Interaction of Two Micro-slot Flames: Heat Release Rate and Flame Shape

Kuwana, Kazunori; Kato, S; Kosugi, Akihiro; Hirasawa, Takashi; Nakamura, Yuji

doi:10.1088/1742-6596/557/1/012079

Cited by 3 publications

(4 citation statements)

References 12 publications

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“…In general, flame length was not significantly affected by interaction ( Figure 15). This differs from the results obtained by other researchers using gas burners, who observed increases in flame length as fires converged [12,54]. However, in their studies, the burning rate was kept constant.…”

Section: Flame Lengthcontrasting

confidence: 92%

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A Study of the Flow Field Surrounding Interacting Line Fires

Maynard¹,

Princevac

Weise

2016

Journal of Combustion

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The interaction of converging fires often leads to significant changes in fire behavior, including increased flame length, angle, and intensity. In this paper, the fluid mechanics of two adjacent line fires are studied both theoretically and experimentally. A simple potential flow model is used to explain the tilting of interacting flames towards each other, which results from a momentum imbalance triggered by fire geometry. The model was validated by measuring the velocity field surrounding stationary alcohol pool fires. The flow field was seeded with high-contrast colored smoke, and the motion of smoke structures was analyzed using a cross-correlation optical flow technique. The measured velocities and flame angles are found to compare reasonably with the predicted values, and an analogy between merging fires and wind-blown flames is proposed.

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Section: Flame Lengthcontrasting

confidence: 92%

“…The probability of merging was primarily a function of window separation, but window dimension also had an effect. Kuwana et al [12] studied the behavior of two adjacent microscale slot flames and noted that the overall heat release increased as burner space decreased, but both flames eventually merged into a unified flame.…”

Section: Introductionmentioning

confidence: 99%

A Study of the Flow Field Surrounding Interacting Line Fires

Maynard¹,

Princevac

Weise

2016

Journal of Combustion

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“…Additionally, microjet configurations are attractive for future micro-power devices due to low soot production and high energy density resulting from a large surface-to-volume ratio. Others have shown that multiple micro-flames may be used to enhance heating performance with special attention to flame-flame interactions that can induce undesirable merging of the individual flames (Hirasawa et al 2012;Kuwana et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of acoustically coupled single- and multi-port jet diffusion flames

Vargas,

Kiani,

Hayrapetyan

et al. 2023

J. Fluid Mech.

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The present experimental study investigated the dynamics of single- and multi-port gaseous jet diffusion flames exposed to acoustic excitation via a standing wave situated in a closed waveguide at atmospheric pressure. High-speed imaging of the oscillatory flame was analysed via proper orthogonal decomposition (POD), revealing distinct signatures in both mode shapes and phase portraits for transitions in the acoustically coupled combustion process. For Reynolds numbers between 20 and 100, and for low to moderate forcing amplitudes, the flame exhibited sustained oscillatory combustion (SOC) that was highly coupled to the acoustic forcing. Frequency analysis of the temporal POD modes accurately recovered the forcing frequency and its higher harmonics. At higher forcing amplitudes, a multi-frequency response was observed, resulting from a combination of the forcing frequency and much lower frequency oscillations due to periodic lift-off and reattachment (PLOR) of the flame, preceding a transition to flame blow-off (BO). For both single- and triple-jet flames, transitions from SOC to PLOR to BO were characterized by significant alterations in primary modal energetic content, deflection and eventual smearing in phase portraits, and the development of additional frequencies in modal spectra, although transitional behaviour for the triple jet flames involved additional complexity in the dynamics due to its structure. These features provide the potential for the development of reduced-order models that can characterize and predict acoustically coupled combustion behaviour.

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“…For a larger length-width ratio, the burner changes from rectangular pool fires to diffusions of micro-slot burners, and the fuel changes from liquid to gaseous fuel, which may be because the liquid fuel is difficult to maintain in the experiment. Kuwana et al [23] studied the heat-release rate and flame shape of two micro-slot flames with a size of 1 mm × 80 mm and found that the total heat-release rate basically increases and that the flame will eventually merge into a unified flame with the decrease in spacing. Hu et al [24] conducted experiments to study the interaction between two identical slot-burners (length: 142.5 mm; width: 2 mm) and developed an analytical model to characterize the critical burner pitch for flame merging.…”

Section: Introductionmentioning

confidence: 99%

Study on Coupled Combustion Behavior of Two Parallel Line Fires

Liu

Yan

et al. 2022

Fire

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In this study, the interaction of two parallel line fires with a length-width ratio of greater than 50 was investigated and compared to a single line fire. Considering different length–width ratios and spacings between the fire sources, experiments were carried out to analyze the fire characteristics, such as the burning rate, the flame-merging state, the flame height, the flame tilt angle, and the flame length of the line fires. Its regularity was revealed by combining two mechanisms, namely, heat feedback enhancement and air entrainment restriction. The results revealed that the burning rate under different length–width ratios shows a uniform law, which increases first and then decreases with a greater spacing between the fire sources. There is a special relationship between the flame-merging probability Pm and the dimensionless characteristic parameters (S/ZC)/(L/d)0.27. Based on this relationship, a critical criterion of flame merging can be obtained as (S/ZC)/(L/d)0.27 = 2.38. In addition, the height and the length of the flame were studied to better describe the flame shape when the flame is tilted. Since the flame is bent, the flame length has an abrupt change at a specific position, and the inclination angle also has the same phenomenon. Finally, it was found that the influence of the length–width ratio on the line fires is relatively limited, which is further weakened under a greater length–width ratio.

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Interaction of Two Micro-slot Flames: Heat Release Rate and Flame Shape

Cited by 3 publications

References 12 publications

A Study of the Flow Field Surrounding Interacting Line Fires

A Study of the Flow Field Surrounding Interacting Line Fires

Dynamics of acoustically coupled single- and multi-port jet diffusion flames

Study on Coupled Combustion Behavior of Two Parallel Line Fires

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