Study on effect of wind on natural smoke exhaust of enclosure fire with a two-layer zone model

Liang, Yi; Gao, Yuxin; Niu, Jiandong; Yang, Sheng

doi:10.1016/j.jweia.2013.05.005

Cited by 22 publications

(12 citation statements)

References 15 publications

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“…Of interest in this chapter are the Sobol sensitivity indices. These indices are often associated to an analysis of variance (ANOVA) decomposition, which consists in the decomposition of the model response into main effects and interactions [21]:…”

Section: Sensitivity Analysis Methodology 21 Global Sensitivity Analmentioning

confidence: 99%

“…Outdoor wind can, however, contribute to the evacuation of smoke and fire extinction in that more smoke is extracted through the corridor when the wind velocity increases. It should nevertheless be mentioned that while ventilation and extraction systems play an important role in fire engineering [15], the efficiency of the smoke extraction system will be reduced and even be invalidated when the outdoor wind velocity is very high and the extraction system is installed in the windward surface of the compartment [21]. In this case, the extraction system cannot perform well, and smoke can spread along the entire compartment through the connected rooms.…”

Section: Outdoor Wind Effect On the Smoke Exhaustmentioning

confidence: 99%

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Numerical Study on the Outdoor Wind Effects on Movement Smoke along a Corridor

Manescau¹,

Chetehouna²,

Serra³

et al. 2020

Fire Safety and Management Awareness

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In this chapter, a numerical investigation is presented in order to highlight the effects of outdoor wind on smoke movements along a corridor in a compartment. For this, the Computational Fluid Dynamics (CFD) code, fire dynamics simulator (FDS), was used to model the reactive flows in interaction with outdoor wind. The wind velocity is taken between 0 and 12.12 m/s, based on the experimental result data come from the work of Li et al. was performed. From numerical data, it was found that smoke stratification state in the corridor depends on Froude number (Fr) and it can be divided into three cases: stable buoyant stratification (Fr < 0.38), unstable buoyant stratification (0.38 ≤ Fr < 0.76), and failed stratification (Fr ≥ 0.76). When Fr ≥ 0.76, smoke stratification is completely disturbed and smoke occupies the entire volume of the compartment, highlighting a risk of toxicity to people. Indeed, it was observed that the velocity of the outdoor wind influences strongly the concentration of O2, CO2, CO, and visibility in the corridor and smoke exhaust. Moreover, for the input data used in the numerical modelling, the global sensitivity analysis demonstrated that the main parameters affecting the smoke temperature near the ceiling are the mass flux of fuel and the activation energy.

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Section: Sensitivity Analysis Methodology 21 Global Sensitivity Analmentioning

confidence: 99%

Section: Outdoor Wind Effect On the Smoke Exhaustmentioning

confidence: 99%

Numerical Study on the Outdoor Wind Effects on Movement Smoke along a Corridor

Manescau¹,

Chetehouna²,

Serra³

et al. 2020

Fire Safety and Management Awareness

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show abstract

“…Although mechanical ventilation is less affected by the outside environment, its system layout is complicated, the economic investment is large, and the maintenance is difficult. In addition, the mechanical ventilation is easy to destroy the smoke layer stratification under the tunnel ceiling, which is very unfavorable to the evacuation of stranded persons in the early stage of tunnel fire. Compared with mechanical ventilation, natural ventilation not only causes less disturbance to the smoke layer stratification, but also is a simple and economical mode.…”

Section: Introductionmentioning

confidence: 99%

“…[23][24][25][26][27][28] Although mechanical ventilation is less affected by the outside environment, its system layout is complicated, the economic investment is large, and the maintenance is difficult. In addition, the mechanical ventilation is easy to destroy the smoke layer stratification [29][30][31][32] under the tunnel ceiling, which is very unfavorable to the evacuation of stranded persons in the early stage of tunnel fire.…”

