Modeling and Simulation of Fires in Vehicle Tunnels (original) (raw)
Numerical Study of Smoke Flow Control in Tunnel Fires Using Ventilation Systems
With the aim of evaluating capabilities of a tunnel ventilation system to control the spread of smoke in the emergency operating mode, thereby providing conditions for safe evacuation of people from a fire-struck area, a CFD (Computational Fluid Dynamics) simulation of a fire in a doubletube tunnel was done. By the use of experimental results regarding the combustion dynamics of a passenger car, that is truck on fire and ventilation system operating modes determined according to PIRAC recommendations, a check of critical air velocity required to prevent smoke penetration into the evacuation hallways was performed, as well as the check of the optimum number and positions of ventilators in the tunnel tubes.
CERBERUS: A new model to estimate size and spread for fires in tunnels with longitudinal ventilation
Proc. Int. Conf. on Tunnel Safety and Ventilation–New Developments in Tunnel Safety, Graz, Austria
A new fire model is presented. This model, CERBERUS, combines the results and findings of three previous research projects carried out at Heriot-Watt University. Each of the three projects is briefly described. Combining the results of these three projects, together with knowledge of fire behaviour in the open air, enables the estimation of the maximum fire size of a fire in a tunnel and the conditions under which it might spread to an adjacent vehicle, for a given longitudinal ventilation velocity. To enable these results to be easily used by a wide audience, they are being combined in a single, user-friendly, computer model. The current version of this model (a1.0) is limited to considering fire spread between HGV objects in a single lane tunnel, dimensions based on the Channel Tunnel rail link (UK/France). Future versions of the model will allow for different types of fire and different sizes of tunnel to be considered. Some preliminary results are presented and discussed.
Assessment of Vehicle Fire Development in Road Tunnels for Smoke Control Ventilation Design
2009
A fire in road tunnel can be dangerous and lead to serious consequences if not addressed appropriately. In a tunnel fire incident, creating a smoke free path for motorist evacuation and facilitating fire fighters to access the fire is critical for fire and rescue operations. A means of achieving this is to use ventilation fans to blow sufficient air down the tunnel ensuring no back-layering of smoke occurs upstream of the fire. The airflow necessary for such operation is known as the critical velocity which is a function of a number of factors includes; heat release rate, tunnel geometry, tunnel gradient etc. Among these parameters, the heat release rate is the most difficult to identify as this value is dependent on the types of vehicles, number of vehicles involved, the type of cargo and the quantity of cargo carried by these vehicles. There are also other factors such as the influence of ventilation condition, tunnel geometry and the use of legislation (to restrict hazardous vehi...
Cogent Engineering
The paper shows the findings of fire simulation for various types of vehicles located in different longitudinal positions within a road tunnel. This is an issue that researchers have little investigated over time and so very few studies are available in the literature. The corresponding environmental conditions (expressed in terms of temperature, radiant heat flux, visibility, and CO concentration) along the people evacuation path are also presented, while the associated safety conditions with and without emergency exits are estimated. Computational Fluid Dynamic (CFD) modelling showed for the burning vehicle, which was located half way along the tunnel, higher temperatures compared to the position at one-fourth of the tunnel length (L). However, the environmental conditions along the escape route were found to be worse when the fire source was at 1/4 L compared to that at 1/2 L, since the evacuation time was higher due to the longer Ciro Caliendo ABOUT THE AUTHORS Ciro Caliendo is a full professor of "Roads, railways and airports." His interests include road and tunnel safety; risk analysis, traffic microsimulation, and structural behaviour of infrastructure pavements. He is the author of over 100 papers published in journals and conferences. Paolo Ciambelli is a professor emeritus of "Chemical engineering", CEO of NARRANDO startup. His interests are catalytic materials and processes for industry, energy, and environment, safety in road tunnels. He is the author of 350 articles and 12 patents. Maria Luisa De Guglielmo, is a Ph.D. and research assistant. Her interest deals with road and tunnel safety, and risk analysis. She is the author of over 20 publications. Maria Grazia Meo, is a Ph.D. and post-doc, has experience in CFD fire simulation and people evacuation. She is the author of five publications (Scopus). Paola Russo is an associate professor of "Process & Product Safety in the Chemical Industry." She has expertise in CFD modelling, experimental analysis of gas and explosions, and mitigation and protection systems for industrial equipment. She is the author of 96 publications (Scopus).
Application of CFD techniques for modelling fire tests in road tunnels
This paper provides findings for a project evaluating the effectiveness of current emergency ventilation strategies to control smoke spread in the event of a fire in road tunnels. The research included numerical and experimental phases. The numerical phase used computational fluid dynamics (CFD) models to study smoke ventilation in tunnels. The experimental phase was used to calibrate and to partially validate the chosen CFD models and provide the necessary initial and boundary conditions. Solvent, a CFD model, was used to model two ventilation scenarios using existing data. The paper presents the efforts to validate the CFD model against onsite fire test measurements conducted in a 1.8 km road tunnel. Ce document présente les constatations découlant d'un projet actuel d'évaluation de l'efficacité des stratégies de ventilation de secours dans le contrôle de la propagation de la fumée des incendies de tunnels routiers. Notre recherche comptait une phase numérique et une p...
