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Li, Y. Z. & Ingason, H. (2018). Discussions on critical velocity and critical Froude number for smoke control in tunnels with longitudinal ventilation. Fire safety journal, 99, 22-26
Open this publication in new window or tab >>Discussions on critical velocity and critical Froude number for smoke control in tunnels with longitudinal ventilation
2018 (English)In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 99, p. 22-26Article in journal (Refereed) Published
Abstract [en]

Determination of critical velocity is a key issue for smoke control in any tunnel with longitudinal ventilation. The critical Froude model using single Froude number of 4.5 has for decades been widely used in engineering applications. This value was originally used by Danziger and Kennedy and they argued that the critical Froude number obtained by Lee et al. was in a range of 4.5 and 6.7 and therefore a conservative value of 4.5 was obtained. This paper explores the validity of using single critical Froude number of 4.5 by investigating the original sources and comparing it to recent research results. It was found that the value of 4.5 obtained in the original source corresponds to a large tunnel fire and it correlates well with data from other literature within a narrow range of large fire sizes. Using this value produces a significantly lower critical velocity for a wide range of fire sizes and therefore it is not conservative. The Froude number of 6.7 obtained by Lee et al. corresponds to another Froude number with a different definition and it is therefore not comparable with the value of 4.5. It is found that the use of a single value of 4.5 for the critical Froude number is not reasonable in calculation of the critical velocity for smoke control in tunnels with longitudinal ventilation.

Keywords
Critical Froude number, Critical velocity, Longitudinal ventilation, Tunnel fire, Fires, Froude number, Longitudinal control, Smoke, Smoke abatement, Velocity, Conservative value, Critical velocities, Engineering applications, Froude modeling, Lower critical, Recent researches, Tunnel fires, Ventilation
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-34305 (URN)10.1016/j.firesaf.2018.06.002 (DOI)2-s2.0-85049337369 (Scopus ID)
Available from: 2018-08-06 Created: 2018-08-06 Last updated: 2018-08-24Bibliographically approved
Li, Y. Z. & Ingason, H. (2018). Influence of fire suppression on combustion products in tunnel fires. Fire safety journal, 97, 96-110
Open this publication in new window or tab >>Influence of fire suppression on combustion products in tunnel fires
2018 (English)In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 97, p. 96-110Article in journal (Refereed) Published
Abstract [en]

A series of model scale tunnel fire tests was carried out to investigate effects of the fire suppression system on production of key combustion products including CO and soot. The key parameters accounted for in the tests include fuel type, ventilation velocity and activation time. The results show that fire suppression indeed has influence on production of combustion products especially for cellulose fuels. In case that the fire is not effectively suppressed, e.g. when the water density is too low or activation is too late, the CO concentration and visibility could be worse than in the free-burn test. From the point of view of production of combustion products, only fire suppression systems with sufficient capability and early activation are recommended to be used in tunnels.

Keywords
Activation, CO yield, FED, Fire suppression, Soot yield, Tunnel fire, Ventilation, Visibility, Chemical activation, Combustion, Fire extinguishers, Flammability testing, Soot, CO concentrations, Combustion products, Fire suppression systems, Investigate effects, Model scale tunnels, Tunnel fires, Ventilation velocity, Fires
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-31173 (URN)10.1016/j.firesaf.2017.06.011 (DOI)2-s2.0-85024494074 (Scopus ID)
Available from: 2017-08-23 Created: 2017-08-23 Last updated: 2018-08-24Bibliographically approved
Li, Y. Z., Ingason, H. & Jiang, L. (2018). Influence of tunnel slope on smoke control.
Open this publication in new window or tab >>Influence of tunnel slope on smoke control
2018 (English)Report (Other academic)
Abstract [en]

The critical velocity and backlayering length in sloped tunnels are investigated by numerical simulations using FDS. Simulation in two full-scale tunnels, with negative slopes ranging up to -18 % and heat release rates from 5 to 100 MW were carried out.

