دانلود رایگان مقاله تاثیر سوخت شکل هندسی در پیش بینی شبیه ساز پویایی آتش سوزی

ABSTRACT

This paper uses four different simple geometrical shapes to simulate a large-scale heavy goods vehicle (HGV) tunnel fire experiment using Fire Dynamics Simulator, version 6 (FDS6) in order to investigate the influence of using different fuel package shapes. Simulations also investigate the influence on temperature profiles when a large target is placed downstream of the fuel package. Predictions of flame extension, temperature profiles and gas species concentrations are compared with the experimental data. The use of the geometrical shapes causes significant differences in flame extension lengths during the fully developed fire phase. The variation in temperature predictions caused by using the different fuel shapes are insignificant when a large target is present behind the fire, however this is not the case if the target is omitted especially during the fully developed phase.

5. Conclusions

This work uses four different simplified geometrical shapes in FDS6 to simulate a fuel package that represents a largescale HGV tunnel fire which includes the influence of a forced ventilation system. It is found that flame extension predictions are affected by the use of fuel geometrical shapes when the fire is fully developed. During this phase the predicted values of flame length (25 to 30 m) in scenarios in which vertical as well as horizontal surfaces are burning (3DS and 3DA) are similar to the values calculated from the Ingason et al’s model. The use of the different geometrical shapes only weakly affects the predicted temperature distributions in the presence of the large target located downstream of the fire. However significant differences are obtained during the fully developed phase using the different fuel shapes without the presence of the target. Finally the 2D burner on the top of the fuel package scenario (2DT) results in different predicted gas distribution profiles at location D170 when compared with the three other geometrical scenarios. In summary this case study highlights the influence of using different fuel geometrical shapes on flame extension, temperature distributions and gas species concentrations during different fire development phases. Depending on the objective the results from this work suggest that the use of ‘a 2D gas burner’ in fire engineering simulations using FDS may not always be suitable in cases involving a fuel package that creates a blockage within a tunnel that is subject to a forced ventilation. The work also illustrates the potential importance of including any large target items that are located downstream of the fire.