Edge flames in mixing layers: Effects of heat recirculation through thermally active splitter plates

Lu, Zhanbin; Matalon, Moshe

doi:10.1016/j.combustflame.2020.04.010

Cited by 7 publications

(4 citation statements)

References 57 publications

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“…The amplitude and frequency, as well as the nature of the oscillations, vary with D. For example, oscillations of smaller amplitude are seen in (a), while a complex oscillation pattern of multiple frequencies is seen in (b). A closer examination shows that during its motion, the edge flame drags along the trailing diffusion flame, but oscillations along the diffusion flame decay quickly when moving further downstream [23,36]. The oscillations, which begin in the premixed segment of the edge flame, are presumed to share a similar underlying mechanism with the well-known large-Lewis-number pulsation of premixed flames attributed to a diffusive-thermal instability.…”

Section: Symmetric Edge Flamesmentioning

confidence: 89%

“…The case corresponding to r λ = 35 mimics a plate made of glass, while the case corresponding to r λ = 1, i.e., the "virtual-gas" plate, is a hypothetical case of a plate with the same thermo-physical properties as the gas phase. Commonly used materials, such as aluminum and stainless steel, have considerable large values of r λ and have not been analyzed due to the high computational cost, as discussed in [36]. The edge flames in the wake of these four plates are stabilized at different distances, resulting from the extent of thermal interactions with the plates.…”

Section: Thermally Active Splitter Platementioning

confidence: 99%

“…Such a mechanism may explain the favorable effect of certain materials on the stabilization of jet diffusion flames [43,44]. In [36], we provided a quantitative measure that characterizes the heat recirculation and its efficiency, relying not only on the total recirculated heat but also on its distribution along the plate. As an experimentally measurable quantity, it can be exploited in practice for the selection of appropriate nozzle materials that optimize the stabilization of jet diffusion flames.…”

Section: Thermally Active Splitter Platementioning

confidence: 99%

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Anchored and Lifted Diffusion Flames Supported by Symmetric and Asymmetric Edge Flames

Matalon

2023

Symmetry

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Numerous combustion applications are concerned with the stabilization of diffusion flames formed by injecting gaseous fuels into a co-flowing stream containing an oxidizer. The smooth operation of these devices depends on the attachment and lift-off characteristics of the edge flame at the base of the diffusion flame. In this paper, we address fundamental issues pertinent to the structure and dynamics of edge flames, which have attributes of both premixed and diffusion flames. The adopted configuration is the mixing layer established in the wake of a splitter plate where two streams, one containing fuel and the other oxidizer, merge. The analysis employs a diffusive-thermal model which, although it excludes effects of gas expansion, systematically includes the influences of the overall flow rate, unequal strain rates in the incoming streams, stoichiometry, differential and preferential diffusion, heat loss and gas–solid thermal interaction, and their effect on the edge structure, speed, and temperature. Conditions when the edge flame is anchored to the plate, lifted-off and stabilized in the flow, or blown-off, are identified. Two stable modes of stabilization are observed for lifted flames; the edge flame either remains stationary at a specified location or undergoes spontaneous oscillations along a direction that coincides with the trailing diffusion flame.

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Section: Symmetric Edge Flamesmentioning

confidence: 89%

Section: Thermally Active Splitter Platementioning

confidence: 99%

Section: Thermally Active Splitter Platementioning

confidence: 99%

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Anchored and Lifted Diffusion Flames Supported by Symmetric and Asymmetric Edge Flames

Matalon

2023

Symmetry

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“…2019). Lu & Matalon (2019, 2020) investigated the near-wake edge-flame stabilization mechanism, orientation and position of the edge flame in a mixing layer.…”

Section: Introductionmentioning

confidence: 99%

Insights into the flame transitions and flame stabilization mechanisms in a freely falling burning droplet encountering a co-flow

Vadlamudi,

Aravind,

Basu

2023

J. Fluid Mech.

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The present study investigates the flame dynamics of a contactless burning fuel droplet under free fall subjected to a co-flow. The dynamic external relative flow established due to co-flow and droplet acceleration results in a series of droplet flame transitions. Different flame structures were observed, including a wake flame, reversed wake flame and enveloped flame. Following ignition, the droplet is allowed to fall through the central tube of a co-flow arrangement, and, at its exit, the droplet flame encounters the co-flow. The wake flame, which was established based on the droplet's instantaneous velocity of descent, encounters the abrupt relative velocity jump due to the co-flow. This causes the droplet flame to go through various transitions as it approaches equilibrium with the surrounding flow. Once it equilibrates, the droplet flame evolves in response to the instantaneous relative flow velocity. The droplet flame evolves by altering both its shape and the stabilization mechanism. Two stabilization mechanisms were identified for the droplet wake flame: edge-flame stabilization and bluff-body stabilization. The stabilization mechanism for different flame structures and the transition events have been theoretically analysed, and the relation between flame shape evolution and flow velocity has been determined based on the flow-field characteristics at the corresponding Re (Reynolds number) range. Furthermore, these correlations are employed in a mathematical formulation based on the spring–mass analogy, which predicts the droplet flame evolution after encountering the co-flow, including all the transition events.

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Multiplicity of solutions of lifted jet edge flames: Symmetrical and non-symmetrical configurations

Jiménez

Kurdyumov

2023

Combustion and Flame

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Edge flames in mixing layers: Effects of heat recirculation through thermally active splitter plates

Cited by 7 publications

References 57 publications

Anchored and Lifted Diffusion Flames Supported by Symmetric and Asymmetric Edge Flames

Anchored and Lifted Diffusion Flames Supported by Symmetric and Asymmetric Edge Flames

Insights into the flame transitions and flame stabilization mechanisms in a freely falling burning droplet encountering a co-flow

Multiplicity of solutions of lifted jet edge flames: Symmetrical and non-symmetrical configurations

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