The results show that NFPA 502 equation significantly overestimates the effect of negative slopes.

The equation proposed by Atkinson and Wu is found to be in closer agreement with the results. A simplified correlation, i.e. Eq. (12), is proposed and recommended for practical use.

The previous correlation for dimensionless backlayering length, Eq. (3), is valid for tunnels of various slopes and aspect ratios, and can be used for prediction of backlayering length.

Publisher
p. 22
Series
RISE Rapport ; 2018:50
Keywords
critical velocity, tunnels, sloped tunnel, FDS
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36626 (URN)978-91-88695-92-5 (ISBN)
Available from: 2018-12-14 Created: 2018-12-14 Last updated: 2018-12-14Bibliographically approved
Ingason, H. & Gehandler, J. (2018). Metoder för att testa dukar och membran i tunnlar och bergrum.
Open this publication in new window or tab >>Metoder för att testa dukar och membran i tunnlar och bergrum
2018 (Swedish)Report (Other academic)
Alternative title[en]
Test methods for tunnel linings
Abstract [en]

Tunnel and rock lining systems are used for drainage and icing protection. These systems can consist of any combination of concrete, metal, plastic or textile. The report summaries the available methods, both for testing and for installation. The large variation in both systems and test methods often make it difficult for constructors or designer to understand the importance of different methods. The report gives indication of what type of linings exists and how to ensure the fire safety of such systems. Fire safety properties can be verified in three different ways: #1 Full systems can be tested in full scale fire tests, #2 a section of the system can be tested in standardized furnace tests, or #3 plastic and/or textile membrane can be tested with regards to requirements on fire spread. It is suggested to require that a fire should not be able to propagate in the system. This can be verified with #3 above requiring class B, C or D according to EN 13501-1. If the lining system offers structural fire protection, it can be verified suing #2 above.

Publisher
p. 19
Series
RISE Rapport ; 2018:54
Keywords
tunnel linings, fire, test methods
National Category
Other Civil Engineering
Identifiers
urn:nbn:se:ri:diva-36549 (URN)978-91-88695-98-7 (ISBN)
Note

Denna sammanställning har genomförts inom ramen för TUSC Tunnel and Underground Safety Center. Medverkande organisationer är RISE Research Institutes of Sweden (tidigare SP Sveriges tekniska forskningsinstitut), Trafikverket, Fortifikationsverket och SKB Svensk kärnbränslehantering. Rapporten sammanställer olika brandprovningsmetoder och ger förslag till provningsmetodik för tunnelduk.

Available from: 2018-11-29 Created: 2018-11-29 Last updated: 2018-12-03Bibliographically approved
Li, Y. Z. & Ingason, H. (2018). Overview of research on fire safety in underground road and railway tunnels. Tunnelling and Underground Space Technology, 81, 568-589
Open this publication in new window or tab >>Overview of research on fire safety in underground road and railway tunnels
2018 (English)In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 81, p. 568-589Article in journal (Refereed) Published
Abstract [en]

In the past two decades, the interest in fire safety science of tunnels has significantly increased, mainly due to the rapidly increasing number of tunnels built and the catastrophic tunnel fire incidents occurred. This paper presents an overview of research on fire safety in underground road and railway tunnels from the perspectives of fire safety design. The main focuses are on design fires, structural protection, smoke control and use of water-based fire suppression systems. Besides, some key fire characteristics, including flame length, fire spread, heat flux and smoke stratification, are discussed.

