Taylor-diffusion-controlled combustion in ducts
An analysis is presented for the Burke-Schumann flame established when a fuel tank discharges with mean velocity U along a circular duct of radius a filled initially with air. Attention is focused on effects of interactions of shear with transverse diffusion resulting in enhanced longitudinal disper...
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Published in | Combustion theory and modelling Vol. 24; no. 6; pp. 1054 - 1069 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Abingdon
Taylor & Francis
01.11.2020
Taylor & Francis Ltd |
Subjects | |
Online Access | Get full text |
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Summary: | An analysis is presented for the Burke-Schumann flame established when a fuel tank discharges with mean velocity U along a circular duct of radius a filled initially with air. Attention is focused on effects of interactions of shear with transverse diffusion resulting in enhanced longitudinal dispersion. The analysis accounts for preferential-diffusion effects arising for non-unity values of the fuel Lewis number
, with the Peclet number
based on the thermal diffusivity
taken to be of order unity for generality. The solution to the associated Taylor-dispersion problem is described for times
much larger than the characteristic diffusion time across the pipe
, when the flame is embedded in a mixing region of increasing longitudinal extent moving with the mean velocity. At leading order in the limit
, the longitudinal flame location, the burning rate, and the peak temperature are found to be a function of the effective Lewis number
, whose value changes from
for
to
for
. As a result of this variation, the flame exhibits preferential-diffusion effects that depend fundamentally on
, with important implications in designs of microcombustion devices employing narrow channels and pipes. |
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ISSN: | 1364-7830 1741-3559 |
DOI: | 10.1080/13647830.2020.1813335 |