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M. Mann, Ch. Segalla, E. Pucher:
"CFD-Simulation of Smoke Propagation and Ventilation Efficiency of Tunnel Fire Incidents";
Talk: Tunnel Safety and Ventilation - New Developments in Tunnel Safety, Graz; 2002-04-08 - 2002-04-10; in: "VKM-THD Mitteilungen Volume 80", (2002), ISBN: 3-901351-57-4.

The objective of this project was the development of a prediction method for the propagation of smoke and the temperature distribution in a tunnel during a fire incident. The goal was to generate deeper understanding of the flow phenomena during a tunnel fire and to provide con-structors with an instrument to support ventilation design.
The 3D-simulations were carried out using a commercial CFD-software to benefit from well established programs and models. For special physical phenomena, like soot-radiation interac-tion, special models were implemented. A large number of calculations was performed to in-vestigate grid resolution sensitivity, influence of turbulence models and different approaches of modeling the fire.
During the investigations three main points turned out to have predominant impact on the quality of simulation results: the modeling of the fire by means of heat and volumetric source, gas and soot radiation and boundary treatment at the tunnel walls.
In order to limit computer effort the fire was substituted by an energy source for the required heat release and a mass source which produced the combustion products. The correct smoke quantity and composition were of crucial importance because they are directly related to con-vective and radiative heat transfer. The combustion products (largely carbon dioxide and wa-ter vapor as well as soot particles) are optically dense, which implies that there is a strong interaction with the radiation emitted from the fire. In order to correctly regard these effects an improved version of the `Weighted Sum of Grey Gases Model’ (WSGGM) was imple-mented, which combines the effect on absorption coefficient by gaseous and soot compo-nents.
Test results from the Memorial Tunnel Project were used to verify the newly developed methods and showed remarkable improvement over previous simulation runs omitting the mentioned radiation effects.

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC04404877