Results are presented from an experimental programme of studies on the influence of water sprays on flame propagation. Two experimental configurations were used with differing length-to-diameter ratios. The present results suggest that the mitigating effect of a water spray is enhanced for flames propagating in vessels with large length-to-diameter ratio. The effectiveness of the sprays is further increased if the flame is subjected to greater acceleration before it is incident on the spray. Evaporation alone is insufficient to account for the resulting flame quenching and the mitigating effect of the spray is attributed to increased heat and mass transfer in the combustion zone as a result of a break-up of the initial spray in the induced flow field ahead of the flame front. The time scales over which quenching is observed are consistent with an existing model for shear-layer induced droplet break-up, but the gasdynamic conditions are such that other break-up mechanisms cannot be discounted.
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