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- Holmstedt, Göran, et al.
(författare)
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Determination of uncertainty of different CFD codes by means of comparison with experimental fire scenarios
- 2009
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Ingår i: Conference Proceedings - Fire and Materials 2009, 11th International Conference and Exhibition.
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Konferensbidrag (refereegranskat)abstract
- This article will summarise the evaluation of four CFD software codes (CFX, FDS4, SMAFS and SOFIE). Evaluation was performed by means of comparing the simulation data with experimental scenarios. The scenarios were chosen to represent scenarios frequently assessed using fire safety design based on performance. The greatest difficulty during validation of CFD-codes is to find well documented relevant experiments. It is true that many large scale experiments including smoke spread have been published but many of them are not described sufficiently and are therefore impossible to use for validation. It is very unusual that data on reproducibility and repeatability is available. After an extensive discussion between the participants in the project five scenarios were chosen. Scenarios 1A (large room with vents), and scenarios 1B1 and 1B2 (corridor with vents) were well documented experiments (repeatability) with ceiling vents and ceiling jets performed earlier at SP in Boras. Scenario 2 is a tunnel fire taken from an experimental study in Boston, US. Scenario 3 is an atrium fire taken from an experimental study in Japan. Lack of well documented fires in retail premises lead us to perform a series of tests in 1/2 scale, 4.1 and 4.2 at SP in Boras. Scenario 5 is an experimental study from Australia including smoke spread from a fire room to an adjacent corridor and a room. The conditions for the simulations included information about the scenarios given above. No information about experimental results was available until the results from the simulations had been sent in to the project manager. The intention was to imitate the working conditions for a consultant as far as possible when using a CFD-simulation to estimate fire safety. In this manner the simulations are dependent on many factors such as the CFD-code used, judgement of input data of the scenarios done by the operator, operator skill etc. The results from the evaluation of the CFD codes showed that the simulation results generally were a good description of the experimental fires studied, but that limitations and specific properties of the different codes, together with the operator factor, can strongly influence the results. The detailed results of all comparisons are given in the final report of the project. It was not possible to include these detailed evaluations in this conference paper but these results are available in the main report as well as in future scientific articles.
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- Holmstedt, Göran, et al.
(författare)
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Validation of CFD codes
- 2008
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Use of CFD (computional fluid dynamics) softwarepackages within fire performance based engineeringand risk assessment is increasing substantially.An important part in the process is thequality assurance. For this reason the SwedishRescue Services Agency (SRV) sponsored aunique research project. Within the project differentcodes for smoke spread and evacuationhave been evaluated. This poster will focus onthe evaluation of four CFD software codes.
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- Ingason, Haukur, et al.
(författare)
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The Metro Project : Final report
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report compiles the results from the METRO project. The different parts of theproject – design fires, evacuation, integrated fire control, smoke control, extraordinarystrain onconstructions and fire- and rescue operations – are presented separately.The most complicated and expensive part of the project was the performance of thelarge scale fire and explosion tests in the Brunsberg tunnel, where the maximum heatrelease rates measured from the metro wagon was 77 MW.The main results from the project are new recommendations regarding design firesin mass transport systems, identification of key factors for fire and smoke spread in tunnelsand at stations as well as regarding the difficulties for disabled persons to evacuatefrom trains in tunnels, new recommended types of way guiding systems, safer design incase of explosions in trains and evaluation of the fire and rescue services’ possibilitiesand limitations in underground mass transport systems.
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- Ingason, Haukur, et al.
(författare)
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The Metro Project: Final Report
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The report compiles the results from the METRO-project. The different parts of the project; design fires, evacuation, integrated fire control, smoke control, extraordinary strain on constructions and fire- and rescue operations are presented separately. The most complicated and expensive part of the project was the performance of the large scale fire and explosion tests in the Brunsberg tunnel. The maximum heat release rates measured from the metro carriage was 77 MW. The maximum ceiling gas temperatures was 1118 °C. These values are high, and should be put into a perspective of the situation and the type of carriages used. The project is not recommending the highest values as the design fire, but values reflected in conditions. The egress study confirm that one of the major issues related to fire evacuation in underground transportation systems is that people often are reluctant to initiate an evacuation. New data show that participants moved with an average of 0.9 meters per second in the smoke filled environment (average visibility of 1.5–3.5 meters). A way-finding installation at the emergency exit, which consisted of a loudspeaker, was found to perform particularly well in terms of attracting people to the door. Two smoke control systems were simulated for a single exit metro station. The systems consisted of a pressurizing supply air system and mechanical exhaust ventilation system with and without platform screen doors. The results show that both the pressurizing supply air system and the mechanical exhaust air system provide effective smoke control for one exit metro station. The significance of the platform screen doors was shown to be important in relation to smoke control. Experiments and simulations have provided increased confidence in ability to simulate explosion scenarios to determine the pressure inside and outside a carriage and to be able to study variations of conditions such as carriage geometry and window designs. The explosion test performed show that an explosion with a relatively minor charge can significantly change the conditions for both evacuees and the rescue service. The results show that the conditions for evacuation and rescue operations can change dramatically as a result of a relatively minor explosion. Evaluation of methods and fire and rescue tactics in metros is given. Mapping of IR imaging as a tactical resource at tunnel fires was presented.
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- Nyman, Hans, et al.
(författare)
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Metro – WP4 : CFD-simulations of a single exit underground station
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report summarises the work of WP4, a part of the METRO project. It investigates theperformance of various smoke control systems for use in underground stations having only one exit to ground level. Two different smoke control systems with two different configurations were investigated: A pressurizing (positive pressure) supply air system; a pressurizing supply air system with platform screen doors; a mechanical exhaust air system with extraction fittings above the track area; and a mechanical exhaust air system with platform screen doors. Simulations were performed using Fire Dynamics Simulator, investigating two different heat release rates – 20 MW and 60 MW.The results show that both the pressurizing supply air system and the mechanical exhaust air system provide effective smoke control. The advantages of a positive pressure supply air system are a relatively simple installation and a lower requisite flow capacity of the fans. The disadvantage is that the smoke is not dispelled, but can be spread to other platforms of the station and even to the next station. The advantages of a mecha- nical exhaust system are that the hot smoke is removed, and that the spread of smoke is restricted to the platform directly exposed to the fire. Disadvantages include the needfor a duct system, which requires space, and considerably higher fan capacities.
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