Effects of Buoyancy on Laminar, Transitional, and Turbulent Gas Jet Diffusion Flames

Bahadori, Mohammad; Stocker, Dennis P.; Vaughan, David F.; Zhou, Libin; Edelman, R. B.

doi:10.1016/b978-0-08-042019-6.50012-4

Cited by 22 publications

(20 citation statements)

References 5 publications

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“…2. Similar to earlier observations of soot-containing nonbuoyant laminar jet diffusion flames [7][8][9][10][11][12]14], present luminous flame shapes could be grouped into closed-tip and opened-tip configurations, which were observed for fuel flow rates smaller and larger than the laminar smoke point fuel flow rate, respectively. Blunt-tipped flames were also observed as fuel flow rates approached the tip-opening condition.…”

Section: Discussionsupporting

confidence: 74%

“…Typical of many past observations of sootcontaining nonbuoyant laminar jet diffusion flames [8][9][10][11][12][13][14], present flame shapes could be grouped into closed-tip and opened-tip configurations, which were observed for fuel flow rates smaller and larger than the laminar smoke point fuel flow rates, respectively. In fact, the tip-opening phenomenon provided a convenient indicator of laminar smoke points for present test conditions because the associated dramatic change of the shape of the flame tip invariably corresponded to the first observations of soot emissions.…”

Section: Flame Appearancementioning

confidence: 97%

“…In spite of potential effects of unsteadiness for the ground-based studies of nonbuoyant laminanyet diffusion flames, however, Cochran and co-workers [4][5][6], Bahadori and co-workers [7][8][9][10][11][12], and Sunderland et al [14] all observed a linear correlation between luminous flame lengths and fuel flow rates, independent of jet exit diameter, for each fuel burning in air. This behavior also is typical of the luminous flame lengths of buoyant round laminar jet diffusion flames [19].…”

mentioning

confidence: 99%

“…Studies following the work of Cochran and coworkers [4][5][6] due to Bahadori and coworkers [7][8][9][10][11][12] sought to resolve potential effects of transient flame development and soot luminosity on measurements of the shape of nonbuoyant round laminar jet diffusion flames using both 2.2 s and 5.2 s drop towers. In order to minimize problems of transient behavior, they ignited the flames shortly after the experimental package was released and observed nearly steady flame shapes near the end of free fall.…”

mentioning

confidence: 99%

“…The objectives of this paper are to document these measurements and to develop a summary of the results, convenient for use by others, based on simplified analysis of nonbuoyant laminar jet diffusion flames. Past measurements of the shapes of nonbuoyant laminar jet diffusion flames have been carried out using either drop towers to provide microgravity environments [4][5][6][7][8][9][10][11][12][13] or aircraft facilities [14] to provide low-gravity environments. The earliest work along these lines was a series of studies of hydrocarbon-fueled laminar jet diffusion flames using a 2.2 s free-fall (drop) tower due to Cochran and co-workers [4][5][6].…”

mentioning

confidence: 99%

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Shapes of nonbuoyant round luminous hydrocarbon/air laminar jet diffusion flames

Lin

Faeth

Sunderland

et al. 1999

Combustion and Flame

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The shapes (luminous flame boundaries) of round luminous nonbuoyant soot-containing hydrocarbon/air laminar jet diffusion flames at microgravity were found from color video images obtained on orbit in the Space Shuttle Columbia. Test conditions included ethylene-and propane-fueled flames burning in still air at an ambient temperature of 300 K, ambient pressures of 35-130 kPa, initial jet diameters of 1.6 and 2.7 mm, and jet exit Reynolds numbers of 45-170. Present test times were 100-200 s and yielded steady axisymmetric flames that were close to the laminar smoke point (including flames both emitting and not emitting soot) with luminous flame lengths of 15-63 mm. The present soot-containing flames had larger luminous flame lengths than earlier ground-based observations having similar burner configurations: 40% larger than the luminous flame lengths of soot-containing low gravity flames observed using an aircraft (K.C-135) facility due to reduced effects of accelerative disturbances and unsteadiness; roughly twice as large as the luminous flame lengths of sootcontaining normal gravity flames due to the absence of effects of buoyant mixing and roughly twice as large as the luminous flame lengths of soot-free low gravity flames observed using drop tower facilities due to the presence of soot luminosity and possible reduced effects of unsteadiness. Simplified expressions to estimate the luminous flame boundaries of round nonbuoyant laminar jet diffusion flames were obtained from the classical analysis of Spalding (1979); this approach provided successful correlations of flame shapes for both soot-free and soot-containing flames, except when the soot-containing flames were in the opened-tip configuration that is reached at fuel flow rates near and greater than the laminar smoke point fuel flow rate.

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Section: Discussionsupporting

confidence: 74%

Section: Flame Appearancementioning

confidence: 97%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Shapes of nonbuoyant round luminous hydrocarbon/air laminar jet diffusion flames

Lin

Faeth

Sunderland

et al. 1999

Combustion and Flame

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Combustion processes under microgravity conditions

Williams

Lecture Notes in Physics

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A classification of combustion processes is presented which can be used for discussing influences of microgravity. Profound effects of gravity on combustion arise from the large fractional density changes that generally are associated with combustion. Thus it seems to be rather the rule than the exception that combustion experiments under microgravity conditions reveal previously unanticipated phenomena. A few of these phenomena and their theoretical explanations are presented here. Particular attention is devoted to flame balls and to alcohol droplet combustion. Some accomplishments of these and other microgravity combustion studies are summarized. Finally, combustion topics which appear to hold greatest promise for benefiting from future microgravity experiments are indicated.

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Effect of Oxygen Enrichment in Propane Laminar Diffusion Flames under Microgravity and Earth Gravity Conditions

Bhatia

Singh

2017

Microgravity Sci. Technol.

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Effects of Buoyancy on Laminar, Transitional, and Turbulent Gas Jet Diffusion Flames

Cited by 22 publications

References 5 publications

Shapes of nonbuoyant round luminous hydrocarbon/air laminar jet diffusion flames

Shapes of nonbuoyant round luminous hydrocarbon/air laminar jet diffusion flames

Combustion processes under microgravity conditions

Effect of Oxygen Enrichment in Propane Laminar Diffusion Flames under Microgravity and Earth Gravity Conditions

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