A comparison between channelled and unchannelled balcony spill plumes

Abstract

The use of channelling screens in smoke management design can reduce balcony spill plume entrainment by restricting smoke spread under the balcony. The omission of channelling screens can gave rise to a greater lateral extent resulting in a change in the entrainment conditions. This work provides new experimental data using physical scale modelling to enable a comparison between channelled and unchannelled plumes. The lateral spread for unchannelled plumes was found to be dependent upon the velocity of the flow from the fire compartment opening. The measured entrainment for plumes without screens was greater than that from equivalent plumes with screens and the relative difference in entrainment increased as the width of the fire compartment opening decreased. A simple approximation to predict entrainment for unchannelled plumes from wide fire compartment openings is proposed. Practical application: The ability to determine amount of entrainment from a balcony spill plume is important to fire engineers involved in smoke management design. Whether channelling screens are part of the design will likely affect this entrainment. This article presents a simple approximation that can be used to predict entrainment for unchannelled plumes from wide fire compartment openings building on previous work by Law.