 publications

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“…There are numerous studies on the effects of strain and curvature on premixed flames (e.g. Matalon & Matkowsky [1982], Clavin & Joulin [1983], Searby & Quinard [1990], ), , Najm & Wyckoff [1997], Chen & Im [1998], Peters et al [1998], , Chen et al [1999], Chen & Im [2000, Bechtold & Matalon [2001], Durox et al [2001], Haq et al [2002], Sinibaldi et al [2003], Chakraborty & Cant [2004, Hawkes & Chen [2004], Chakraborty & Cant [2005, Hawkes & Chen [2005], Hawkes & Chen [2006], Kerl et al [2013], Fogla et al [2015], Sankaran et al [2015, Ma et al [2016]). This subject is of fundamental interest since the flame response to instabilities are modified by these effects.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

Sound generation by turbulent premixed flames

et al. 2018

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“…To the best of our knowledge, the work of Anikin et al [3,4] is so far the only study that uses Tikhonov regularization for the tomographic imaging of laminar and turbulent flames. The vast majority of tomographic studies on combustion processes uses either the algebraic reconstruction technique (ART) [6,7,[10][11][12][13][14][15][16][17]19,20,23,28,29,60] or its sibling, the multiplicative algebraic reconstruction technique (MART) [21,22,25,26,[30][31][32]. ART was developed independently by Gordon, Bender and Herman [49] and Hounsfield [50].…”

Section: Tomographic Reconstructionmentioning

confidence: 99%

“…Floyd et al [6] and Anikin et al [3] were the first to investigate turbulent flames with optical emission tomography. More recently the focus has shifted towards space-and time-resolved tomographic measurements with kHz-repetition rate [8,13,15,17,25,28,29,31].…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Tomographic Simultaneous Multispecies Visualization—Part II: Reconstruction Accuracy

2020

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Recently we demonstrated the simultaneous detection of the chemiluminescence of the radicals OH* (310 nm) and CH* (430 nm), as well as the thermal radiation of soot in laminar and turbulent methane/air diffusion flames. As expected, a strong spatial and temporal coupling of OH* and CH* in laminar and moderate turbulent flames was observed. Taking advantage of this coupling, multispecies tomography enables us to quantify the reconstruction quality completely independent of any phantom studies by simply utilizing the reconstructed distribution of both species. This is especially important in turbulent flames, where it is difficult to separate measurement noise from turbulent fluctuations. It is shown that reconstruction methods based on Tikhonov regularization should be preferred over the widely used algebraic reconstruction technique (ART) and multiplicative algebraic reconstruction techniques (MART), especially for high-speed imaging or generally in the limit of low signal-to-noise ratio.

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“…Unweighted surface-averaged quantities appear to be addressed in experimental papers aiming at evaluation of, e.g., local flame thickness [49][50][51][52][53][54][55] by measuring |∇c|, local flame curvature κ [54][55][56][57], or local strain rate a t [58].…”

Section: Introductionmentioning

confidence: 99%

Surface-averaged quantities in turbulent reacting flows and relevant evolution equations

Lipatnikov

2019

Phys. Rev. E

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While quantities conditioned to an isosurface of reaction progress variable c, which characterizes fluid state in a turbulent reacting flow, have been attracting rapidly growing interest in the recent literature, a mathematical and physical framework required for research into such quantities has not yet been elaborated properly. This paper aims at filling two fundamental gaps in this area, i.e., (i) ambiguities associated with a definition of a surface-averaged quantity and (ii) the lack of rigorous equations that describe evolutions of such quantities. In the first (theoretical) part of the paper, (a) analytical relations between differently defined (area-weighted and unweighted) surface-averaged quantities are obtained and differences between them (quantities) are discussed, (b) a unified method for deriving an evolution equation for bulk area-weighted surface-averaged value of a local characteristic φ of a turbulent reacting flow is developed, and (c) the method is applied for deriving evolution equations for the bulk area-weighted surface-averaged reaction-surface density |∇c|, local reactionwave thickness 1/|∇c|, and local displacement speed S d , i.e., the speed of an isosurface of the c(x, t) field with respect to the local flow. In the second (numerical) part of the paper, direct numerical simulation data obtained recently from a highly turbulent reaction wave are analyzed in order to (1) highlight substantial differences between area-weighted and unweighted surface-averaged quantities and (2) show that various terms in the derived evolution equations are amenable to accurate numerical evaluation in spite of appearance of the so-called zero-gradient points [C. H. Gibson, Phys. Fluids 11, 2305 (1968)] in a highly turbulent medium. Finally, the obtained analytical and numerical results are used to shed light on the paradox of local flame thinning and broadening which is widely discussed in the turbulent combustion literature.

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3D flame topography and curvature measurements at 5 kHz on a premixed turbulent Bunsen flame

Cited by 49 publications

References 43 publications

Sound generation by turbulent premixed flames

Sound generation by turbulent premixed flames

Two-Dimensional Tomographic Simultaneous Multispecies Visualization—Part II: Reconstruction Accuracy

Surface-averaged quantities in turbulent reacting flows and relevant evolution equations

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