Citation

Thomas PH. Fire Safety J. 1987; 12(3): 191-203.

Copyright

(Copyright © 1987, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The data of Morgan and his co-workers for the movement of smoke in 1/10 scale shopping malls are re-examined. This has been done to see how far a simple theoretical treatment based on plume theory and virtual sources (a basis for many calculation methods) can be exploited instead of the more complicated theory of sources of finite sizes. The work follows and extends the work of Law.A number of theoretical relationships are used to correlate data and, in particular, they confirm Law's view that the data can be used to give plausible values for the positions of the virtual sources. Some of the complexities of the theory for finite strip sources may be bypassed if experiments are used for estimating the position of effective virtual sources. Experiments to locate the effective virtual source and the limiting asymptotic form of the theory (appropriate to line sources) can correlate and scale data to an accuracy satisfactory for fire engineering purposes. Various aspects of theory are discussed including the method of allowing for the 'ends' of finite strip sources, and the use of the theory of weak plumes for strong plumes.There remains however a problem in reconciling the 'near' field of the plume rising around the balcony edge to the 'far field', but it is shown that the introduction of an exceptionally high local entrainment could -- for these data -- be avoided if: (a) the mass at any level in the plume is about 45% larger than expected from other laboratory experiments on plumes; or (b) there is extra entrainment due to the deflection and consequent disturbance as the plume strikes the ceiling; or (c) there is extra upward flow owing to radiation heating up the lower walls and floor as suggested by recent investigations. These matters await further investigation.