Investigation of Jet-Flame Blowout with Lean-Limit Considerations

Moore, N. J.; Kribs, James D.; Lyons, Kent

doi:10.1007/s10494-011-9334-3

Cited by 15 publications

(9 citation statements)

References 15 publications

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“…With the coflow remaining vertical, this component diminishes as the nozzle angle increases towards the horizontal-that is, less of the coflow blows along the flame and contributes to liftoff/blowout behavior. The effective coflow velocity follows the equation below, as presented originally by Kalghatgi and recently by Moore et al [11,17]. The effective velocity depends on the fuel and air densities, as well as the ambient and coflow velocities:…”

Section: Resultsmentioning

confidence: 97%

Stability and Blowout Behavior of Jet Flames in Oblique Air Flows

Gomes

Kribs

Lyons

2012

Journal of Combustion

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The stability limits of a jet flame can play an important role in the design of burners and combustors. This study details an experiment conducted to determine the liftoff and blowout velocities of oblique-angle methane jet flames under various air coflow velocities. A nozzle was mounted on a telescoping boom to allow for an adjustable burner angle relative to a vertical coflow. Twentyfour flow configurations were established using six burner nozzle angles and four coflow velocities. Measurements of the fuel supply velocity during liftoff and blowout were compared against two parameters: nozzle angle and coflow velocity. The resulting correlations indicated that flames at more oblique angles have a greater upper stability limit and were more resistant to changes in coflow velocity. This behavior occurs due to a lower effective coflow velocity at angles more oblique to the coflow direction. Additionally, stability limits were determined for flames in crossflow and mild counterflow configurations, and a relationship between the liftoff and blowout velocities was observed. For flames in crossflow and counterflow, the stability limits are higher. Further studies may include more angle and coflow combinations, as well as the effect of diluents or different fuel types.

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Section: Resultsmentioning

confidence: 97%

Stability and Blowout Behavior of Jet Flames in Oblique Air Flows

Gomes

Kribs

Lyons

2012

Journal of Combustion

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“…4, where the flame has a relative large angle θ [close to 90] from the jet direction, and the blow-out is mainly dominated by the cross flow). It was reported that the effective velocity [6][7][8], which combines the effects from the fuel jet and the co-flow, can be calculated as eff e e co co…”

Section: A Physical Model Based On the Damköhler Numbermentioning

confidence: 99%

“…Broadwell et al [5] proposed a large-scale mixing model and defined as a criterion of the ratio between the chemical reaction time and the turbulent mixing time to characterize the stability of turbulent diffusion flames. The effect of coflow air on the blow-out limit was also investigated [6][7][8][9][10][11][12][13][14][15] and an effective velocity was proposed. The effect of coflow air temperature was also studied [16,17].…”

Section: Introductionmentioning

confidence: 99%

Blow-out limits of nonpremixed turbulent jet flames in a cross flow at atmospheric and sub-atmospheric pressures

Wang

Yoon

et al. 2015

Combustion and Flame

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NomenclatureThese results were compared with results from a wind tunnel under standard atmospheric pressure (100 kPa) in Hefei city (altitude 50 m). The size of the fuel nozzles used in the experiments ranged from 3 to 8 mm in diameter and propane was used as the fuel. It was found that the blow-out limit first increased and then decreased as the fuel jet velocity increased in both pressures, however, the blow-out limit of the air speed of the cross flow was much lower under the sub-atmospheric pressure than that under standard atmospheric pressure with the domain of the blow-out limit in a plot of the air speed of the cross flow in relation to the fuel jet velocity shrank as the pressure decreased. A theoretical model was developed to characterize the blow-out limit of nonpremixed jet flames in a cross flow based on a Damköhler number, defined as the ratio between the mixing time and the characteristic reaction time. A satisfactory correlation was obtained that included the effects of the air speed of the crossflow, fuel jet velocity, nozzle diameter and pressure.

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“…With respect to the far flow field, Karbasi and Wierzba [16] conducted experiments of fiâmes near blowout, under the infiuence of diluted cofiow, and found that in comparison to the diluent being added to the fuel stream, diluent in the coflow had a more pronounced effect on blowout. In addition, Moore et al [17] found that using the lean fiammability limit prediction to estimate the highest position of fiame stabilization, prior to blowout, was effective. It was also shown that the blowout criterion, E, could still be applied in diluted fiows, as long as the infiuence of the dilution was taken into account, while calculating the jet velocity [17].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, Moore et al [17] found that using the lean fiammability limit prediction to estimate the highest position of fiame stabilization, prior to blowout, was effective. It was also shown that the blowout criterion, E, could still be applied in diluted fiows, as long as the infiuence of the dilution was taken into account, while calculating the jet velocity [17].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen-Diluted Methane Flames in the Near-and Far-Field

Kribs¹,

Moore²,

Hasan³

et al. 2013

Journal of Energy Resources Technology

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With the increased utilization of multicomponent fuels, such as natural gas and biogas, in industrial applications, there is a need to be able to effectively model and predict the properties of jet flames for mixed fuels. In addition, the interaction of these diluted fuels with outside influences (such as differing levels of coflow air) is a primary consideration. Experiments were performed on methane jet flames under the influence of varying levels of nitrogen dilution, from low Reynolds number lifted regimes to blowout, observing the influence of the nitrogen on lifted flame height and flame chemiluminesence images. These findings were analyzed and compared with existing lifted jet flame relations, such as the flammable region approximation proposed by Tieszen et ai, as well as to undiluted flames. The influence of nitrogen dilution was seen to have an effect on the liftoff height of the flame, as well as the blowout velocity of the flame, but was seen to have a less pronounced effect compared with flames with coflowing air.

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Investigation of Jet-Flame Blowout with Lean-Limit Considerations

Cited by 15 publications

References 15 publications

Stability and Blowout Behavior of Jet Flames in Oblique Air Flows

Stability and Blowout Behavior of Jet Flames in Oblique Air Flows

Blow-out limits of nonpremixed turbulent jet flames in a cross flow at atmospheric and sub-atmospheric pressures

Nitrogen-Diluted Methane Flames in the Near-and Far-Field

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