SMOKE MOVEMENT DRIVEN BY A FIRE UNDER A CEILING

This experimental study shows that the near-field ceiling flow above m ost fires comprises a succession of very large, distinct and rapidly r otating smoke rolls or vortices. The sense of rotation in these smoke rolls is always the same and the angular velocities are so large that there is a back-flow (towards the fire) in the lower part of each roll . These large-scale structures nominate variations in velocity and tem perature and, for this reason, it is important to recognise their char acteristics when measuring or modelling fire-driven ceiling flows. Thr ee contrasting model fires have been studied: a pan of flammable liqui d, a flaming wood crib, and a smouldering wood crib. Copyright (C) 199 6 Elsevier Science Ltd.