Flame self-interactions in an open turbulent jet spray flame

Malkeson, Sean P.; Ahmed, Umair; Pillai, Abhishek L.; Chakraborty, Nilanjan; Kurose, Ryoichi

doi:10.1063/5.0039155

Cited by 7 publications

(2 citation statements)

References 54 publications

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“…In general, tunnel-type topologies dominate, although short peaks of UPs can be seen during shock-flame interactions in both cases. Similar observations have been made in the analysis of an open turbulent jet spray flame, where TCs and TFs are found to be the predominant topologies 28 . For and also in the nonreactive cases, an equilibrium state is reached, where the tunnel-type (pocket-type) topologies each make up ( ) of total FSI topologies, which can be explained by the intermixing of small pockets of burned and unburned gas throughout the lean flame.…”

Section: Resultssupporting

confidence: 83%

Surface topologies and self interactions in reactive and nonreactive Richtmyer–Meshkov instability

Bambauer

Haßlberger

Ozel-Erol

et al. 2023

Sci Rep

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The reactive Richtmyer–Meshkov instability (RMI) exhibits strong wrinkling of a reactive flame front after an interaction with a shock wave. High levels of deformation and wrinkling can cause the flame surface to intersect with itself, leading to the events of flame self interactions (FSI). As FSI can have a significant influence on the development and topology of the flame surface, it should be considered an important factor affecting the burning characteristics of the flame. The topological structure and statistics of FSI are analyzed using data from high-fidelity simulations of a planar shock wave interacting with a statistically planar hydrogen/air flame for stoichiometric, lean and nonreactive gas mixtures. FSI events are detected by searching for critical points in the field of the reaction progress variable c and divided into the following topological categories: burned gas mixture pocket (BP), unburned gas mixture pocket (UP), tunnel formation (TF) and tunnel closure (TC). It is found that reactivity and flame thickness are decisive factors, influencing the frequency and topological distribution of the detected FSI events. While in early RMI-stages the FSI is found to be mainly dependent on the flame thickness, later stages are heavily influenced by the reactivity, as high reactivity quickly burns out emerging wrinkled structures (in the stoichiometric case) leading to massively reduced levels of FSI. The findings are further supported by the results from the nonreactive case, which at later stages of the RMI closely resembles the less reactive lean case. Analysis of the topology distribution over time and conditioned over c, reveals further differences between the lean and stoichiometric case, as the strong wrinkling and mixing encountered with the lean case facilitates the build up of many pocket-type and tunnel-type interactions throughout the wrinkled flame front. For the stoichiometric case, mainly tunnel-type and unburned pocket topologies are found in the narrow flame funnels extending into the burned gas.

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Section: Resultssupporting

confidence: 83%

Surface topologies and self interactions in reactive and nonreactive Richtmyer–Meshkov instability

Bambauer

Haßlberger

Ozel-Erol

et al. 2023

Sci Rep

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“…These contributions are on diverse topics including combustion instability, 150,151 scalar mixing, [152][153][154][155][156] homogeneous isotropic turbulence, [157][158][159][160] turbulent premixed flames, [161][162][163][164][165][166][167][168][169][170][171] turbulent non-premixed flames, [172][173][174][175] wallbounded turbulence, [176][177][178] turbulent combustion modeling, [179][180][181] FDF/PDF, [182][183][184][185][186][187][188][189][190][191][192] and two-phase turbulent flows. [193][194][195][196][197][198]…”

Section: Organization Of This Simentioning

confidence: 99%

Edward E. O'Brien contributions to reactive-flow turbulence

2021

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Professor Edward Ephraim O'Brien ("Ted") has made lasting contributions to the theory and modeling of scalar mixing and reaction in turbulent flows. With a doctoral dissertation at The Johns Hopkins University in 1960, entitled "On the Statistical Behavior of a Dilute Reactant in Isotropic Turbulence," supervised by the legend Stanley Corrsin, and in the company of notable pioneer of turbulence, John Leask Lumley, Ted's academic training propelled him through a prolific career. In the opening article of this Special Issue, we provide a review of some of Ted's contributions. First, a summary is presented of his work on the examination of the failure of the cumulant discard approximation for the scalar mixing. This is followed by a highlight of his impacts on other spectral theories of turbulence including Kraichnan's direct interaction approximation. His contributions to more modern theoretical/computational description of reactive turbulence are discussed next, including the transported probability density function (pdf) formulation, scalar-gradient pdf transport equation, scalar interfaces, and the filtered density function. Finally, some of his research on Direct Numerical Simulation of compressible turbulence is reviewed.

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Flame Self-interaction and Flow Topology in Turbulent Homogeneous Mixture n-Heptane MILD Combustion

Abo-Amsha

Chakraborty

2023

Flow Turbulence Combust

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Moderate or Intense Low-oxygen Dilution (MILD) combustion has potential to achieve both high energy efficiency and ultra-low emissions. This analysis adopts the critical point theory to characterise the Flame-Self Interaction (FSI) events and flow topologies in turbulent, homogeneous mixture, n-Heptane MILD combustion using Direct Numerical Simulations (DNS) with reduced chemical mechanism. The local flame geometry has also been categorised using the mean and Gauss curvatures. It was found that the Tunnel Formation (TF) and Tunnel Closure (TC) topologies are the most probable FSI events at all values of the reaction progress variable c, while the Unburned Pocket (UP) and Burned Pocket (BP) topologies were mostly present towards the unburned and burned mixtures of the flame, respectively. Moreover, increasing the turbulence intensity did not result in any significant changes in the distribution of FSI events. Investigation of the flow topology distribution showed that the features associated with non-zero dilatation rate did not exist in the MILD cases considered. This is a consequence of the negligible thermal expansion effect due to the small temperature rise in MILD combustion cases. Increasing the dilution factor caused a reduction in the frequency of FSI events for all c levels. The distributions of flame self-interaction events in homogeneous mixture MILD combustion have been found to be significantly different from previously reported distributions for conventional turbulent premixed combustion.

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Flame self-interactions in an open turbulent jet spray flame

Cited by 7 publications

References 54 publications

Surface topologies and self interactions in reactive and nonreactive Richtmyer–Meshkov instability

Surface topologies and self interactions in reactive and nonreactive Richtmyer–Meshkov instability

Edward E. O'Brien contributions to reactive-flow turbulence

Flame Self-interaction and Flow Topology in Turbulent Homogeneous Mixture n-Heptane MILD Combustion

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