Thermal buoyant smoke back-layering flow length in a longitudinal ventilated tunnel with ceiling extraction at difference distance from heat source

Chen, L.F.; Hu, Longhua; Zhang, Xinglai; Zhang, X.Z.; Zhang, X.C.; Yang, Lizhong

doi:10.1016/j.applthermaleng.2014.12.034

Cited by 89 publications

(33 citation statements)

References 22 publications

(12 reference statements)

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“…One of the basic scientific problems, when a fire occurs in a tunnel, is the specification of the longitudinal ventilation velocity necessary to prevent upstream movement of combustion products. So far, the value of the critical velocity for various tunnels has been obtained mainly from sets of equations derived by applying the Froude number conservation, combined with experimental data [2][3][4][5][6][7][8]. The Froud number is the ratio of inertia forces to gravitational force.…”

Section: Critical Velocitymentioning

confidence: 99%

“…As the influence of the distance between the ceiling opening and heat source on backlayering length had not previously been studied, Chen et al [3] performed a series of experiments in a reduced-scale tunnel to measure the backlayering length in this situation based on [20]. They concluded that the backlayering length increased with the heat source-ceiling extraction (opening) distance.…”

Section: Fire Location Effectmentioning

confidence: 99%

“…They concluded that the backlayering length increased with the heat source-ceiling extraction (opening) distance. Furthermore, a new theoretical model was deducted to predict the backlayering length with the heat source-extraction (opening) distance included [3].…”

Section: Fire Location Effectmentioning

confidence: 99%

See 2 more Smart Citations

Critical Velocity and Backlayering Conditions in Rail Tunnel Fires: State-of-the-Art Review

Haddad

Maluk

Reda

et al. 2019

Journal of Combustion

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The use of interurban and urban trains has become the preferred choice for millions of daily commuters around the world. Despite the huge public investment for train technology and mayor rail infrastructure (e.g., tunnels), train safety is still a subject of concern. The work described herein reviews the state of the art on research related to critical velocity and backlayering conditions in tunnel fires. The review on backlayering conditions includes the effect of blockages, inclination, and the location of the fire source. The review herein focuses on experimental and theoretical research, although it excludes research studies using numerical modeling. Many studies have used scaled tunnel structures for experimental testing; nevertheless, there are various scaling challenges associated with these studies. For example, very little work has been done on flame length, fire source location, and the effect of more than one blockage, and how results on scaled experiments represent the behaviour at real-scale. The review sheds light on the current hazards associated with fires in rail tunnels.

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Section: Critical Velocitymentioning

confidence: 99%

Section: Fire Location Effectmentioning

confidence: 99%

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Critical Velocity and Backlayering Conditions in Rail Tunnel Fires: State-of-the-Art Review

Haddad

Maluk

Reda

et al. 2019

Journal of Combustion

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“…Hydraulic diameter parameter as a variable was chosen to identify different tunnels. (Chen et al, 2015) In this study, the effect parameters, away from the fire source of the tunnel, obstacle before and after the fire, existence are several sources of fire in the tunnel and ventilation shaft between tunnels will discuss on the critical velocity. Each effect parameter according to a correlation analysis of the numerical results and the relationship between dimensionless critical velocity and dimensionless heat release stated.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Critical Velocity in Ventilation

Kesadian¹,

Adamian²

2016

MAS

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Given the importance of the safety and health of passenger's in underground tunnels, analysis and simulation of fires in tunnels is to design a ventilation system. Longitudinal ventilation systems are widely used in tunnel ventilation and are one of the most important parameters for fire safety in this type of critical velocity system. Critical velocity of ventilation is minimum longitudinal velocity flow of air that prevents the smoke from the fire to the upstream flow.In this study, the effects of the distance between the fire source of the tunnel, obstacle before and after the fire, several sources of fire in the tunnel and ventilation shaft tunnels will be discussed on the critical velocity. Each effect parameter according to a correlation analysis of numerical results obtained using the solver FLUENT software Airpak and then the relationship between dimensionless critical velocity and dimensionless heat release are stated.

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“…While each of these tests has contributed to knowledge, the enormous expense of full-scale tests is often hard to justify, especially as the contribution to knowledge of any individual test is often minimal. For this reason, much recent research in tunnel fire behaviour has been carried out using small scale 'tunnel apparatuses' in established test centres like RISE in Sweden (formerly SP) [18] and the State Key Laboratory of Fire Science (SKLFS) in China [19]. These recent small-scale experiments are carrying on the tradition established in the pioneering research carried out using ducts in the 1960s and 1970s, which is the main focus of this paper.…”

Section: Introductionmentioning

confidence: 99%

Fires in Ducts: A review of the early research which underpins modern tunnel fire safety engineering

Byrne

Georgieva

Carvel

2018

Tunnelling and Underground Space Technology

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Temperature difference due to stratification (K) ∆ Local gas temperature rise (K) ∆ %&'Average gas temperature rise (K) AbstractMuch of the early research which now underpins tunnel fire safety design was carried out experimentally, using small scale ducts. This paper reviews such experiments, mostly carried out in the 1960s, 1970s, and 1980s, highlighting the assumptions and limitations of the early studies, which may have been forgotten as the equations developed have been applied in practice in the subsequent years. The review covers three primary topics; fire propagation under 'turbulent slug flow' conditions, stratification & flame spread, and backlayering & critical ventilation velocity.

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Thermal buoyant smoke back-layering flow length in a longitudinal ventilated tunnel with ceiling extraction at difference distance from heat source

Cited by 89 publications

References 22 publications

Critical Velocity and Backlayering Conditions in Rail Tunnel Fires: State-of-the-Art Review

Critical Velocity and Backlayering Conditions in Rail Tunnel Fires: State-of-the-Art Review

Numerical Simulation of Critical Velocity in Ventilation

Fires in Ducts: A review of the early research which underpins modern tunnel fire safety engineering

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