Fine bubble modelling of smoke flows.pdf

Fire Safety Journal 38 (2003) 285–298 Short Communication Fine bubble modelling of smoke flows Yuguo Lia,*, Vicent C.W. Shinga, Zhengdong Chenb aDepartment of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong bCSIRO Manufacturing Infrastructure Technology, P.O. Box 56, Highett, Vic. 3190, Australia Received 18 July 2002; received in revised form 7 October 2002; accepted 12 November 2002 Abstract This short note presents a simple experimental modelling technique for smoke spread and movement in enclosures and sloping tunnels by using fine hydrogen bubbles, which are generated by electrolysis in a water tank. Results obtained from two independent experiments agree very well with each other, demonstrating the consistency of the new experimental method. The experimental results for the stratification interface height are also in good agreement with both the experimental data and theoretical predictions available in the literature. The developed method is then used to study smoke spread in a tunnel fire, and the effect of tunnel slopes on smoke movement is visualised. r 2002 Elsevier Science Ltd. All rights reserved. Keywords: Experimental method; Smoke movement; Fine bubble technique; Thermal plumes; Sloping tunnel 1. Introduction There have been significant research efforts in developing design methods for predicting and controlling smoke movement in enclosures and tunnels, e.g. [1,2,15]. The driving force for smoke flow within a building include buoyancy of a rising smoke plume, stack effect, wind pressure and any mechanical fans if exist. Existing experimental modelling method for smoke movement include full-scale real fire method and small-scale laboratory modelling techniques [3–5], all of which have their own merits as well as disadvantages [6]. It is still desirable to have a simple, economical and compact smoke flow modelling system. *Corresponding author. fax: +852 2858 5415. E-mail address: liyg@hku.hk (Y. Li). 0379-7112/03/$ - see