Blowoff mechanism of two dimensional bluff-body stabilized turbulent premixed flames in a prototypical combustor

Chaudhuri, Swetaprovo; Kostka, Stanislav; Tuttle, Steven G.; Renfro, Michael W.; Cetegen, Baki M.

doi:10.1016/j.combustflame.2010.11.012

Cited by 86 publications

(13 citation statements)

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“…It was found that upstream propagation (flashback) of a premixed flame tip is associated to the flame tip eccentricity, which is a direct result of PVC along the centerline at the burner exit [61]. In addition, vortex shedding is found to reappear prior to flame blowout [62] and can cause local extinction [63]. PVC most likely occurs on the central recirculation zone (CRZ) boundaries when, for example, a swirl number exceeds 0.6 [64].…”

Section: Progress and Challenges Of Ppfsmentioning

confidence: 99%

Burner geometry effect on coherent structures and acoustics of a confined swirling partially premixed methane flame

Ahmed

Birouk

2019

Experimental Thermal and Fluid Science

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The effect of burner geometry (central fuel nozzle, mixing tube length, and flame confinement) on the ensuing flowfield's coherent structures (precessing vortex core and vortex shedding) and their relationship with some combustion stability parameters, such as flashback and flame front dynamics of a swirling partially premixed methane flame, is experimentally studied. In this investigation, several measurement techniques are employed. These include particle image velocimetry (PIV), Mie scattering, laser Doppler velocimetry (LDV), Bruel & Kjaer microphone, high-speed Schlieren imaging technique, and high-speed luminescence imaging. In addition, proper orthogonal decomposition (POD) is used as a post processing technique to capture the flowfield coherent structures. In the first part of the study, the effect of central nozzle geometry on coherent structures' strength and frequency is examined inside a relatively long mixing tube.

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Section: Progress and Challenges Of Ppfsmentioning

confidence: 99%

Burner geometry effect on coherent structures and acoustics of a confined swirling partially premixed methane flame

Ahmed

Birouk

2019

Experimental Thermal and Fluid Science

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“…Second, we focus on the large-scale dynamics of these flow fields, which can influence both largescale and small-scale processes in technologies with interacting flows. The presence of coherent structures has been shown to enhance mixing on a local scale [29], while large-scale dynamics can significantly impact system performance; in combustors, large-scale structures drive limiting processes such as blowoff [30] and combustion instability [31], and in structural configurations, large-scale motions can drive high-cycle fatigue. In particular, we are interested in the variations in frequency and symmetry of these dynamics.…”

Section: Scope Of This Studymentioning

confidence: 99%

Flow dynamics in a variable-spacing, three bluff-body flowfield

2018

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This work explores the wake dynamics of systems with three bluff bodies with variable spacing. Studies of single-wake systems have shown that coherent wake vortices have a regular, and predictable, periodicity. A growing literature of dual-wake studies has shown that multi-wake systems are more stochastic than single-wake systems, and their dynamics are highly dependent on the spacing between the wakes. Here, we expand on this literature by investigating three-wake systems, and find that the coherent dynamics of the wakes are highly intermittent. We use proper orthogonal decomposition to extract the most energetic modes of the three-wake system at six bluff-body spacings that span a range of dynamical "regimes." After describing the time-dependent behavior of the interacting wakes in these regimes, we use a statistical approach to describe the relative phase between oscillations in each of the wakes, identifying regimes where oscillations are more or less random. Interestingly, the wake oscillations are less random when the bluff bodies are positioned very close and relatively far from each other. In between these two extremes, an intermediary regime is identified where the wake oscillations are almost completely random; this finding parallels data from the dual-wake literature. Finally, we discuss the implications of the observed behaviors and possible future directions for this work. I. INTRODUCTION The goal of this paper is to characterize transitions in flow development and stability characteristics with variations in bluff-body spacing in a three bluff-body flow field. The applications of this work are far reaching, from flame holders in jet engine augmentors, to air moving though power transmission lines, to flows through heat exchangers, to piers supporting trusses in unsteady waters. In each of these applications, adjacent flow fields, or a series of individual wakes, experience a significant level of interaction. The interaction can change both the time-averaged and dynamical characteristics of

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“…High-speed images and acoustic measurements were also recorded near blowout. The data points from these experiments were combined with those obtained from the publications of other authors, including Ballal and Lefebvre, 13 DeZubay, 4 King, 9 Potter and Wong, 34 Williams, 35 Zukoski, 10 and Chaudhuri et al 36 Figure 5 is a summary of the experimental parameters from each study. An input file of more than 850 individual points was created that included the relevant parameters from each study such as inlet conditions and flame-holder characteristics.…”

Section: B Lean Blowouts and Correlation Setupmentioning

confidence: 99%