Ceiling Jet-Driven Wall Flows in Compartment Fires

摘要

Analytic estimates are developed for the early depth of penetration of and the lateral entrainment into negatively buoyant, ceiling jet-driven wall flows which are generic to compartment fire scenarios. When walls are not too far from the fire source, of the order of the fire-to-ceiling distance, it is found that the penetration of the downward flow near such walls is a large fraction of the fire-to-ceiling distance itself, and that this fraction is relatively independent of the details of fire size, spacings, etc. Also, net rate of entrainment into the wall flow as it is buoyed back upward to the ceiling elevation is found to be several times larger than the flow rate of the driving ceiling jet flow immediately upstream of ceiling jet - wall impingement.