Growth of a freely-propagating, two-dimensional turbulent-like flame

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Using a thin flame model with a constant density ratio across the flame and a constant burning velocity, numerical simulations of flame propagation into defined, non-decaying turbulent-like flow reveals a succession of growth rate behaviors. Starting with laminar growth, the flame length then acquires an exponential growth rate when the turbulence distorts the early flame so that an inner flame radius is a small fraction of the largest outer radius. As the flame continues to grow, the difference between the inner radius and the outer radius, referred to as the flame zone thickness L{sub Z}, becomes constant and small compared ... continued below

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15 p.

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Ashurst, W.T. January 12, 1996.

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  • Sandia National Laboratories
    Publisher Info: Sandia National Labs., Livermore, CA (United States)
    Place of Publication: Livermore, California

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Using a thin flame model with a constant density ratio across the flame and a constant burning velocity, numerical simulations of flame propagation into defined, non-decaying turbulent-like flow reveals a succession of growth rate behaviors. Starting with laminar growth, the flame length then acquires an exponential growth rate when the turbulence distorts the early flame so that an inner flame radius is a small fraction of the largest outer radius. As the flame continues to grow, the difference between the inner radius and the outer radius, referred to as the flame zone thickness L{sub Z}, becomes constant and small compared to the flame size--this yields a constant growth rate, but with magnitude much larger than the initial laminar value. The flame size, using either the average radius or the maximum radius, grows like R {approximately} V{sub C} t, where the flame convection V{sub C} is created by volume expansion distributed throughout the flame zone L{sub Z}. This constant growth rate appears to evolve into a power-law growth rate, R {approximately} t{sup 1+q}, where q > 0, similar to the growth of the flame length, L{sub F} {approximately} t{sup 1+p}, where p > q. which follows its exponential growth period. This accelerated growth rate of flame size can be related to the temporal growth in V{sub C}, which is related to a fractal-like nature of the flame length and a constant flame zone thickness. While there is no direct connection with these synthetic simulations, it is noted that large-scale experiments also exhibit a power-law behavior: R {approximately} t{sup 1.5}.

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15 p.

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OSTI as DE96006815

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  • 26. international symposium on combustion, Naples (Italy), 28 Jul - 2 Aug 1996

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  • Other: DE96006815
  • Report No.: SAND--96-8512C
  • Report No.: CONF-960772--2
  • Grant Number: AC04-94AL85000
  • Office of Scientific & Technical Information Report Number: 233353
  • Archival Resource Key: ark:/67531/metadc673258

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  • January 12, 1996

Added to The UNT Digital Library

  • June 29, 2015, 9:42 p.m.

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  • April 12, 2016, 8:17 p.m.

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Ashurst, W.T. Growth of a freely-propagating, two-dimensional turbulent-like flame, article, January 12, 1996; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc673258/: accessed June 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.