Keywords
Design fire, Fire characteristics, Fire safety, Fire suppression, Railway tunnel, Road tunnel, Smoke control, Structural protection, Underground tunnel, Fire protection, Fires, Heat flux, Railroads, Roads and streets, Smoke, Smoke abatement, Tunnels, Design fires, Railway tunnels, Underground tunnels, Railroad tunnels, control system, fire management, railway, road, safety, tunnel design
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35588 (URN)10.1016/j.tust.2018.08.013 (DOI)2-s2.0-85052484757 (Scopus ID)
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06Bibliographically approved
Gehandler, J. & Ingason, H. (2018). Principer och strategier för ventilation vid brand i undermarksanläggningar.
Open this publication in new window or tab >>Principer och strategier för ventilation vid brand i undermarksanläggningar
2018 (Swedish)Report (Other academic)
Abstract [en]

The report describes different underground systems including mines and tunnels during construction (tunneling). The key factors that affect fire development in underground systems are described. Proposal and recommendations for ventilation strategies in case of fire are given. The report covers both fuel- and ventilation-controlled fires. In general, a minimal ventilation limits the fire growth and may even inert the fire through ascended smoke. A minimal ventilation also contributes to improved conditions for a first fire extinguishing attempt and evacuation.

Publisher
p. 21
Series
RISE Rapport ; 2018:70
Keywords
underground; tunnel; mine; fire; ventilation; evacuation; rescue
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36628 (URN)978-91-88907-14-1 (ISBN)
Available from: 2018-12-14 Created: 2018-12-14 Last updated: 2018-12-14Bibliographically approved
Li, Y. Z. & Ingason, H. (2018). Tunnel fire safety: editorial. Fire safety journal, 97, 85-86
Open this publication in new window or tab >>Tunnel fire safety: editorial
2018 (English)In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 97, p. 85-86Article in journal, Editorial material (Other academic) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-34458 (URN)10.1016/j.firesaf.2018.03.006 (DOI)2-s2.0-85047129878 (Scopus ID)
Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-08-24Bibliographically approved
Li, Y. Z. & Ingason, H. (2017). Analysis of Muskö tunnel fire flows with automatic sprinkler activation. Borås
Open this publication in new window or tab >>Analysis of Muskö tunnel fire flows with automatic sprinkler activation
2017 (English)Report (Other academic)
Abstract [en]

The focus of the present study is analyzing the best position of a sprinkler nozzle in a tunnel cross-section in the Muskö tunnel, south of Stockholm, Sweden. Activation of the sprinklers installed along the centerline and along the sidewall is investigated through analysis of full scale experiments and by three dimensional numerical modelling. Then the tunnel velocity is analyzed by one dimensional numerical modelling for various fire locations in the Muskö tunnel. For both activating the automatic sprinklers nearby the fire and avoiding activation of the sprinklers further downstream, the automatic sprinklers are recommended to be installed along the centerline of the tunnel. It has also been found that the tunnel velocity varies significantly with the fire location. When the fire is on the left side of the tunnel, the flow velocity mostly remains in a range of 1 m/s (positive or negative) within the first 10 minutes, which helps early activation of the automatic sprinklers. When the fire is on the right side of the tunnel, the flow velocity mostly remains within a range of -1 m/s and 1 m/s within the first 5 minutes, and the velocity mostly increases to 2 m/s at around 10 min. Therefore, the scenario for fire located on the left side is better than that for fire on the right side, especially when it is located between the middle of the right section and the right portal. As one typical case with fire on the right side, the tunnel velocity maintains at 1 m/s for the first 5 min and gradually increases to 2 m/s at 10 min. Under such conditions, the automatic sprinkler system is expected to perform well. 

Place, publisher, year, edition, pages
Borås: , 2017. p. 30
Series
RISE Rapport ; 2017:51
Keywords
tunnel fire, tunnel velocity, automatic sprinkler, activation
National Category
Chemical Process Engineering Building Technologies Infrastructure Engineering Transport Systems and Logistics Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:ri:diva-32445 (URN)978-91-88695-16-1 (ISBN)
Funder
Swedish Transport Administration
Note

The research work presented in this report has been sponsored by Tunnel and Underground Safety Center (TUSC) with additional funding from STA (Trafikverket). 