Tunnelling and Underground Space Technology, 2013
This paper presents findings obtained by CFD modelling for simulating the effects of fire due to different vehicle types in a bi-directional road tunnel. Four different burning vehicles placed in the centre of the driving lane at tunnel middle length were considered. Peaks of the heat release rate (HRR) of: 8, 30, 50, and 100 MW were simulated for the two cars, the bus, the heavy goods vehicle (HGV), and the petrol tanker, respectively. The fire effects on tunnel structure and on environmental conditions along people evacuation path were especially evaluated. The effects of the traffic jam, in contrast with the isolated vehicles, on temperatures, radiant heat flux, visibility distance, and toxic gases concentrations, were also investigated. The worst scenario was identified to be that pertaining to the petrol tanker and more critical conditions were also found when the tunnel was full of vehicles. The maximum gas temperatures reached in the presence of traffic at the side wall (and at the tunnel ceiling reported in brackets) were found to be: 360°C (170°C) for the two cars; 740°C (465°C) for the bus; 835°C (735°C) for the HGV and 1305°C (1145°C) for the petrol tanker, respectively. The presence of the traffic, in contrast with the isolated vehicle, involved an increase in the maximum temperatures equal to 16-17% for the two cars, and contained in the range 12-29% with percentages increasing starting from the tanker, to the HGV and to the bus. In other words when the maximum temperatures produced by the isolated vehicle are very high (e.g. for the tanker), the presence of the traffic had a minor effect. With reference to environmental conditions along the evacuation path, the results showed that in the case of petrol tanker fire the emergency ventilation ensures a tenable level of temperature, radiant heat flux, and toxic gases concentrations up to 5 min from the fire starting. This time increases up to 6.5 min for the HGV and 8 min for the bus. This means that the tunnel users in order to be safe in all scenarios should leave the tunnel within 5 min after the fire starting. Toxic gases concentrations, however, were found to be below the limit values in all cases and also in the presence of traffic. In the light of the aforementioned results, tunnel occupants should be promptly informed of the fire risk and guided to the exit portals. This might be done by equipping the tunnel with illuminated emergency signs located along the tunnel length and by installing traffic lights before the entrances so that the tunnel can be closed in case of emergency. By activating the traffic lights at the portals and the emergency signs (more especially those at the ceiling) at the same time as the emergency ventilation is activated, safer conditions for the people evacuation are expected.
Journal of Combustion, 2017
When a fire occurs in a tunnel in the absence of sufficient air supply, large quantities of smoke are generated, filling the vehicles and any space available around them. Hot gases and smoke produced by fire form layers flowing towards extremities of the tunnel which may interfere with person’s evacuation and firefighter’s intervention. This paper carries out a numerical simulation of an unexpected fire occurring in a one-way tunnel in order to investigate for the critical velocity of the ventilation airflow; this one is defined as the minimum velocity able to maintain the combustion products in the downstream side of tunnel. The computation is performed successively with two types of fuels representing a large and a small heat release rate, owing to an open source CFD code called ISIS, which is specific to fires in confined and nonconfined environments. It is indicated that, after several computations of full-scale fires of 43.103 and 19.103 kJ/kg as heat release rate, the velociti...
Unsteady 2-Dimension Computational Modeling of Accidental Firing in Tunnels
Journal of Engineering and Development, 2006
All tunnels require ventilation to maintain acceptable levels of contaminants produced by vehicle engines during normal traffic operation (normal ventilation), and to remove and control smoke and hot gases during a fire emergency (emergency ventilation) ref. (7). To protect passengers, personal and equipment in a tunnel fire, it is important to understand and predict the temperature distribution through the tunnel during the tunnel fire. In this paper, a computer program (Tunnel) has been built to investigate the temperature profile along the tunnel for passenger car and three passenger cars with and without ventilation by using (explicit F.D) method . In this paper, also we will study the effect of the system ventilation on the temperature profile and estimate the required time to return temperature to ambient value for passenger car and three passenger cars
Tunnelling and Underground Space Technology, 2016
This paper uses Fire Dynamics Simulator (FDS) to study various arrangements of different vehicles at upstream of two fire sources. In order to make a comprehensive study, the effects of two fire sources in both lateral and longitudinal directions are investigated. The results reveal that the behavior of two fire sources, in both perpendicular directions, is directly influenced by distance between them. For small vehicles, variations of the arrangement and distance between the vehicles and fire sources do not affect the calculated Critical Ventilation Velocity (CVV). However, the presence of medium vehicles strengthens the influence of inertia force rather than buoyant force of fire plume in the tunnel. Accordingly, when there is a short distance between fires and medium obstructions, less air ventilation is needed to prevent smoke back-layering. Eventually, far distance between the vehicles and the fires results in vanishing obstruction effects. Consequently, CVV is the same as the case in which there is no vehicle in the tunnel.