Fire Safety Science Digital Archive

This work looks at the longitudinal ventilation of fires in a tunnel and the associated phenomenon of backlayer formation. Computational fluid Dynamics are used to simulate the flow and to give predictions that can be compared with experimental data. Focusing in upon the use of Richardson number, different reference temperatures are investigated and it is found that using a temperature calculated directly from the heat release rate of the fire will yield the most useful results. Experimental results are compared to the numerical prediction showing a reasonable level of agreement. The use of a volumetric heat source to model the fire is also validated. That accuracy of the results depends heavily on heat transfer to the wall and roof, is evidenced. Finally, the basic requirement of any scale experiment being that its results are transferable to real-world case it is trying to represent, the existence of a Super Critical Ventilation Velocity of ? 3 ms-1, independent of the power of the fire, above which all the smokes produced are pushed downstream, is verified.