Numerical simulation on cooling of the fire-induced air flow by sprinkler water sprays

Chow, Wan Ki; Fong, Nai Kong

doi:10.1016/0379-7112(91)90023-r

Cited by 35 publications

(19 citation statements)

References 20 publications

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“…[ PI The mean droplet size d, is calculated by: (6) where the Weber number, We, is expressed in terms of the nozzle diameter, d,, velocity of the water column, ur, at the sprinkler orifice which depends on the flow rate fw, and the surface tension of water droplet 0 : ' ' d we = p,u; 2! 0 with…”

Section: Theorymentioning

confidence: 99%

Simulation of sprinkler—hot layer interaction using a field model

Chow

Cheung

1994

Fire and Materials

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This paper reports a study of the interaction of a sprinkler water spray with the fire-induced hot layer using the field modelling technique. Data obtained in the large test room of the recent Swedish experiments reported by Ingason and Olsfon (1992) are used to validate the results. The problem is divided iuto a gas phase and a liquid phase. For the gas phase, the set of conservation equations for mass, momentum and enthalpy of air flow induced by the fire is solved numerically using the Pressure Implicit Splitting Operator (PISO) algorithm. For the liquid phase, the sprinkler water spray is described by a number of droplets with initial velocity and diameter calculated by empirical expressions for the nozzle at different operating water pressures and flow rates. The trajectory of each droplet is calculated by solving the equation of motions, by including the dragging and heat transfer with the hot layer. The water droplet is assumed to be non-evaporating and only the source terms in the gas momentum and enthalpy equations of the air flow included the interaction effects with water droplets, ie. the 'Particle-Source-in-Cell' method. The predicted results include the gas flow, temperature and smoke concentration field; the shape of the water spray; and some relevant macroscopic parameters such as amount of convective cooling, drag-to-buoyancy ratio, etc. The average smoke layer temperature and the smoke layer interface height are also calculated. The effect of the mean droplet size on those parameters is illustrated. Finally, a comparison of the water density received at floor Ievel in cases with and without the fire is made.

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Section: Theorymentioning

confidence: 99%

Simulation of sprinkler—hot layer interaction using a field model

Chow

Cheung

1994

Fire and Materials

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“…Earlier studies are complicated and rely on knowledge of droplet diameter and sprinkler spray distribution which can only be measured using complicated and expensive techniques [2][3][4][5][6][7][8][9][10]. These studies have important implications, but the inclusion of droplet size and distribution as variables make the work impractical for use as an engineering tool because of the difficulty in measuring these parameters.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Sprinkler Sprays on Fire Induced Doorway Flows

et al. 2009

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Performance based methodologies are becoming increasingly common in fire safety due to the inability of prescriptive codes to account for every architectural feature. Fire Sprinkler suppression systems have long been used to provide property protection and enhance life safety. However, very few methodologies exist to account for the impact of sprinkler sprays on fire scenarios. Current methods are extremely complicated and difficult to use as an engineering tool for performance based design. Twenty-four full scale fire tests were conducted at Tyco Fire Suppression & Building Products Global Technology Center to determine a simple method for accounting for the impact of a single residential sprinkler on fire induced doorway flows. It was found that a spraying sprinkler reduced the mass flows at the doorway while maintaining two stratified layers away from the sprinkler spray. The mass flow reduction was consistent and could be predicted through the use of a simple buoyancy based equation. The current study suggests that the buoyancy equation can be altered through the use of a constant cooling coefficient (equal to 0.84 for a Tyco LFII (TY2234) sprinkler) based on the test results reported in this paper. This study is a proof of concept and the results suggest the methodology can be applicable to similar situations.

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“…Morgan and Baines [1,6] further included the convective heat transfer from the smoke layer to the sprinkler spray in the model, which was ignored by Bullen. Numerical modeling was conducted later by Alpert [7], Chow [8][9][10], Hoffmann [11] and Gardiner [12]. Interaction of sprinkler spray with ventilation was also studied by Heselden [13], Hinkley [14] and McGrattan [15].…”

Section: Introductionmentioning

confidence: 99%

“…The smoke logging is a risk to evacuation and fire fighting [1][2][3][4][5][6][7][8][9][10]. However, this behavior was not considered in the most popular zone fire models, such as the latest version of CFAST (6.0).…”

Section: Introductionmentioning

confidence: 99%

A mathematical model on interaction of smoke layer with sprinkler spray

Huo

et al. 2009

Fire Safety Journal

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A mathematical model was developed for predicting the downward descending behavior of the buoyant smoke layer under sprinkler spray. The behavior of the smoke layer was determined by considering the interaction between the drag force of the sprinkler spray and the buoyancy force of the hot smoke layer itself in the spray region. The smoke layer may be pulled down with its thickness increased at the center of the spray region due to the cooling and drag effects of the sprinkler spray, thus to form a downward "smoke logging" plume. In the mathematical model developed in this paper, the critical condition under which the smoke layer lost its stability, as a serious concern, was predicted. Additionally, the length of the downward plume, which was rarely investigated before, was also further calculated.

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Numerical simulation on cooling of the fire-induced air flow by sprinkler water sprays

Cited by 35 publications

References 20 publications

Simulation of sprinkler—hot layer interaction using a field model

Simulation of sprinkler—hot layer interaction using a field model

Investigation of Sprinkler Sprays on Fire Induced Doorway Flows

A mathematical model on interaction of smoke layer with sprinkler spray

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