Characterisation of Balcony Spill Plume Entrainment using Physical Scale Modelling

Abstract

Smoke management design for buildings such as atria and multi-level complexes often requires consideration of smoke produced from a balcony spill plume. This work provides new experimental data to characterise entrainment of air into a balcony spill plume using the approach of physical scale modelling. For a balcony spill plume without entrainment of air into the ends, this work has demonstrated that existing simplified design formulae generally apply for plumes generated from a range of fire compartment geometries. A further simplified design formula is proposed for this type of plume. For a balcony spill plume with entrainment of air into the free ends, the rate of entrainment appears to be specifically dependent on the characteristics of the layer flow below the balcony edge. A simplified design formula is proposed by developing a general empirical expression to describe entrainment of air into the ends of the plume. This work goes some way to explain and reconcile differences in entrainment reported between previous studies and provides improved guidance to designers of smoke management systems.