Atrium buildings: Calculating smoke flows in atria for smoke-control

doi:10.1016/0379-7112(87)90013-0

Fire Safety Journal

Volume 12, Issue 1, February 1987, Pages 9-35

https://doi.org/10.1016/0379-7112(87)90013-0 Get rights and content

Abstract

This paper presents methods for predicting, to an accuracy sufficient for smoke-control design purposes, smoky gas flows leaving a compartment on fire and passing into an atrium. It discusses the height of any flames that might be present in the atrium, as well as the temperatures in those flames to which building (or other) materials might be exposed. It presents methods for calculating entrainment into the thermal plume (rising against the wall or out in the open). Much of this is also applicable to the exterior of buildings in the absence of wind.

It further presents methods for calculating the time for smoke to fill an atrium to close above the fire, both with and without the presence of venting. It gives formulae for calculating the required capacity of either powered or natural extract for steady-state ‘throughflow’ smoke ventilation.

It is concluded that, apart from exceptional circumstances, it is not usually feasible to design successful smoke-ventilation systems to keep the base of the atrium's buoyant layer more than 8 – 16 m above the fire-room opening. In practice, this means that ‘throughflows’ smoke ventilation will rarely allow escape routes to be open to the atrium above the fourth or fifth floor.

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A mathematical model on adjacent smoke filling involved sprinkler cooling to a smoke layer
2011, Safety Science
Citation Excerpt :
Natural smoke filling refers to a smoke filling process without any external interference. For such, some mathematical models have been developed by researchers (Tanaka and Yamana, 1985; Morgan and Hansell, 1987; Cooper, 2002; Chow, 1997; NFPA204M, 2002; Yuan and Fan, 1998; NFPA92B, 2009; Mowrer, 1999; Li, 2001) which are theoretically derived from the mass and energy conservations. These models, including ASET model, NFPA92B model and Tanaka model, are essentially based on tow-zone conception.
Conventional two-zone model determines the smoke filling time in buildings without considering the cooling effect of sprinkler spray on the smoke layer. However, many buildings have been required to install the sprinkler systems by fire codes. So, the conventional zone model was not able to accurately predict the development of smoke layer height in a sprinklers involved fire. In order to improve the prediction, the current zone model is revised with a new mathematical model developed by taking the sprinkler cooling effect into account. The heat transfer between smoke layer and sprinklers spray was mathematically calculated. By using the mathematical model, the smoke filling time in an adjacent space under the sprinkler cooling effect are calculated. A set of experiments were carried out to validate the model. The smoke layer height was experimentally measured. Results show that the model predictions agree well with the experimental results. The smoke filling becomes slower due to the reduced volumetric smoke flow under sprinkler cooling. The variation of sprinkler operating pressure has little influence on the smoke filling since the cooling gets less effective as the operating pressure increases.
Experimental studies on natural smoke filling in atrium due to a shop fire
2005, Building and Environment
Citation Excerpt :
Therefore, studying the smoke filling process in an atrium due to a shop fire with smoke spilling out is important for designing appropriate fire protection systems. When a fire occurs in a shop adjacent to the atrium, a balcony spill plume [e.g. 3–10] will be formed first and then start to fill up the atrium. Balcony spill plume expressions for configuration as shown in Fig. 1 are commonly used for practical design.
How smoke spilling out of a shop fire would fill up an atrium has been studied experimentally in this paper. Full-scale burning tests were carried out in the PolyU/USTC Atrium constructed in Hefei, China. Since balcony spill plume expressions appeared in the literature might not be applicable for a shop fire with finite width, two plume models for smoke spilling out of a shop fire inside an atrium were proposed and assessed. An equation on studying the smoke layer interface height with a two-layer approach was derived.
Two-dimensional smoke flows from fires in compartments: some engineering relationships
1992, Fire Safety Journal
Conventional formulae for flows of hot gases from openings in a compartment on fire are presented in a way which may well simplify the correlation of data for a wide range of conditions.
The paper also establishes a context into which the McCaffrey-Quintiere regression formula (McCaffrey, B. J., Quintiere, J. G. & Harkleroad, M. Fire Technol., 17 (1981)2) for the upper layer gas temperature can be fitted and the distortions of conventional scaling laws, reported by Blay et al. (Blay, D., Turhault, J. L. & Jourbert, P. Modelling Smoke Movement in Corridors. New Technology to Reduce Fire Losses and Costs, ed. S.J. Grayson & D.A. Smith. Elsevier Applied Science, Barking, 1986) can be explained.
Comments on "atrium buildings: Calculating smoke flows in atria for smoke-control design"
1988, Fire Safety Journal
Atrium building smoke flows
1988, Fire Safety Journal
The horizontal flow of buoyant gases toward an opening
1986, Fire Safety Journal
Well-established equations exist for calculating mass flow rates of thermally buoyant gas layers out of openings. The present work presents an alternative method of deriving such an expression in two-dimensional flows for non-uniform approach velocities induced by the layer's buoyancy. The method makes a number of assumptions, leading to the application of the total energy equation at a virtual vena contracta outside the opening.
The resulting mass flow formula is quantitatively equal to the established formula for a wide exit and C_d = 0.6, i.e., for a deep downstand, and so agrees with published data as well as does the existing formula. The two formulae diverge for different values of C_d and for gas flows much hotter than 300 °C.
Since the new formula gives more pessimistic (i.e., larger) mass flow rates for wide openings with no downstand (and hence larger extract fans or vent areas in the smoke reservoir “downstream” of those openings), it is suggested that it should be used by designers of smoke ventilation systems in such circumstances.
It is also deduced that, for “realistic” buoyant-layer flows, the mass weighted average $θ$ is typically 0.73 θ_maxforθ_max ⩽ 300 °C.

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Atrium buildings: Calculating smoke flows in atria for smoke-control

Abstract

Fire Safety J.

Fire Safety J.

Combust. Flame

Fire Safety J.

Fire Safety J.

Fire Safety J.

Combust. Flame

Combust. Flame

Fire Safety J.

Fire Safety J.

Atrium Buildings, Development and Design

The Andraus Building fire in São Paulo, Brazil

Fire Prev.

An strium fire

Fire J.

Atrium fire proves difficult to ventilate

Fire J.

Design principles for smoke control in buildings

Fire Surveyor

Atrium buildings: A Fire Service view

Fire Surveyor

Atriums

The Building Official and Code Administrator

Smoke movement in atria

Fire Prot. (South Africa)

Life safety considerations in atrium buildings

Fire Prev.

Estimating Safe Available Egress Time from Fires

Smoke Control Methods in Enclosed Shopping Complexes of One or More Storeys: A Design Summary

Fire sizes and sprinkler effectiveness in shopping complexes and retail premises

Fire Surveyor

Fully-developed Compartment Fires