Bulletin of Japan Association for Fire Science and Engineering
Online ISSN : 1883-5600
Print ISSN : 0546-0794
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Paper
  • Yasushi OKA, Hideyuki OKA, Masami IIZUKA
    2017 Volume 67 Issue 1 Pages 1-8
    Published: 2017
    Released: July 13, 2018
    JOURNALS FREE ACCESS
    As a fire plume becomes a driving force for diffusion of heat and combustion products in an early stage of fire, engineering correlations on fire plume are widely utilised as tools to assess fire safety of onshore buildings and plants. In the offshore environment, however, fire plume properties are considerably different from those in a compartment of onshore building because of the influence of complex ship motions. As a preliminary step, we experimentally investigate the temperature characteristic of the plume formed above the fire source with simple harmonic oscillation in unconfined space where the direction of action of gravity does not change with time. The time-averaged temperature attenuation along the centre of the fictitious rectangular fire source in vertical direction was made clear using limited experimental data. The height where the attenuation property of temperature rise changes from line fire plume to axisymmetric plume was determined based on the calculated temperature field, which was obtained by applying the conventional far-field Gaussian plume correlation for an idealised point source to the temperature field formed above a harmonically oscillating fire source. It has been clarified that an empirical correlation for this transition height can be expressed as a function of amplitude and representative length of the fictitious rectangular fire source.
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  • Yusuke SHINTANI, Tsutomu NAGAOKA, Yoshikazu DEGUCHI, Kazunori HARADA
    2017 Volume 67 Issue 1 Pages 9-16
    Published: 2017
    Released: July 13, 2018
    JOURNALS FREE ACCESS
    Model scale experiments on fire spread between spaced three urethane foam blocks under smoke layer were conducted. Time to fire spread between blocks, mass loss rate of urethane foams, heat flux and smoke layer temperature were measured. The ceiling height and separation distance between specimens were varied. When the separation distance was small fire spread was occurred by flame touching. When the distance was large, it was occurred by piloted ignition. Times to fire spread were decreased as the ceiling heights are decreased because downward vertical flame spread rate of urethane foam ignited at first, which increase radiation heat flux to the adjacent urethane foam, were increased. Heat release rate calculated by mass loss rate of urethane foam ignited secondary increased considerably when the ceiling height is low. Because flame spread rate on horizontal and vertical surface were increased by the high surface temperature at the time for a fire to spread. For this reason the maximum heat release rates were almost three times of those of urethane foam measured in an open air in earlier study.
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  • Masaki NOAKI, Yoshifumi OHMIYA, Jun-ichi SUZUKI
    2017 Volume 67 Issue 1 Pages 17-30
    Published: 2017
    Released: July 13, 2018
    JOURNALS FREE ACCESS
    A series of experiments of heating columns in a localized fire was conducted to comprehend effects of a water application on the thermal response of the columns exposed to surrounding fire. The objectives of this study are to measure and analyze the vertical distribution of incident heat flux on and temperature in a column from a localized fire in an actual scale, including the effects of the sprinkler system.
    Specimens were designed to replicate a full-scale column (Size: 3.1 m high, 0.3 m wide, and 0.3 m deep) in buildings. The fire severity (heat release rate of fire source), water flow rate from a sprinkler head (80 L/min) in the experiments, as important parameters in a localized fire, were determined to demonstrate sever or typical conditions in the experimental capacity, respectively.
    As a result, indicated value of heat flux meter on the column and temperatures of wall surface covered with galvanized steel sheets decreased immediately after the sprinkler system was activated.
    After the indicated value of heat flux meter and temperature maintained constant values for a while (transition state), these values decreased again to another constant level (steady state). The heat flux reduced 13~23 kW/m2 by sprinkler system in transition state as the result of calculating the heat balance of wall surface (galvanized steel sheet).
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  • Masashi KISHIUE, Jun-ichi YAMAGUCHI, Seiji OKINAGA, Ken MATSUYAMA, Tak ...
    2017 Volume 67 Issue 1 Pages 31-38
    Published: 2017
    Released: July 13, 2018
    JOURNALS FREE ACCESS
    Measurement methods necessary to verify the hypothesis about smoke shielding performance proposed by the previous paper were suggested and the validity of these methods was inspected. These methods suggested in this paper were shown below with measurement items necessary for the verification of the hypothesis.
    1) The wind velocity of the ingredient vertical for the upper surface and the perpendicular surface in the smoke shield opening
    It is measured with a directional anemometer which was installed so that direction of measurement became perpendicular to a measurement surface.
    2) Static pressure difference
    The some newly developed devices were installed so that the angle to be formed of each device becomes less than 90 degrees and the maximum of measurement values was considered as the static pressure difference.
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  • Masashi KISHIUE, Jun-ichi YAMAGUCHI, Seiji OKINAGA, Ken MATSUYAMA, Tak ...
    2017 Volume 67 Issue 1 Pages 39-48
    Published: 2017
    Released: July 13, 2018
    JOURNALS FREE ACCESS
    For the purpose of elucidating the influence that the difference in aeration method gave in smoke shield performance, an aeration experiment at the normal temperature was carried out using a full-scale model like the fire experiment. By the experiment, static pressure differences between aeration room and outside and The wind velocity of the ingredient vertical for the upper surface and the perpendicular surface in the smoke shield opening were measured. As a result, the following things were shown.
    1) Non-dimensional static pressure difference P* is almost proportion to smoke shield performance.
    2) Upper aspect non-dimensional wind velocity ratio Vu* is almost proportion to smoke shield performance.
    3) The achievement of smoke shield requires the thrust from the perpendicular surface and the upper surface which are orthogonally crossing.
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Review
  • Sayaka SUZUKI
    2017 Volume 67 Issue 1 Pages 49-55
    Published: 2017
    Released: July 13, 2018
    JOURNALS FREE ACCESS
    Experimental researches on structure ignitions by firebrands are reviewed in this paper. Over the years, different methods to make a proper firebrand were attempted. Starting from Usui's experiments by using burned woods distributed by a wind to roof tiles to many experiments with burned cribs placed on the roofs to the Firebrand Generator were introduced in this paper. In the past, most of researches was focused on only roofs, which have been known to be vulnerable to firebrands after 1976 Sakata Fire. Recently experiments with the Firebrand Generator have been investigating structures' vulnerabilities to firebrands as well as roofs'. This review hopefully leads to find mitigation or protection strategies in outdoor fires.
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