Reaction layer visualization: A comparison of two PLIF techniques and advantages of kHz-imaging

Skiba, A.; Wabel, Timothy M.; Carter, Campbell D.; Hammack, Stephen D.; Temme, Jacob; Lee, Tonghun; Driscoll, James F.

doi:10.1016/j.proci.2016.07.033

Cited by 41 publications

(13 citation statements)

References 36 publications

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“…Following those corrections, the PLIF images were subjected to a self-guided [12] and a median filter with 5 × 5 pixels 2 and 3 × 3 pixels 2 kernels, respectively, resulting in SNRs of ∼15 and ∼8 for OH and CH 2 O, respectively. Next, the OH-PLIF images were registered to the CH 2 O-PLIF or vector field images [13,14]. Finally, as in prior studies of turbulent premixed flames (see, for example, Refs.…”

Section: Methodsmentioning

confidence: 99%

On the bi-stable nature of turbulent premixed bluff-body stabilized flames at elevated pressure and near lean blow-off

Skiba

Guiberti

Boyette

et al. 2021

Proceedings of the Combustion Institute

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Section: Methodsmentioning

confidence: 99%

On the bi-stable nature of turbulent premixed bluff-body stabilized flames at elevated pressure and near lean blow-off

Skiba

Guiberti

Boyette

et al. 2021

Proceedings of the Combustion Institute

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“…in gas turbines [14], exhibits different turbulence-chemistry interactions compared to fuel-rich (Φ = 6.0) moderate or intense low-oxygen dilution (MILD) combustion used in furnaces. Zhou et al [15][16][17][18] [19] and Wabel et al [20,21] did not observe any substantial broadening of the heat release layer for lean (Φ = 0.65 and 0.75) and close-to stoichiometric (Φ = 1.05) methane/air flames using the Michigan Hi-Pilot burner. However, significant broadening of the preheat layer was observed and it was suggested that the elevated viscosity attenuates the turbulence.…”

Section: Introductionmentioning

confidence: 93%

Quantification of combustion regime transitions in premixed turbulent DME flames

Hampp

Lindstedt

2017

Combustion and Flame

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The current study quantifies the probability of encountering up to five fluid states (reactants, combustion products, mixing fluid, fluids with low and high reactivity) in premixed turbulent DME flames as a function of the Damköhler number. The flames were aerodynamically stabilised in a back-to-burnt opposed jet configuration featuring fractal grid generated multi-scale turbulence (Re≃ 18,400 and Ret > 370). The chemical timescale was varied via the mixture stoichiometry resulting in a wide range of Damköhler numbers (0.08 ≤ Da ≤ 5.6). The mean turbulent strain (≥ 3200 s−1) exceeded the extinction strain rate of the corresponding laminar flames for all mixtures. Simultaneous Mie scattering, OH-PLIF and PIV were used to identify the fluid states and supporting computations show that the thermochemical state (e.g. OH and CH concentrations) at the twin flame extinction point correlates well with flames in the back-to-burnt geometry at the corresponding rate of heat release. For mixtures where the bulk strain (≃ 750 s−1) was similar to (or less than) the extinction strain rate, fluids with low and high reactivity could accordingly be segregated by a threshold based on the OH concentration at the extinction point. A sensitivity analysis of the distribution between the fluid states was performed. The flow conditions were further analysed in terms of Damköhler and Karlovitz numbers. The study provides (i) the evolution of multi-fluid probability statistics as a function of the Damköhler number, including (ii) the flow direction across fluid interfaces and OH gradients, (iii) mean flow field statistics, (iv) conditional velocity statistics and (v) a tentative combustion regime classification

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“…Various models have been proposed to account for this phenomenon [34,36], although very limited experimental measurements have been performed for validation of these models. Skiba et al [42] used high-speed CH-PLIF imaging of reaction layers to experimentally quantify the merging rate of flamelets to provide some insights on the destruction rate of FSD in a round Bunsen turbulent flame. There were uncertainties in the interaction identification algorithm in their study, and results…”

Section: Dnsmentioning

confidence: 99%

“…It is likely that the presence of adjacent interacting flowfields alters the mean shear in the case of dual-flames that can change the local flow dynamics and impact the local flame-flame interaction statistics [54]; this interaction is absent in the single-flame cases.The measurement techniques employed in this study are limited to imaging the in-plane components of flame-flame interactions. As flame-flame interactions are inherently threedimensional, it is necessary to rigorously estimate the effect of through-plane velocity and flame surface orientation[42]. While exact quantification of these uncertainties may require full threedimensional measurements of the flame surface, we provide an estimate of the out-of-plane fluid motion at the interaction locations using s-PIV measurements.…”

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confidence: 99%

Statistics and topology of local flame–flame interactions in turbulent flames

Tyagi

Boxx

Peluso

et al. 2019

Combustion and Flame

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Flame-flame interaction events occur frequently in turbulent premixed flames and change the local structure and dynamics of flames. It is essential to understand these flame-flame interaction events to develop high-fidelity combustion models for use in modern combustion devices. In this study, we experimentally investigate the topology of flame-flame interaction events in single-and multi-flame configurations. A dual-burner experiment is probed with highspeed OH-planar laser-induced fluorescence and stereoscopic-particle image velocimetry to obtain simultaneous flame front locations and velocity fields. A non-rigid image registration technique is implemented to track the topological changes occurring in these flames. In both single-and dualflame configurations, small-scale interactions occur more frequently compared to large-scale interactions, and statistics show that most of the reactant-side interactions contribute to large flame surface destructions than the product-side interactions. It is also found that turbulence length-and velocity-scales can play an important role in facilitating the interaction events and pocket formations from these events. Filamentarity is used to quantify the two-dimensional shape of these interactions and comparisons are made between the orientation and shape of interaction events and the local turbulence in the flowfield. Alignment between the orientation of the interaction shapes and the principal strain rates show that compressive fluid forces drive both types of interaction events. Δ Angle difference between and ℱ Filamentarity ℛ Reactant-side interaction rates ℛ Pocket formations from reactant-side interactions ℛ Product-side interaction rates ℛ Pocket formations from product-side interactions

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Reaction layer visualization: A comparison of two PLIF techniques and advantages of kHz-imaging

Cited by 41 publications

References 36 publications

On the bi-stable nature of turbulent premixed bluff-body stabilized flames at elevated pressure and near lean blow-off

On the bi-stable nature of turbulent premixed bluff-body stabilized flames at elevated pressure and near lean blow-off

Quantification of combustion regime transitions in premixed turbulent DME flames

Statistics and topology of local flame–flame interactions in turbulent flames

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