doi:10.3850/978-981-08-7724-8_10-03

ABSTRACT

In order to study basic features of the venting explosion process accompanied by a second pressure peak that evolves during the venting period after vent cover rupture under simplified conditions, flame behaviours and pressure variations were examined in detail for a small cubic explosion vessel filled with a uniform quiescent propane-air mixture. Evolution of the second pressure peak occurs only for a limited composition range of rich mixtures coupled with appropriate ignition locations. Flame front instabilities, producing fine-scale regularly spaced wrinkles or stripes on the flame front, starts with fine oscillations after the rupture, where the stripes are mostly initiated from grooves existing prior to the rupture. The development of the instabilities leads to cellular structures producing intense combustion toward the second pressure peak. The different aspects of instabilities strongly depend on the equivalence ratio, as well as ignition location. 0scillations of the flame front normal to the locally averaged flame surface is linked to the acoustic oscillation in the vessel and play an important roles for flame front instabilities, involving Rayleigh-Taylor instability and preferential diffusion in rich propane-air flames.

Keywords: Second pressure peak, Flame front instabilities, Fine structure.

© 2011 CPD Unit, University of Leeds