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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 44747 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Farhanieh, Bijan
- Abstract:
- Fire events and the related toxicants such as CO are responsible for many fatalities inthe current century. These hazardous events are more dangerous when they occur in enclosedspaces. In the present study, a theoretical relation is developed for horizontal distribution of COin a large tunnel fire. Then, developed criterion is used to study the effect of rudimentaryparameters such as Heat Release Rate (HRR) of fire and tunnel Aspect Ratio (AR) on CO andtemperature stratification. Theoretical results of various heat release rates and aspect ratios forhorizontal distribution of CO are compared with numerical results using Fire DynamicsSimulator (FDS5.5). It is found that big fires have higher rate of CO concentration decay withrespect to smaller ones due to higher air entrainment to the travelling plume. It is indicated thatthe smoke travelling at higher values of tunnel AR, dilutes faster. Also, the relevant variations oftemperature and CO concentration are discussed for tunnel angles from -20˚ to 20˚ employingFDS5.5. The tunnel blockage ratio is the ratio of obstructed cross-sectional area that is blocking the flow area in the tunnel. Fire incidents due to this have considerable cross-sectional area such as for trains or heavy vehicles. In this article, we numerically investigate the effect of vehicular blockage on CO emission from a fire in a tunnel. FDS5.5 has been used for numerical simulations of a constant ventilation velocity and heat release rate. A huge amount of air entrance to the travelling smoke has been indicated for larger blockage ratios by the means of a longitudinal CO axis beneath the ceiling and a longitudinal velocity axis from ceiling to the floor at various positions. Air Curtain is also employed to see its influence on carbone monoxide distribution
- Keywords:
- Fire Dynamic Simulator (FDS)Software ; Carbone Monoxid Distribusion ; Road Tunnels ; Tempreture Distribution ; Carbon Monoxide Dispersion
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