Flame propagation across an obstacle: OH-PLIF and 2-D simulations with detailed chemistry
Abstract
Flame propagation across a single obstacle inside a closed square channel is studied experimentally and numerically using a stoichiometric H_2/O_2 mixture at initial conditions 15 kPa and 300 K. The 50% blockage obstacle consists of a pair of fence-type obstacles mounted on the top and bottom walls of the channel. Direct optical visualization was performed using single-image measurement of the planar laser-induced fluorescence of the OH radical (OH-PLIF) and simultaneous high-speed schlieren video to study the flame topology and the flame tip velocity along the channel streamwise axis, respectively. The OH-PLIF images provide a novel level of detail and permit a thorough evaluation of the simulation accuracy. The flame tip accelerates to a peak velocity of 590 m/s just downstream of the obstacle followed by a deceleration and subsequent re-acceleration. The unburnt gas flow ahead of the flame is subsonic at all times. The flame does not show any signs of diffusive-thermal instability. Vortex–flame interactions in the recirculation zones downstream of the obstacle wrinkle the flame. The numerical simulations, based on solving the 2-D compressible reactive Navier–Stokes equations with detailed chemistry, predict the flame tip velocity accurately. However, differences in flame topology are observed, specifically, wrinkling is over-estimated. The over-prediction of flame wrinkling suggests a lower dissipation rate in the numerical simulations than in reality, which could be a consequence of neglecting the third channel dimension. Conditional means of the fuel consumption rate are similar to the consumption rates of 1-D unstretched laminar flames at all times. The increase in pressure during flame propagation causes an increase in fuel consumption rate which needs to be accounted for in simplified modeling approaches.
Additional Information
© 2016 The Combustion Institute. Published by Elsevier Inc. Received 3 December 2015; accepted 11 June 2016. The authors are grateful to the National Research Council Canada for the loan of the intensified camera and UV lens, to Dr. Matthew Johnson from Carleton University for the loan of the lasers and optics, and to Adam Steinberg for the loan of the OH narrow band filter. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant number ACI-1053575 , and J. Melguizo-Gavilanes was supported by NSERC Postdoctoral Fellowship Program.Attached Files
Supplemental Material - mmc1.pdf
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Additional details
- Eprint ID
- 68823
- Resolver ID
- CaltechAUTHORS:20160705-083923958
- ACI-1053575
- NSF
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Created
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2016-07-06Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field