Actuation of sprinklers at high ceiling clearance facilities

Nam, Soonil

doi:10.1016/j.firesaf.2004.06.004

Cited by 8 publications

(7 citation statements)

References 8 publications

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“…It can be seen that for the sprinklers closest to the center line (sprinklers 1, 2, 5, 6, 9,10), there is a good fit to the correlation by Motevalli and Marks, but for the sprinklers further away (sprinklers 3,7,11,4,8,12) and close to the edges at the side, the ceiling jet is thicker. The reason for such a result is the vortex created when the ceiling jet hits the sides of the raised ceiling.…”

Section: Thickness Of Ceiling Jetmentioning

confidence: 84%

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Influence of Draft Curtains on Sprinkler Activation -- Comparison of Three Different Models

Husted

Holmstedt

2008

Journal of Fire Protection Engineering

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This article investigates the importance of using draft curtains to obtain faster sprinkler activation with three different models-two computational fluid dynamics (CFD) models (CFX 4.4 and fire dynamics simulator (FDS) 4.07) and a zone model (Argos) containing a ceiling-jet formula -for an actual scenario in an entertainment center in Denmark. It is found that a draft curtain has some effect on sprinkler activation, reducing activation time from 8% to 15%, depending on the model implemented. The positions of the sprinklers with in the vertical computational grid of the CFD simulations have a greater influence on the activation of the sprinkler, where FDS is more sensitive than CFX. It is confirmed that heat transfer from the ceiling jet to the ceiling has little influence on the results. The zone model with a ceiling-jet formula gives 10-20% slower sprinkler activation than the CFD results when the sprinkler is close to the ceiling, but is still considered very useful in view of the faster calculation time.

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Section: Thickness Of Ceiling Jetmentioning

confidence: 84%

“…Several tests in this area have been done in the past. Nam [8] studied the actuation of sprinklers in rooms with high ceilings. He concluded that tests using pan fires, with their constant heat release rate (HRR), could lead to incorrect conclusions about the activation of sprinklers when compared to a fire with an increasing HRR.…”

Section: Introductionmentioning

confidence: 99%

Influence of Draft Curtains on Sprinkler Activation -- Comparison of Three Different Models

Husted

Holmstedt

2008

Journal of Fire Protection Engineering

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“…The ignition source was always centered between four sprinklers. The general comments and conclusions from those tests were: (1) no skipping was evident at the four sprinklers surrounding the ignition location, (2) skipping propensity appeared to increase with increasing water discharge density, (3) skipping primarily occurred in the 12 sprinklers surrounding the center four sprinklers, and (4) skipping was affected by the location of the fire plume, as well as the sprinkler type, spacing, and possibly sprinkler design.…”

Section: Introductionmentioning

confidence: 99%

The Skip-resistant Sprinkler Concept -- An Experimental Evaluation

Ditch

Ris

2009

Journal of Fire Protection Engineering

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A sprinkler with a shield designed to mitigate drop impingement from nearby operating sprinklers is shown experimentally to reduce skipping as compared to the same sprinkler without a shield. As described in a companion article, a model for the response time of a shielded sprinkler has been developed and validated with a Plunge Tunnel apparatus. In this article, results from intermediate-scale spray fire tests employing Froude modeling principles with a 1 : 3 scale ratio are used to evaluate sprinkler performance both with and without the shield. By comparing the operation times of adjacent shielded and unshielded sprinklers, the intermediatescale tests can identify test arrangements where the shielded sprinkler operates while the unshielded sprinkler does not operate. The identified arrangements are then used in a full-scale environment where a series of pan fire tests serve as a proof-of-concept that proper shielding of a sprinkler can reduce skipping in terms of both the sprinkler operation pattern and total number of sprinkler operations. This study successfully demonstrates that proper shielding of a sprinkler can significantly reduce skipping.

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“…Prewetting assists in preventing the spread of fire [3] by the following two methods. First, the liquid water film blocks most thermal radiation emanating from the fire plume that is incident to the un-ignited surface; liquid water is fairly opaque to thermal radiation in the wavelengths seen in typical fires [4].…”

Section: Introductionmentioning

confidence: 99%

Rupture of thin liquid films under the influence of external heat flux

Meredith¹,

Vries²

2013

Computational Methods in Multiphase Flow VII

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A thin liquid film completely covering a solid surface has the potential to rupture into rivulets when exposed to external heat flux due to thermocapillary instabilities and vaporization. This has implications for many industrial applications, but particularly for fire suppression. Film rupture drastically reduces the wetted surface area thereby exposing the solid surface to large incident heat fluxes. Recently, a computational fluid dynamics (CFD) model-FireFOAM-has been developed for simulating fire suppression phenomena. The purpose of this study is to investigate and validate FireFOAM's thin film model for predictions of critical heat flux required to induce film rupture. To that extent, vertically flowing film experiments with flow rates ranging form 8.7 g/m/s to 41.3 g/m/s and external heat flux extending from 5 kW/m 2 to 45 kW/m 2 have been simulated. The film heats up non-uniformly and eventually ruptures due to thermocapillary instabilities. Dry regions are formed on the panel as the film pulls together as rivulets. For a given flow rate, the radiative heat flux was varied to identify the 'critical heat flux'. Good qualitative and quantitative match was achieved between model and experiments. At the lower flow rates, even a slight incident heat flux would cause the film to break into rivulets. As the flow rate increased, stronger and stronger heat flux values were necessary to cause film rupture. At very high flow rates, the film remained continuous over the range of heat flux tested. Film rupture was shown to be sensitive to the film inlet conditions.

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Actuation of sprinklers at high ceiling clearance facilities

Cited by 8 publications

References 8 publications

Influence of Draft Curtains on Sprinkler Activation -- Comparison of Three Different Models

Influence of Draft Curtains on Sprinkler Activation -- Comparison of Three Different Models

The Skip-resistant Sprinkler Concept -- An Experimental Evaluation

Rupture of thin liquid films under the influence of external heat flux

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