Sharif Digital Repository

Designing of an efficient emergency ventilation system is one of the main approaches to prevent the perilous fire in tunnel phenomenon. For this purpose, firstly, fire behavior and its heat release rate should be investigated. Knowing about temperature distribution and smoke movement is the second step. One of the most considerable factors in smoke control is critical velocity. It means the minimum velocity to prevent backlayering flow. If longitudinal ventilation velocity were less than this amount, smoke and hot gases originated from the fire can enter the upstream zone. This may cause lack of oxygen and decrease visibility for the passengers when they are escaping from the fire field. In... 

Fire phenomenon and its hazards through urbun transportation systems like subway is a major debate in management of these territories. Recently, varios factors, such as great deal of passengers whom travel by these systems, financial damages and psychological disorders due to fire accidents resulte in noticeable investigation to prevent and reduce these subjects. In this research, simulating of railcar fire has been conducted to estimate the amount of heat release rate (HRR) and parameters which affect on it by modelling behavior of combustible materials inside railcar. As regards to materials which are available inside railcar that participate in fire, their behavior face to heat flux has... 

Based on thecnology development, humans are able to shorten the ways by using tunnels. But beside this big benefit, there are some limitations, both in digging and utilization stages. One of the most important challenges in utilization stage is ventilation. Beside the normal ventilation -which is done to reduce the pollutants like carbon monoxide- a special system must be designed to control the hot and high energy combustion products. This system is named emergency ventilation. In this research, emergency ventilation in long road tunnels, using water curtain is simulated numerically using FDS code, and different parameters are investigated. The fuel source in this research is a pool of... 

Based on thecnology development, humans are able to shorten the ways by using tunnels. But beside this big benefit, there are some limitations, both in digging and utilization stages. One of the most important challenges in utilization stage is ventilation. Beside the normal ventilation -which is done to reduce the pollutants like carbon monoxide- a special system must be designed to control the hot and high energy combustion products. This system is named emergency ventilation. In this research, emergency ventilation in long road tunnels, using water curtain is simulated numerically using FDS code, and different parameters are investigated. The fuel source in this research is a pool of... 

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... 

In this thesis, behavior of multiple pool fires was investigated in the numerical method. Fire modeling is a complex process. The complexity intensify when simultaneous fires occurred, pool fire is the most likely among all kind of fires in city and industrial units. FDS software, a common CFD model for fire simulation, was used to simulate multiple pool fires. Using of CFD models is one of the most advanced techniques to fire simulation and FDS software have been used by engineers and researchers due to using of this technique. In the beginning, review of the existing investigations which FDS performance was examined of fire simulation is presented. Besides of the data gathering, in this... 

Fire spread in a road tunnel and its transmission from one vehicle to another was investigated numerically in this study. FDS was used as an open-source, free CFD software. Two boxes close to the car’s dimensions were modeled in a 40m long tunnel and fire transmission from one to another was considered. Ignition temperature was assigned to the second box’s surface as the condition for its ignition start and longitudinal ventilation was applied to the tunnel. At each case, ignition time of the second box was captured. Effects of ventilation velocity, HRR, distance, tunnel height and slope of the tunnel parameters were considered on the ignition time of the second box. Moreoveras a case study,... 

Fire is the most likely type of process accident which occurs in industrial plants. Among all different types of fire, pool fire is the most frequent one, so there are extensive researches done about pool fire. One of the research areas that has drawn a lot of attention in recent years, is pool fire modeling. Results obtained from fire modeling are quite applicable in different fields of safety engineering such as Quantitative Risk Assessment (QRA) or fire proofing studies of process equipment. But fire modeling is an inherently complex process. Because there are several aspects involved such as multi-phase flow, turbulent mixing, combustion and different mechanisms of heat transfer. This... 

In recent years, due to fires in mines around the world, the need to study the dynamic behavior of fire to understand how it spreads and design an appropriate fire extinguishing system to reduce damage to people and underground facilities has been felt. Mine fires are usually caused by external sources such as cable connections, methane gas explosions, or coal self-ignition due to oxygen uptake and rising temperatures.In this research, using Fire Dynamic Simulator (FDS) software, after drawing the geometry of a coal tunnel corridor in progress and creating a fire model through pyrolysis of PVC, fire extinguishing was performed by nozzles. If the nozzle does not succeed in extinguishing the...