Fire induced flow through an opening

Prahl, Joseph M.; Emmons, Howard W.

doi:10.1016/0010-2180(75)90109-1

Cited by 144 publications

(71 citation statements)

References 2 publications

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“…orifice discharge coeffic ient gas specifi c heat (J/kg' K) height of thermal discontinuity above floor (m) plume Froude number = uJ/g'Yo gravitational accelerati on (9.8 m/s 2 ) height of enclosure (m) height of door opening (m) entrainmen t coeffi cient gas/air How rate (kg/s) height of ne utral plane above floor (m) pressure (torr, N/m 2 ) pressure difference, enclosure to ambient P-P AMB (torr, also given as N/m 2 ) heat release rate (k W) radial distance from plume axis gas temperature (OC, K) temperature difference eC) gas burner flow velocity (m/s) gas/air velocity (m/s) door opening width (m) entrained flow in plume (kg/s) gas burner flow rate = pf7T1o u f height above floor (m) radius of gas burner (m) distance above or below neutral plane gas densit y (kg/m 3 ) fu el property defined by equation (9) 1 . Introduction Present e nclos ure-fire modeling incorpora tes a hydrauli csorifice approach for calculation of th e How in a nd out of th e opening [1,2,3].1 Due to th e hot gases present in the upper portion of the room a pressure difference with respect to the ambient hydrostati c pressure is developed across the opening which is responsible for driving th e How.…”

Section: Nomenclature Door Opening Area (M 2 )mentioning

confidence: 99%

“…Introduction Present e nclos ure-fire modeling incorpora tes a hydrauli csorifice approach for calculation of th e How in a nd out of th e opening [1,2,3].1 Due to th e hot gases present in the upper portion of the room a pressure difference with respect to the ambient hydrostati c pressure is developed across the opening which is responsible for driving th e How. The gas in th e room is ass umed stationary and the How ra te is determined using Bernoulli's equation with an appropri a te orifice coefficient.…”

Section: Nomenclature Door Opening Area (M 2 )mentioning

confidence: 99%

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Static pressure measurements of enclosure fires

McCaffrey¹,

Rockett²

1977

J. RES. NATL. BUR. STAN.

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Some enclosure-fire s tati c pressure me asurements are presented for both full a nd sca le mode l rooms and are compared with the present hydra uli cs-orifice flow model for fire induced flows into and out of enclosures. Results indicate that the vertical pressu re diffe renti al (enclosure to ambient) follow s the expected hydrostati c distribution qUite well and accura tely reflects the doorway Inflow and outflow gas velocities. .Measure me nt of ceiling a nd floor diffe rential pressure using different numbers of gas burners yields ins ight Int o gross plume e ntrainment and Illus trates how the neutra l p la ne and thermal di scontinuit y vary with upper gas temperature. Corre la ting upper gas tempe ra ture with fire s ize and enclosure he ight ma kes it possible to pred ict at wha t heat release rat e a give n enclosure mi ght become fully involved, i. e., by using the temperature at which the the rma l discontinuity approac hes th e floor.In te rms of present fire plume modeling la rge e ntra inment coeffi cie nt s (0 .3-0.4) are required in order to reproduce the e nc los ure fl ows for both the s ma ll and large scale resu lt s. A noted defi cie ncy in the plume mode l appears In the small sca le results wh e re the data suggest that the e ntrainment s hould exhibit a much stronger dependence on th e fu el injecti on rate tha n that pred icted by the th eory.Key words: Buoyancy pressure; e nclosure fires; entrai nme nt; fire ind uced flow s; models; physica l sca le; plumes.Nomenclature door opening area (m 2 ) orifice discharge coeffic ient gas specifi c heat (J/kg' K) height of thermal discontinuity above floor (m) plume Froude number = uJ/g'Yo gravitational accelerati on (9.8 m/s 2 ) height of enclosure (m) height of door opening (m) entrainmen t coeffi cient gas/air How rate (kg/s) height of ne utral plane above floor (m) pressure (torr, N/m 2 ) pressure difference, enclosure to ambient P-P AMB (torr, also given as N/m 2 ) heat release rate (k W) radial distance from plume axis gas temperature (OC, K) temperature difference eC) gas burner flow velocity (m/s) gas/air velocity (m/s) door opening width (m) entrained flow in plume (kg/s) gas burner flow rate = pf7T1o u f height above floor (m) radius of gas burner (m) distance above or below neutral plane gas densit y (kg/m 3 ) fu el property defined by equation (9) 1 . Introduction Present e nclos ure-fire modeling incorpora tes a hydrauli csorifice approach for calculation of th e How in a nd out of th e opening [1,2,3].1 Due to th e hot gases present in the upper portion of the room a pressure difference with respect to the ambient hydrostati c pressure is developed across the opening which is responsible for driving th e How. The gas in th e room is ass umed stationary and the How ra te is determined using Bernoulli's equation with an appropri a te orifice coefficient. Additionally th e gas Jlow in and ou t of th e e nclos ure is co upled via entra inmen t of th e [ire plume. Figures 1 a nd 2 illustrate th ese ideas sc he mati cally. A s tep functi...

