To reveal the fire characteristics such as mass burning rate, flame height and puffing frequency of subsisting multiple fire sources, experiments were conducted for two small pool fires arranged in three dimensions. Two different kind of fuels, n-heptane (luminous flame) and methanol (non-luminous flame) were employed for test fuels. Each pan diameter is 49 mm, and the two pans are arranged in horizontal distance between center of each pan ranged from 50 to 150 mm, in vertical distance between each surface ranged from 0 to 600 mm. As a result, mass burning rates for both of pans are lager than that of a single pool fire, especially the burning rate for upper pan is remarkable increases compared with that for lower pan. The external radiation heat and induced air flow by multiple flames contributes to increase of the burning rate for multiple pool fires. The flame height and the puffing frequency of multiple pool fires depend on the separation distance of each pan both in horizontal direction and vertical direction. The flame height for upper pan is smaller than that for lower pan, contrary the puffing frequency of upper flame is higher than that of lower flame.
A physics-based urban fire spread model formerly developed by the authors was refined by considering fire fighting activities of community residents. The model is based upon the zone concept in which properties of gas inside compartment, component of buildings in urban area, is assumed as uniform. Mitigation of fire hazard due to water application is evaluated by incorporating following consequences of water evaporation into the conservation equations of compartment gas : (A) cooling of compartment gas ; (B) dilution of compartment gas ; (C) cooling and wetting of fuel surface. Initiation time of water application, which is a predominant factor of success and failure of fire suppression, is evaluated as a sum of detection time of fire , assembling time of residents, and preparation time for equipment use. The proposed model was applied to simulate fire spread behaviors in a hypothetical urban area where 121 buildings of identical configuration were aligned in a regular pattern. Case studies were carried out in order to investigate effects of anticipated critical parameters such as fire detection time, and number of water supply port.
Smoke movement tests conducted at an side-platforms subway station actually in service in Tokyo in October 2003 using 320-480kW methanol pool fires as fuel are reported. The fire safety design of the station is essentially based on the currently effective underground station design guide, and operation of the existing smoke extraction system and the fire shutters in the stairway between the platform and the concourse was the major experimental parameters. Distribution of temperature, velocity and static pressure throughout the platforms, the tunnel and the concourse were measured. In comparison with the center platform station reported earlier by the same authors(JAFSE Bulletin Vol.56, No.2), there has been general anticipation that smoke movement and threat to life safety in side-platforms station can be different in 1) the larger volume on the platform level and 2) the possible delay of the approach of smoke and detection of fire on the opposite-side platform. In addition to the significant influence of the operation of fire shutters as also seen on the center-platform stations, the test results reveal generally wider spread of smoke toward the ends of the platforms. Performance of the smoke extraction was also found to be significantly affected by the operation of the shutters and is less effective than in center-platform station probably for the larger volume of the platform level.
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