Study on Inert Gas-Form Extinction Method applied for Three-dimensional Arranged Fire

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To reveal the fire characteristics subsisting multiple fire sources and fire extinguishing by inert gas-form, experiments were conducted for two small pool fires arranged in three dimensions. Two different kinds of fuels, n-heptane (luminous flame) and methanol (non-luminous flame) were employed for test fuels. 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. To clarify the effects of external radiation and induced flow on burning rate for multiple fire sources, the model calculations considered the effects of radiative heat fluxes and change of flow fields. When the fires are separated, the increases of burning rate depend on the radiative heat flux emitted from the other fire. When the fire sources are arranged in three dimensions, we found that not only the effect of the external radiation but the effect of the flow field is important. When the pan diameter is larger, the effect of radiative heat flux is larger and the influence of flow fields is relatively small. From the characteristic of the three-dimensional fire obtained by this study, supplying a strong and high fluidity form to the upper fire efficiently is required. To make a strong and high fluidity form, the diameter of a form was changed and the fire-extinguishing experiment was conducted. By setting the diameter of a form to about 1mm, the fluidity and the intensity of a form were able to increase, and a three-dimensional fire was able to effectively extinguish.