水平天井面を軸対称に拡大する火災初期の煙先端部位置の近似解析解

Abstract

The approximate analytical solution of the location of smoke front below horizontal ceiling at early time in fire is derived by the handling as the axi-symmetric problem. At first the approximate analytical solution of the average temperature of smoke layer is derived in assuming that the progress velocity of smoke front is proportional to 1/2 power of time based on the mass preservation. Then the integral equation to predict the location of smoke front is derived in this smoke average temperature. As this equation is not able to solve analytically, an approximate analytical equation is derived by approximation of integrand and being subject to temperature less exceeding initial inflow temperature. Particularly, in case of the treatment of center sprang out, the location of smoke front is proportional to 1/2 power at early time then to 3/4 power at time. The prediction is compared to the experimental data. It is shown that the location of smoke front is predicted by the approximate analytical solution.