Smoke Venting Effect When Discharging a Solid-cone Water Spray

Abstract

Possible venting of smoke in a room fire while discharging a solid-cone water spray was studied.  The water spray would act at the smoke layer at positions away from the burning object.  In this way, water droplets would not reach the fire plume and affect the combustion directly.  The spray dimension was assumed to be relatively small in comparing with the compartment.  It is observed that operating the solid-cone water spray would give smoke venting effect.  The compartment can be divided into three quasi-steady regions: an upper smoke layer, a lower air layer and a one-dimensional spray.  Fire environment under different spray characteristics was investigated by applying a two-layer zone model developed earlier with some modifications.  Results indicated that the fire environment would be affected significantly by the solid-cone water spray through hot gas entrainment and water evaporation.  The smoke layer interface height would move up with the smoke layer temperature and the flow rate to adjacent space decreased.  Predicted results agree with experimental observations in the small burning test.