Measurements of balcony smoke flow

Law, M.

doi:10.1016/0379-7112(95)00011-h

Cited by 30 publications

(24 citation statements)

References 3 publications

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“…Law [15] subsequently used a similar analysis using further experimental data from Hansell et al [14]. This analysis led to a revised correlation as given by Equation 5.…”

Section: Methods By Lawmentioning

confidence: 99%

Entrainment of Air into a Balcony Spill Plume

Harrison¹,

Spearpoint²

2006

Journal of Fire Protection Engineering

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This paper examines various uncertainties relating to calculation methods for the balcony spill plume. The approach of physical scale modelling was used in the analysis. Comparisons are made between the experimental results and the predictions made using these calculation methods. This work has demonstrated that the presence of a downstand at the spill edge of a compartment opening appears to have little effect on the entrainment of air into the subsequent spill plume. A simplified spill plume formula has also been developed to predict the mass flow rate of gases, which inherently includes entrainment of air into the free ends.

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“…Law [15] subsequently used a similar analysis using further experimental data from Hansell et al [14]. This analysis led to a revised correlation as given by Equation 5.…”

Section: Methods By Lawmentioning

confidence: 99%

Entrainment of Air into a Balcony Spill Plume

Harrison¹,

Spearpoint²

2006

Journal of Fire Protection Engineering

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“…Entrainment into unchannelled balcony spill plumes is not so well understood. A very limited data set obtained from 1/10 th physical scale model experiments by Hansell et al [3] was subsequently analysed by Law [4] to give simplified design guidance for this scenario. This guidance is given by CIBSE [5] and remains in the current version of NFPA 92B [6] following further full scale experiments by Lougheed et al [7].…”

Section: Entrainment Of Air Into Channelled 2-d and 3-d Balcony Spillmentioning

confidence: 99%

A comparison between channelled and unchannelled balcony spill plumes

Harrison

Spearpoint²

2010

Building Services Engineering Research and Technology

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The use of channelling screens in smoke management design can reduce balcony spill plume entrainment by restricting smoke spread under the balcony. The omission of channelling screens can gave rise to a greater lateral extent resulting in a change in the entrainment conditions. This work provides new experimental data using physical scale modelling to enable a comparison between channelled and unchannelled plumes. The lateral spread for unchannelled plumes was found to be dependent upon the velocity of the flow from the fire compartment opening. The measured entrainment for plumes without screens was greater than that from equivalent plumes with screens and the relative difference in entrainment increased as the width of the fire compartment opening decreased. A simple approximation to predict entrainment for unchannelled plumes from wide fire compartment openings is proposed. INTRODUCTIONThe design of smoke management systems requires appropriate entrainment calculation methods to predict the volume of smoky gases produced in a fire in order to determine the required exhaust fan capacity or ventilator area for a design clear layer height. Consideration is often given to entrainment of air into a smoke flow from a compartment opening that subsequently spills at a balcony edge and then rises into an adjacent atrium void. This type of thermal plume is commonly known as a balcony spill plume (see Figure 1). If the smoke flow from the compartment opening is allowed to pass unrestricted under a balcony, it will spread laterally. The smoke flow will spill at the balcony edge (i.e. the spill edge) and rise into the atrium space with a large surface area over which entrainment of air occurs. Spill plumes that do not include entrainment into the ends of the plume are known as two-dimensional (2-D) plumes and those that include end entrainment are known as three-dimensional (3-D) plumes. The approach of physical scale modelling is well established and has been used in many studies of smoke movement in buildings. The approach described in this article was primarily developed at the Fire Research Station in the UK [8,9] and typically takes the form of reduced scale fires within a physical model. The approach is also described by Klote and Milke [10] and is included in NFPA 92B[6]. Measurements are generally made of temperature, velocity and gas concentrations, in addition to visual observations. To ensure that the results can be extrapolated to full scale, the physical scale model used in this study was designed to meet the scaling laws set out by Thomas et al. [8]. This is effectively a modified Froude number scaling and requires that the equivalent flows are fully turbulent on both full and model scale. THE EXPERIMENTS The physical scale modelThe 1/10 th physical scale model used (see Figure 2) 5A steady fire source was generated by supplying Industrial Methylated Spirits (IMS) into a metal tray within the fire compartment at a controlled and measured rate. The total heat release rate of the fire was determined...

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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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Measurements of balcony smoke flow

Cited by 30 publications

References 3 publications

Entrainment of Air into a Balcony Spill Plume

Entrainment of Air into a Balcony Spill Plume

A comparison between channelled and unchannelled balcony spill plumes

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

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