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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Effects of equivalence ratio on combustion in an oscillating-flow porous burner

Get access (open in a dialog) DOI: 10.1615/IHTC12.4800
6 pages

Résumé

An experiment has been carried out to study combustion characteristics of the oscillating flow of a propane/air mixture in a porous burner composed of packed stainless screens. The effects of the equivalence ratio on the movement of the superadiabatic flame front, the length of the flame volume and the flame colour, inside the inert porous burner were investigated. The results show that, after a quasi-steady state was established and a visible flame volume was formed, the flame front was always located near the inlet end. Thus, the flame location oscillated between two ends of the porous medium burner during a cycle. However, no flame was observed in the middle part of the porous medium. At the instant immediately after the flow direction was reversed, there was a short period of time where no-flame existed in the entire porous burner. The time scale of this period was found to be proportional to the volume of the exhausting gas in the duct. The results also show that the length of the flame volume was strongly affected by the equivalence ratio. When the firing rate was kept constant, the length of the flame volume increased with the increase of equivalence ratio. A comparison with a steady flow porous medium burner operating at the same equivalence ratio and the same firing rate shows that the stability limits for stable combustion are improved considerably because of the oscillating motion, and the temperature distribution along the flame volume inside the porous burner is more uniform.