ISSN Online: 2377-424X
International Heat Transfer Conference 12
Effects of equivalence ratio on combustion in an oscillating-flow porous burner
要約
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.