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Volume 44 (1996)
- Issue 1+2 Pages 1-
Volume 44, Issue 1+2
Displaying 1-4 of 4 articles from this issue
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Paper
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Tohru UETAKE, Manabu WATANABE, Matunori NARA1996 Volume 44 Issue 1+2 Pages 1-7
Published: 1996
Released on J-STAGE: September 16, 2011
JOURNAL FREE ACCESSThe flowout coefficients of the crowd movement through doors and corridors that we are using in the fire safety design of buildings were measured over 30 years ago. We measured the flowout coefficients of getting commuters off the trains and down the stair at the terminal station and leaving visitors from the theaters and movie theaters by use of the video tape recorder to get the recent data. The following results which measured at the passage through the door and the landing (at the entrance of stairs) were obtained: (1) the coefficient of the passing people were increased in proportion to the increase of the number of people who were waiting to pass: (2) the flowout coefficient greater than that of the conventional value: (3) the number of passing people didn't increase in proportion to the door and landing width, but step-wise under the condition of less than 2 meters in the width: (4) the flowout efficient at both the door and the landing was increased in proportion to the accumulating people in the queue, as increase the people, the flowout coefficient was saturated.View full abstractDownload PDF (562K) -
Masataro SUZUKI, Ritsu DOBASHI, Toshisuke HIRANO1996 Volume 44 Issue 1+2 Pages 9-14
Published: 1996
Released on J-STAGE: September 16, 2011
JOURNAL FREE ACCESSTo explore the flame spread mechanisms over cellulosic solid sheets, the temperature profiles in the vicinity of spreading flames over paper sheets from 1.0 to 6.3-mm thick have been examined by using fine-wire thermocouples.
Measured isotherms indicate that the location of the leading flame edge in spreading direction is almost the same for sample sheets from 1.0 to 5.8 mm-thick, and shifts downstream when the sample thickness is 6.3 mm. As reported in the previous paper, the flame cannot spread stably over sample sheets thicker than 7.5 mm. The stand-off distance of the flame at a given station downstream of the leading edge becomes small as the sample thickness increases. However, the maximum value of heat flux to the solid surface from the flame decreases and its location shifts downstream as the thickness increases. As a result, most of heat from the flame to the unburned material transfers through the char layer formed on the sheet. This layer is supposed to be a cause for increasing radiative heat loss since the temperature on its surface becomes higher than the pyrolysis temperature. These results imply heat flux to the preheating region decreases as the paper thickness increases. This decrease of heat flux may cause the stop of flame spread along a thick sample.View full abstractDownload PDF (545K) -
Kenjiro YASUNO, Yoshiro NAMBA, Mitiaki BOIKE1996 Volume 44 Issue 1+2 Pages 15-23
Published: 1996
Released on J-STAGE: September 16, 2011
JOURNAL FREE ACCESSMany fires occurred simultaneously in the Kobe earthquake and the several became city area fires. Thereupon, the fire spread condition were analyzed about large-scale fires that have burn-out area over about 10,000 m2 with this research. We used the fire data that were obtained by Fire Department of Kobe city and Tokyo Fire Department at the present. It is a future research theme about the fire spread condition which fire fighting water for suppressing is considered, because it is not sufficient data regarding fire fighting water for suppressing at the time of a fire. We researched a fire spread formula that considered burn-out area in this paper. The result that was obtained is as follows.
1) A fire spread speed formula that considered the complete collapse rate of houses at the time of an earthquake was indicated in eq. (7). Coefficient of correlation between this eq. (7) and the real fire data is r=0.984. This is agreeing fairly well.
2) a1 is about from 0.0114 to 0.0626 in the case that G ≒ 10,000∼120,000 m2, complete collapse rate D ≒ 30∼70% and average wind velocity v ≒ 1.3 m/sec as shown in Table 4 and Table 7. This is about 1/13∼1/7 in comparison with a1=0.143∼0.460 of the experiment result of real house group of Saganoseki (G ≒ 150∼804 m2, D=0, v ≒ 1.8 m/s). One of this cause is considered that the houses were completely destroyed about the rate 30∼70%.View full abstractDownload PDF (621K) -
Tomohiro NARUSE, Shinichi SUGAHARA1996 Volume 44 Issue 1+2 Pages 25-37
Published: 1996
Released on J-STAGE: September 16, 2011
JOURNAL FREE ACCESSA lot of studies on fire plumes formed above fire sources have been carried out in the field of building fire analyses. There are two methods to define the boundaries of continuous, intermittent and plume regions of turbulent diffusion flames. One is to be decided from flame height. And the other is to be decided from the properties of fire plumes on the basis of the classical theory on the point-source plumes. The relationship between them had been ambiguous, and we proposed the following models of virtual source locations resulted from the past experimental works [15-18]:
z0 = (γ − α2/5C')Q＊2/5D (Q＊ ≧ 1),
z0 = γQ＊2/3D − α2/3C'Q＊2/5D (0.1 < Q＊ < 1)
In order to ensure these models, several experiments were performed by using 0.14 m or 0.2 m square burner with LPG or LNG fuels. Flame heights were recorded by video tape recorder, and the centerline temperatures and velocities were recorded for 5 minutes at 5 seconds interval in a steady state.
As the results, the flame heights were formulated as Lf=γQ＊nD, where n=2/5 for Q＊ ≧ 1, and n=2/3 for 0.4 < Q＊ < 1. And γ equals 3.30 for the mean heights, 4.40 for the boundary height between intermittent flame region and plume region, and 2.10 for the boundary height between flame region and intermittent flame region for calculating z0. According to these results, excess temperatures and velocities were plotted above along the central axis of fire plumes. It was found that the boundaries decided both from flame heights and from excess temperatures had been in agreement with each other.View full abstractDownload PDF (927K)
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