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Section: Nomenclature Door Opening Area (M 2 )mentioning

confidence: 99%

Section: Nomenclature Door Opening Area (M 2 )mentioning

confidence: 99%

Static pressure measurements of enclosure fires

McCaffrey¹,

Rockett²

1977

J. RES. NATL. BUR. STAN.

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“…The mass flow rates at the opening, m D and m a , can be calculated by using the temperature of the compartment [5] and the flow velocity of the openings. However, it is impossible to use these two parameters to measure the mass flow rates of the fire plume, m P , and the downward airflow, m E .…”

Section: Measurement Methods For Mass Flow Rate Based On Gas Analysismentioning

confidence: 99%

A Study on Smoke Behavior in a Compartment with Sprinkler System Activation-Simple Predictive Method on Mass Flow Rates Based on Experimental Study-

Ota

Kuwana

Ohmiya

et al. 2009

Fire Science and Technology

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Sprinklers generate a flow of downward moving gases from smoke in the upper layer of a two-layer zone within a compartment. It is necessary to determine quantitatively the flow of downward-moving gases and fire plume in order to calculate smoke behavior in a compartment with sprinkler activation. As a first, this study proposes a measurement technique of mass flow rate based on the gas analysis method since it is difficult to understand through conventional methods. Experiments were conducted on a full scale and the following results were obtained; 1) the mass flow rate of the fire plume grows with sprinkler activation and a flow of downward-moving gases grows as the heat release rate decreases and the amount of sprinkler supplied water increases.2) A relation between the ratios of the mass flow rate penetrated to lower layer by water droplets to the mass flow rate of watering supply from SP, and of the upper (smoke) layer and the lower layer. As a result, the mass flow rate penetrated to lower layer can be computed when the mass flow rate of watering supply from SP and temperature at the smoke and lower layers are known. KEYWORDS:

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“…The mass flow rate through an opening can be calculated from the temperature of the compartment and the flow rate of the openings [2,3]. Also, as a method for In this study, the in/out flow rates through the opening, fire plume flow rate and downward flow rate are measured in order to explore the smoke behavior in a compartment during the SP system activation.…”

Section: Mass Flow Rate Measurement Approach Based On Gas Analysismentioning

confidence: 99%

A Study of Smoke Behavior in a Compartment with Sprinkler System Activation-Theory and Validity on the Flow Rate of the Fire Plume during Sprinkler System Activation-

Ota

Yamaguchi

Kuwana

et al. 2007

Fire Science and Technology

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OBJECTIVE AND BACKGROUNDIn Japan, it is required by law to install a sprinkler system (hereafter, SP System) in accordance with the use of the building and its size. In general, the purpose of the SP System is to extinguish fires, and therefore most research reports are related to fire extinguishing. However, the influence of the SP system activation on the smoke layerhas not yet been sufficiently assessed.It is difficult to quantify the extinguishing time for SP systems, and the prediction of the behavior of the flames and the smoke, which is restricted by the SP systems, is still in the process of preliminary research. In order to be able to apply the influence of fire extinguishing equipment on the smoke behavior to the performance design, the effects of the sprinkling system need to be quantified. The successful evaluation and application of the fire suppression effects would allow for a more rational assessment of the fire performance, which is currently evaluated by assuming the emergence of an uncontrolled fire. Consequently, this would result in greater flexibility with respect to fire prevention planning Therefore, this experimental study examined the influence on the smoke layer during sprinkling, in order to obtain information about smoke behavior during the SP system activation. In this paper, the changes occurring in the fire plume after sprinkling are reported. Figure 1 is a conceptual diagram of the smoke behavior within the fire compartment during the SP system activation. In Figure 1, the positions of the fire source and the water application are intentionally separated in order to illustrate the influence of the sprinkler on the smoke movement. Furthermore, for the sake of simplicity, the inside of PROPERTIES OF THE FIRE MODEL ASSUMED IN THIS STUDY

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Fire induced flow through an opening

Cited by 144 publications

References 2 publications

Static pressure measurements of enclosure fires

Static pressure measurements of enclosure fires

A Study on Smoke Behavior in a Compartment with Sprinkler System Activation-Simple Predictive Method on Mass Flow Rates Based on Experimental Study-

A Study of Smoke Behavior in a Compartment with Sprinkler System Activation-Theory and Validity on the Flow Rate of the Fire Plume during Sprinkler System Activation-

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