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Volume 52 (2002)
- Issue 2 Pages 27-
- Issue 1 Pages 1-
Volume 52, Issue 2
Displaying 1-3 of 3 articles from this issue
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Paper
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Simple Predicted Equation of Critical Air Velocity to Stop at the Fire Room Doorway that can be Calculated from Heat Release Rate in Case Flame Penetrates into Hot LayerYuichi WATANABE, Sanae MATSUSHIMA, Tokiyoshi YAMADA2002 Volume 52 Issue 2 Pages 27-36
Published: 2002
Released on J-STAGE: May 09, 2011
JOURNAL FREE ACCESSA series of pressurized smoke control experiments were conducted by using a two-fifths reduced model fire room [2. 7 m × 3. 6 m × 1. 18 m (height)] in part 1 and part 2. A fire source grew the flame reached to the ceiling. So it was assumed that height of hot layer interface was within the range of intermittent flame. The differential pressure distribution and the critical air velocity were measured. For predicting critical air velocity to stop smoke under pressurization smoke control, the differential pressure distribution and the critical air velocity at the fire room doorway shall be well-assessed. Simple predicted equation of critical air velocity to stop at the fire room doorway that can be calculated from heat release rate were studied in part 3.
As a result, the algebraic equation of the critical air velocity of a doorway was obtained by solving the simultaneous algebraic equations of the temperature, the fire plume entrainment and the critical air velocity by pressure difference between rooms. This algebraic equation was in substantially good agreement with the experimental result. The simple prediction equation of the critical air velocity at the fire room doorway, which can be calculated directly from the heat release rate and so on, was obtained through this algebraic equation.View full abstractDownload PDF (578K) -
Hideo OHTANI, Takayoshi OOKUMA2002 Volume 52 Issue 2 Pages 37-42
Published: 2002
Released on J-STAGE: May 09, 2011
JOURNAL FREE ACCESSTo investigate flash flame spread mechanisms over napped fabrics, dependence of the flame spread on depth or density of a napped layer was studied experimentally by using napped absorbent cotton. The flame spread rate was found to increase with the depth and decrease with the density of the napped layer.
Models of the spreading flame downward or upward over a napped layer of a vertical plate were derived from video images of the observed flames. By comparing the models with experimental results, it was revealed that the flame spread rate is governed by radiative heat transfer in the case of downward flame spread and by convective heat transfer in the case of upward flame spread.View full abstractDownload PDF (977K) -
Yukio YAMAUCHI, Atsushi MAMMOTO2002 Volume 52 Issue 2 Pages 43-50
Published: 2002
Released on J-STAGE: May 09, 2011
JOURNAL FREE ACCESSMany parameters are involved in affecting the response time of the smoke detector for a given fire in an enclosure, i. e. the heat release rate and the particulate production rate of the fire source, the ceiling height and the radial distance from the fire source, the confined ceiling area of the enclosure, as well as the response characteristics of the detector. A simple prediction method is desirable for performance based designing of the fire alarm system. The calculation method described here uses a simple correlation of smoke concentration in the ceiling-jet, which takes into account the smoke accumulation effect in the upper part of the enclosure, the particulate response characteristics of the detector, and the delay of smoke entry into the detector' s detection chamber. Comparison of calculation with experimental data showed a good agreement. This calculation method is applicable not only to the flaming fires, but also to the smoldering fires.View full abstractDownload PDF (521K)
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