Instabilities in high pressure, iso-octane-air spherical explosion flames

Lockett, R. D., Huang, Y. & Woolley, R. (2014). Instabilities in high pressure, iso-octane-air spherical explosion flames. Paper presented at the 8th International Seminar on Flame Structure, 21-24 Sep 2014, Berlin, Germany.

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Abstract

High speed video shadowgraph and Schlieren images of spherical explosion flames obtained in the Leeds bomb have been analysed in the context of the Bechtold-Matalon linear model of spherical explosion flame instabilities. Analysis of the dispersion relation identifies the peninsula of instability, and the conditions for which the spherical explosion flame is conditionally and/or unconditionally unstable. Histograms of cellular length-scales have been derived, showing the change in cellular length scale with flame Peclet number. Nonlinear effects result in larger wavenumber (small wavelength) cellularity than that predicted by the linear model. Finally, rich 3 bar and 4 bar explosion flames exhibit cellularity with two distinct ranges of wavenumber (wavelength) that may be linked to the Darrius-Landau hydrodynamic instability (small wavenumber instability), and the thermal-diffusive instability (large wavenumber instability).

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Explosion; Flame; Cellularity; Instability
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Divisions: School of Engineering & Mathematical Sciences > Engineering
URI: http://openaccess.city.ac.uk/id/eprint/13541

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