Section: Introductionmentioning

confidence: 99%

Effects of fire location on the capacity of smoke exhaust from natural ventilation shafts in urban tunnels

et al. 2018

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Summary Investigation of natural ventilation using shafts in tunnels has been receiving more attentions; however, analyses on how fire position influences the natural ventilation performance have rarely been addressed. This study investigated the influence of different fire positions between two shafts on natural ventilation effectiveness in a tunnel by large eddy simulation. The smoke movement characteristics were studied in detail, with systematically varying the fire position between two shafts and the longitudinal wind speed in the tunnel. The typical smoke characteristic parameters, such as temperature distribution, mass flow rate and CO concentration were emphatically investigated. Some special phenomena, such as plug‐holing and smoke bifurcation, were also discussed.

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“…The natural smoke removal will go on properly if thermal buoyancy is the prevailing factor, which determines the conditions in a staircase or inside a large-volume building. However, if the power of developing fire is too low or the wind impact is high the process of natural smoke removal will be significantly disturbed [2,3,4,5,6]. Many researches proved that wind had considerable influence on smoke migration due to causing additional pressure on the facades of a building [2,7,8,9,10].…”

Section: Introductionmentioning

confidence: 99%

Wind Influence on a Building With the Natural Smoke Removal System

Król

2017

Architecture, Civil Engineering, Environment

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A b s t r a c tThe natural smoke removal is a common way of protection of the escape routes in Poland. The operation of such systems is based on the phenomenon of buoyancy. The intensity of this effect depends on the temperature difference between smoke and ambient air. The second factor influencing the natural smoke flow inside a building is wind. The wind influence is significantly important for buildings equipped with smoke removal windows. However, also the other natural smoke removal systems could be affected by the wind impact under adverse ambient conditions. There are the features of the wind described in the first section of the paper. Next, the impact of the wind on a building is shown. Two wind speeds and two wind directions were considered. A building model in the extended computational domain was built. The model was solved with the use of Ansys Fluent. The distributions of dynamic pressure caused by the wind on different facades of the building were presented. The particular attention was paid to the dependence of pressure distribution on the wind direction.S t r e s z c z e n i e Oddymienie naturalne budynków jest powszechnym sposobem ochrony dróg ewakuacyjnych w Polsce. Działanie systemu opiera się na sile wyporu termicznego. Wielkość tej siły uzależniona jest od różnicy temperatury miedzy temperaturą dymu a temperaturą otoczenia. Drugim czynnikiem wpływającym na naturalny przepływ dymu w budynku jest wiatr. Oddziaływanie wiatru ma największe znaczenie dla budynków wyposażonych w okna oddymiające. Jednakże również pozostałe systemy oddymiania naturalnego mogą w niekorzystnych warunkach pozostawać pod wpływem działania wiatru. W pierwszej części artykułu omówiono cechy charakterystyczne wiatru. W dalszej kolejności pokazano jaki wpływ na budynek może wywierać wiatr. Rozważono dwie prędkości napływu wiatru oraz dwa kierunki napływu. Zbudowano model budynku wraz z poszerzona domeną obliczeniowa. Model rozwiązano wykorzystują program Ansys Fluent. Zaprezentowano rozkłady ciśnień, które mogą tworzyć się na fasadach budynku w przypadku działania wiatru na budynek. Zwrócono uwagę na wpływ kierunku napływu wiatru na tworzący się na fasadach układ ciśnień.K e y w o r d s : Natural smoke removal; Wind influence; Ansys Fluent.

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Study on effect of wind on natural smoke exhaust of enclosure fire with a two-layer zone model

Cited by 22 publications

References 15 publications

Numerical Study on the Outdoor Wind Effects on Movement Smoke along a Corridor

Numerical Study on the Outdoor Wind Effects on Movement Smoke along a Corridor

Effects of fire location on the capacity of smoke exhaust from natural ventilation shafts in urban tunnels

Wind Influence on a Building With the Natural Smoke Removal System

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