Shear Layer Dynamics in a Reacting Jet in Crossflow

Nair, Vedanth; Wilde, Benjamin; Emerson, Benjamin; Lieuwen, Tim

doi:10.1016/j.proci.2018.06.031

Cited by 37 publications

(13 citation statements)

References 23 publications

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“…The heat release is concentrated in the region where shear-layer vortices appear, impacting the unsteady development and evolution of these vortices as demonstrated by figure 1 and also reported for other studies (Nair et al. 2019 b ; Pinchak et al. 2019).…”

Section: Resultssupporting

confidence: 75%

Frequency response analysis of a (non-)reactive jet in crossflow

Sayadi

Schmid

2021

J. Fluid Mech.

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Section: Resultssupporting

confidence: 75%

Frequency response analysis of a (non-)reactive jet in crossflow

Sayadi

Schmid

2021

J. Fluid Mech.

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“…This complicates the interpretation of combustion effects across cases with different flame configurations where the local effect of combustion will be different. For example, even when combustion was noted to have a significant effect on suppressing the growth rate of SLV structures (Nair et al 2019), this effect was limited in cases where the windward branch of the flame was lifted. Dominant mechanisms for combustion influences on the flow dynamics can be understood from studies focused on other canonical flow configurations.…”

Section: Introductionmentioning

confidence: 99%

Combustion and flame position impacts on shear layer dynamics in a reacting jet in cross-flow

et al. 2022

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This study experimentally investigates reacting jets in cross-flow (RJICF), considering flame/shear layer offset, momentum flux ratio ( $J$ ) and density ratio ( $S$ ) effects. These results demonstrate that non-reacting JICF and RJICF can exhibit very similar or completely different dynamics and controlling physics, depending upon streamwise and radial flame location. Consistent with prior measurements of Getsinger et al. (Exp. Fluids, vol. 53 (3), 2012, pp. 783–801), spatial amplification rates of shear layer vortex (SLV) structures increased with decreasing $S$ for non-reacting cases. Similar $S$ dependencies exist for reacting cases in which the flame lay outside the jet shear layer, whose flow topology is also quite similar to non-reacting cases, albeit with reduced SLV growth rates. However, although the reacting cases have lower growth rates, these SLV structures ultimately reach approximately the same peak strength as in the non-reacting cases. Finally, the SLV decay rate in both non-reacting and reacting cases was found to similarly scale inversely with the initial SLV growth rate. As such, primarily inertial mechanisms govern SLV growth and decay for reacting cases where the flame lies outside the shear layer. In contrast, very different behaviour is exhibited by reacting cases where the flame lies inside the shear layer, where the locally increased viscosity exerts significant influences. In these reacting cases, SLV roll-up is completely suppressed and the entire jet column undulates over a long length scale relative to the jet diameter. As such, the relative roles of inertial and viscous mechanisms in controlling combustion influences on the SLV dynamics, changes markedly with shear layer–flame offset.

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“…Most of the research on RJICF has been oriented towards experimental non-premixed configurations, injecting either pure gaseous fuel or oxidizer into a transverse flow [3,4,5,6,7,8,9,10]. In this type of configurations, the mixing process between fuel and oxidizer is dominated by the shear layer dynamics and it is critical for the ignition and stabilization of the flame.…”

Section: Introductionmentioning

confidence: 99%

“…Sullivan et al [6] found experimental ignition times and locations to be of similar order of magnitude as those computed with 0D reactor simulations. Lyra et al [7] and Nair et al [10] investigated the dynamics of the leeward and windward flame branches of a hydrogen-helium jet. Non-premixed flame structures were found to dominate the high heat-release regions after ignition and a strong interplay between flame stabilization location and jet shear layer aerodynamic stability.…”

Section: Introductionmentioning

confidence: 99%

Morphology and Dynamics of a Premixed Hydrogen-Methane-Air Jet Flame in Hot Vitiated Turbulent Crossflow

Solana-Pérez

Miniero

Shcherbanev

et al. 2020

Volume 4B: Combustion, Fuels, and Emissions

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The effect of hydrogen enrichment of a premixed hydrogen-methane-air jet in hot vitiated crossflow was studied at atmospheric condition. The hot turbulent vitiated crossflow is generated by a symmetric array of 4 × 4 jet flames burning a lean mixture of natural gas and air in fully premixed condition at equivalence ratio φcf = 0.7 and total thermal power of 50 kW. This crossflow is then used to ignite the premixed perpendicular jet of hydrogen-methane-air at ambient temperature. Three jet parameters are varied to study the effect of hydrogen addition on the flame morphology and stabilization mechanism: the hydrogen mass fraction of the H2/CH4 fuel blend (ξ = 0 – 100%), the jet equivalence ratio (φ = 0.8 – 2.0) and the jet-to-crossflow momentum ratio (J = 3 – 12). High-speed hydroxyl (OH) chemiluminescence is used to obtain the time-resolved imaging of the reactive jet and to compute its time averaged morphology. OH planar laser induced fluorescence (OH-PLIF) is used to acquire OH concentration fields at the jet center plane. The jet morphology is analyzed by considering its mean trajectory, extracted from the experimental data and fitted with empirical correlations available from the literature. New correlations are proposed for the flame length, width and center of gravity as function of the hydrogen content. It is shown that with increasing hydrogen fraction, the flame is shortened and more compact, and it stabilizes close to the jet root. Another finding of this work is the reattachment of the flame at the base of the windward jet shear layer when hydrogen fraction is increased. Robust flame anchoring is observed for H2 mass fractions of the CH4/H2 fuel blend that exceed 50%. Moreover, it is shown using instantaneous OH-PLIF images that for these conditions of increasing hydrogen concentration, the windward shear layer features larger-scale coherent structures that govern the aerodynamics of the reactive premixed jet in turbulent vitiated crossflow.

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Shear Layer Dynamics in a Reacting Jet in Crossflow

Cited by 37 publications

References 23 publications

Frequency response analysis of a (non-)reactive jet in crossflow

Frequency response analysis of a (non-)reactive jet in crossflow

Combustion and flame position impacts on shear layer dynamics in a reacting jet in cross-flow

Morphology and Dynamics of a Premixed Hydrogen-Methane-Air Jet Flame in Hot Vitiated Turbulent Crossflow

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