Mixing and combustion in turbulent gas jets

Hawthorne, W. R.; Weddell, David Stover; Hottel, H.C.

doi:10.1016/s1062-2896(49)80035-3

Cited by 162 publications

(107 citation statements)

References 5 publications

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“…Hawthorne, Weddell & Hottel (1949), for instance, introduced the concept of 'unmixedness' and emphasized the need for an understanding of the molecular mixing processes. They J .…”

Section: Discussion Of Related Studiesmentioning

confidence: 99%

A simple model of mixing and chemical reaction in a turbulent shear layer

1982

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Arguments are presented to show that the concept of gradient diffusion is inapplicable to mixing in turbulent shear layers. A new model is proposed for treating molecular mixing and chemical reaction in such flows a t high Reynolds number. It is based upon the experimental observations that revealed the presence of coherent structures and that showed that fluid elements from the two streams are distributed unmixed throughout the layer by large-scale inviscid motions. The model incorporates features of the strained flame model and makes use of the Kolmogorov cascade in scales. Several model predictions differ markedly from those of diffusion models and suggest experiments for testing the two approaches.

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“…Hawthorne, Weddell & Hottel (1949), for instance, introduced the concept of 'unmixedness' and emphasized the need for an understanding of the molecular mixing processes. They J .…”

Section: Discussion Of Related Studiesmentioning

confidence: 99%

A simple model of mixing and chemical reaction in a turbulent shear layer

1982

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“…Data have been extracted from 34 publications, ranging from the pioneering works of Hawthorne et al [11], and Wohl et al [12] in 1949, to the recent unique high altitude propane data of Hu et al [13] and Wang et al [14], collected in Lhasa at ambient pressures down to 60 kPa. The studies of hydrogen jet flames have involved inlet pipe pressures up to 90 MPa.…”

Section: Experimental Datamentioning

confidence: 99%

“…McCaffrey showed it could be used outside the buoyancy and pool fire regimes to correlate H/D over surprisingly broad regimes, including turbulent jet flames. The original correlation was presented as logarithmic plots of H/D against Q* 2/5 [3] and employed the experimental data in [11,24,33,[35][36][37][38][39]. Becker and Liang's data correlation [35] are shown on the present figure, as Q* attained 2·10 7 .…”

Section: The Q* Parametermentioning

confidence: 99%

Jet flame heights, lift-off distances, and mean flame surface density for extensive ranges of fuels and flow rates

Bradley

Gaskell

et al. 2016

Combustion and Flame

105

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An extensive review and re-thinking of jet flame heights and structure, extending into the choked/supersonic regime is presented, with discussion of the limitations of previous flame height correlations. Completely new dimensionless correlations for the plume heights, lift-off distances, and mean flame surface densities of atmospheric jet flames, in the absence of a cross wind, are presented. It was found that the same flow rate parameter could be used to correlate both plume heights and flame lift-off distances. These are related to the flame structure, jet flame instability, and flame extinction stretch rates, as revealed by complementary experiments and computational studies. The correlations are based on a vast experimental data base, covering 880 flame heights. They encompass pool fires and flares, as well as choked and unchoked jet flames of CH 4 , C 2 H 2 , C 2 H 4 , C 3 H 8 , C 4 H 10 and H 2 , over a wide range of conditions. Supply pressures range from 0.06 to 90MPa, discharge diameters from 4·10 -4 to 1.32 m, and flame heights from 0.08 to 110 m. The computational studies enabled reaction zone volumes to be estimated, as a proportion of the plume volumes, measured from flame photographs, and temperature contours. This enabled mean flame surface densities to be estimated, together with mean volumetric heat releases rates. There is evidence of a "saturation" mean surface density and increases in turbulent burn rates being accomplished by near pro rata increases in the overall volume of reacting mixture.

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“…Hawthorne et al [10] In 1984 Kalghatgi [11] published jet flame lengths for more than 70 tests with subsonic and sonic releases of hydrogen into still air through nozzles with diameter from 1.08 to 10.1 mm. Each burner was a straight tube mounted at the end of a settling chamber of internal diameter 152 mm.…”

Section: Description and Interpretation Of Experimentsmentioning

confidence: 99%

The Correlation for Non-premixed Hydrogen Jet flame Length in Still Air

Molkov¹,

Saffers²

2011

Fire Safety Science - Proceedings of the 10th International Sym

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The experimental data on the hydrogen flame length normalized by the nozzle diameter are correlated with the dimensionless product of the density ratio (hydrogen density in the nozzle exit to the density of surrounding air) and the Mach number to the power of three. The current up-to-date experimental data on hydrogen flame length are used to build the correlation that covers laminar and turbulent flows, buoyancyand momentum-dominated releases, subsonic, sonic and highly under-expanded supersonic jets. The density and velocity of hydrogen in the nozzle are taken either directly from experiments or calculated by the under-expanded jet theory published elsewhere. The correlation is validated in the range of hydrogen storage pressures from nearly atmospheric up to 90 MPa and nozzle diameters from 0.4 to 51.7 mm. The predictive capability of this dimensionless correlation exceeds that of previously published work based on the Froude number only.KEYWORDS: hydrogen jet fire, flame length, under-expanded jet. NOMENCLATURE LISTING

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Mixing and combustion in turbulent gas jets

Cited by 162 publications

References 5 publications

A simple model of mixing and chemical reaction in a turbulent shear layer

A simple model of mixing and chemical reaction in a turbulent shear layer

Jet flame heights, lift-off distances, and mean flame surface density for extensive ranges of fuels and flow rates

The Correlation for Non-premixed Hydrogen Jet flame Length in Still Air

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