The spill plume in smoke control design

This work provides new experimental data to characterise entrainment of air into adhered thermal spill plumes using physical scale modelling. For the two-dimensional plume, the rate of entrainment with respect to height of rise is approximately half that of an equivalent twodimensional balcony spill plume. For the three-dimensional plume, the rate of entrainment appears to be linked to the plume behaviour, which has been characterised in terms of the width and depth of the layer flow below the spill edge. In general, a layer flow below the spill edge that is shallow compared to its width will tend to adhere to the wall above the opening compared to flows whose depth approaches its width. This work proposes new empirical entrainment design formulae that have been developed on a more general basis compared to existing methods.

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“…Thomas et al [13] used a rigorous dimensional analysis to develop a simplified spill plume formula in the form given by,…”

Section: Discussionmentioning

confidence: 99%

“…z attach ) was determined from visual observations. In an attempt to describe the plume behaviour beyond the spill edge, Figure 8 Thomas et al [13] is used in the analysis to be consistent with approach used by Harrison and Spearpoint [15] for the analysis of 3-D balcony spill plumes.…”

Section: Plume Behaviourmentioning

confidence: 99%

Physical scale modelling of adhered spill plume entrainment

Harrison

Spearpoint

2010

Fire Safety Journal

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“…One of the most important criteria in the design of these SHC systems is the smoke free height in the atrium. Many experimental and numerical studies have already been performed in this context [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Numerical study of smoke extraction for adhered spill plumes in atria: Impact of extraction rate and geometrical parameters

Tilley

Merci

2013

Fire Safety Journal

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In case of fire in an atrium, a smoke and heat control (SHC) system can be designed to improve safety inside the atrium. An important design criterion is the smoke free height in the atrium. This smoke free height is the result of a number of parameters, of which the fire heat release rate (HRR), the SHC extraction mass flow rate, the position of the extraction device or opening and the size and position of openings for make-up air are of primary importance. In the present paper, an extensive numerical study, based on Computational Fluid Dynamics (CFD), is presented in which these parameters are varied. The presence of a downstand or balcony is not covered in the study at hand. From the results, a correlation is presented for adhered spill plumes in atria without downstand, relating the smoke extraction rate to the smoke free height in the atrium. The smoke layer in the atrium is illustrated to become multidimensional beyond a certain threshold value of the smoke extraction rate and existing correlations, which do not take this phenomenon into account, are not conservative. The position and exact size of the make-up air inlet openings are shown not to affect the observations, as long as the openings are sufficiently large.

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“…In the past, several authors [1][2][3][4][5][6][7][8][9] developed formulae to calculate the required smoke mass flow rate ( m ) to be extracted at the ceiling of the atrium, in order to ensure a certain smoke free height (z s ) above the spill edge. The (convective) fire heat release rate ( conv Q ) and a length scale parameter of the atrium (typically a width W) appear in all these formulae.…”

Section: Introductionmentioning

confidence: 99%

On the extrapolation of CFD results for smoke and heat control in reduced-scale set-ups to full scale: Atrium configuration

Tilley

Rauwoens

Fauconnier

et al. 2013

Fire Safety Journal

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It is common practice to use reduced-scale experiments to develop formulae for the design of smoke and heat exhaust ventilation systems. Implicitly, up-scaling of results is assumed justified. A similar approach can be adopted with numerical simulations, i.e. a reduced-scale setup can be up-scaled to compare results to full-scale observations. However, both in numerical simulations and in experiments, scaling must be done in a proper way. The classical method for up-scaling results obtained in fire related experiments is based on preservation of the Froude number only. The present paper, focusing on the up-scaling of results by means of a series of CFD simulations of fire-induced flows in an atrium configuration, confirms this to be justified as long as the flows in both the reduced-scale and full-scale configurations are sufficiently turbulent. If this is not the case, it is illustrated that other dimensionless numbers must also be preserved in scaling, in addition to the Froude number.2

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The spill plume in smoke control design

Cited by 37 publications

References 13 publications

Physical scale modelling of adhered spill plume entrainment

Physical scale modelling of adhered spill plume entrainment

Numerical study of smoke extraction for adhered spill plumes in atria: Impact of extraction rate and geometrical parameters

On the extrapolation of CFD results for smoke and heat control in reduced-scale set-ups to full scale: Atrium configuration

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