Available from: 2017-11-03 Created: 2017-11-03 Last updated: 2018-08-24Bibliographically approved
Li, Y. Z. (2017). Effect of cross section on critical velocity in longitudinally ventilated tunnel fires. Fire safety journal
Open this publication in new window or tab >>Effect of cross section on critical velocity in longitudinally ventilated tunnel fires
2017 (English)In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226Article in journal (Refereed) In press
Abstract [en]

Numerical and theoretical work was conducted to investigate the effect of tunnel cross section on critical velocityfor smoke control in longitudinally ventilated tunnel fires. The results show that for small fires, the criticalvelocity decreases with both the increasing tunnel height and tunnel width. For large fires, the critical velocitysignificantly increases with the increasing tunnel height but is independent of tunnel width. Differentcalculation models are compared with a focus on effect of tunnel cross section. A new correlation is proposedto account for the effect of tunnel width based on the previous model.

Keywords
Critical velocity, Tunnel fires, Longitudinal ventilation, Smoke control
National Category
Civil Engineering Mechanical Engineering Chemical Sciences
Identifiers
urn:nbn:se:ri:diva-29724 (URN)10.1016/j.firesaf.2017.03.069 (DOI)
Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2018-08-24Bibliographically approved
Fan, C. G., Ji, J., Li, Y. Z., Ingason, H. & Sun, J. H. (2017). Experimental study of sidewall effect on flame characteristics of heptane pool fires with different aspect ratios and orientations in a channel. Proceedings of the Combustion Institute, 36(2), 3121-3129
Open this publication in new window or tab >>Experimental study of sidewall effect on flame characteristics of heptane pool fires with different aspect ratios and orientations in a channel
Show others...
2017 (English)In: Proceedings of the Combustion Institute, ISSN 1540-7489, E-ISSN 1873-2704, Vol. 36, no 2, p. 3121-3129Article in journal (Refereed) Published
Abstract [en]

A series of small scale tests was conducted to investigate the influence of sidewall on flame characteristics of heptane pool fires in a channel, considering pool shape (aspect ratio: 1, 2, 4 and 8) and pool orientation relative to sidewall. Distance between fire and sidewall was changed systematically. Both transverse flame development (along the direction of channel width) and longitudinal flame development (along the direction of channel length) were recorded by digital video. Results show that for a fixed fire location, the heat release rate increases with the increasing pool aspect ratio (namely a larger pool perimeter), which indicates more air entrainment and more intense combustion. In wall fire cases, when the long pool rim is perpendicular with channel sidewall, the flame can obtain more air entrainment with a weaker boundary restriction from the sidewall, compared to the case with the long pool rim being parallel with sidewall. Comparison of some previously established correlations based on various experimental conditions with our test results is made. Due to the fact without considering sidewall effect and fuel shape on the air entrainment of fire plume, the classic correlations need to be further improved. Therefore, an integral flame length model considering both sidewall effect and fuel shape is developed, which correlates well with all the data from cases with various pool positions, orientations and aspect ratios. © 2016 The Combustion Institute. Published by Elsevier Inc.

Keywords
Air entrainment, Flame length, Fuel shape, Pool fire, Sidewall effect, Aspect ratio, Combustion, Computer graphics, Fire protection, Fires, Fuels, Heptane, Lakes, Multimedia systems, Supersonic aerodynamics, Experimental conditions, Flame characteristics, Heat Release Rate (HRR), Heptane pool fires, Pool fires, Sidewall effects, Small-scale tests
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-31128 (URN)10.1016/j.proci.2016.06.196 (DOI)2-s2.0-84978870580 (Scopus ID)
Note

Funding details: 51376173, NSFC, National Natural Science Foundation of China; Funding text: This work was supported by National Natural Science Foundation of China (NSFC) under Grant no. 51376173, National Key Research and Development Plan under Grant no. 2016YFC0800100 and National Top-Notch Young Talents Program. Chuan Gang Fan was also financially supported by the Opening Fund of the State Key Laboratory of Fire Science under Grant no. HZ2016-KF03.

Available from: 2017-08-28 Created: 2017-08-28 Last updated: 2018-08-24Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9340-6768

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