Effect of fuel soaked time and fuel ratio on the flame spread rate over a porous bed wetted with liquid fuel

• We examined the rate of flame spread over porous bed wetted with liquid fuel.
• The rate of flame spread increases as the fame initiation delay decreases.
• Increasing fuel ratio drops the flame spread rate if bed ignited after some delay.
• Rising fuel ratio increases the rate of flame spread if bed ignited with no delay.
• Size of particles has strong effect on the rate of flame spread.

An experimental investigation was conducted to explore the rate of flame spread over an unconsolidated porous bed of sand wetted with 2-propanol under a range of operating conditions. Video cinematography was employed to determine the rate of flame spread and characterise the combustion behaviour of the system. The rate of flame spread strongly correlated with: (i) the ratio of fuel volume to the weight of the sand bed, referred to as FR, and (ii) the flame initiation delay, referred to as FID. The rates of flame spread associated with no initiation delay cases were found to rise with increasing FR while for cases associated with any given flame initiation delay the rate of flame spread was found to decrease with increasing FR. In addition, the rate of change in flame spread was observed to be different for beds containing finer particles in comparison to those containing coarser ones.