The behaviour of hot gases flowing within a staircase

Marshall, Norman R.

doi:10.1016/0379-7112(85)90035-9

Cited by 38 publications

(17 citation statements)

References 1 publication

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“…This enabled measurement of the CO 2 gas concentration of the flow in the duct to be made using an infra red gas analyser (Siemens, Ultramat 6, accuracy ± < 1 %). The mass flow rate of gases entering the gas layer in the smoke collecting hood and therefore leaving the hood, was found by using a CO 2 tracer gas technique and calculation method described by Marshall [7]. Vertical velocity profiles of the gas layer flow below the spill edge were made using two pitot-static tubes.…”

Section: Instrumentation and Measurementsmentioning

confidence: 99%

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Physical scale modelling of adhered spill plume entrainment

Harrison

Spearpoint

2010

Fire Safety Journal

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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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Section: Instrumentation and Measurementsmentioning

confidence: 99%

“…The approach described in this article was primarily developed at the Fire Research Station in the UK [6,7] and typically takes the form of reduced scale fires within a physical model. The approach is also described by Klote and Milke [8] and is included in NFPA 92B [9].…”

Section: Physical Scale Modellingmentioning

confidence: 99%

Physical scale modelling of adhered spill plume entrainment

Harrison

Spearpoint

2010

Fire Safety Journal

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“…With heat input at the bottom, it was found that the gases clung to the walls as they flowed up the shaft. In another set of experiments, the hot gases rotated as they flowed up a stair shaft, eventually, becoming relatively homogeneous as they passed the 2 nd floor [40].…”

Section: Tests Conducted Without Sprinkler Protectionmentioning

confidence: 99%

Literature review on enclosure of elevator lobbies

Stroup¹

2003

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“…Marshall [9]. The mass flow rate and convective heat flow rate of layer flow below the spill edge was not determined for unchannelled flows as lateral spread below the balcony caused the flow to become diffuse and non-uniform.…”

Section: Instrumentation and Measurementsmentioning

confidence: 99%

“…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…”

Section: Introductionmentioning

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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The behaviour of hot gases flowing within a staircase

Cited by 38 publications

References 1 publication

Physical scale modelling of adhered spill plume entrainment

Physical scale modelling of adhered spill plume entrainment

Literature review on enclosure of elevator lobbies

A comparison between channelled and unchannelled balcony spill plumes

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