Study On The Fire Caused By Flammable Gas Leakage And The Mechanics Of Its Spread

Supported by the National Basic Research Program of China (973), the fire caused by indoor fuel gas leakage was studied with the numerical simulation and experiment method. The laws of the process of leakage and combustion of the indoor fuel gas were gotten, which would direct the experience of fire prevention and suppression.In this paper, a simplified model was founded by abstract the reality of fire at first. Then, the process of leakage and combustion of the indoor fuel gas was numerical simulated by FLUENT6.1 software. Several cases in different conditions (igniting position, igniting time, leak speed and ventilate condition) had been simulated. At last, the experimental setup of fire combustion was founded based on the simplified model.A great deal of data, gotten from the numerical simulation, was analyzed in this paper, and several conclusions were found as following. The first, after ignited, the flame spreaded along the flammable zone before igniting. The second, the flame shape and color were determined by the concentration gradient of the place near the igniting position. If the concentration gradient was large, the flame would be flat, the color would be yellow and bright. While if the concentration gradient was small, the flame would be wide, and the color will be blue. The third, the part of the room upon the windowsill, was a hazard zone with high temperature and oxygen deficit. While the part of the room under the window was the last place the fire to reach, whose mean temperature was lower, and also was the first place the oxygen to reach. So it was a relatively safe place. In addition, the max turbulent flame speed is similar in these cases, which means turbulent influence on the indoor fire caused by gas leakage is less. The last, the spread of the flame was determined by both igniting position and the ventilation condition at the beginning of the combustion, and the combustion status after the fiashover was determined by the indoor mean concentration of the fuel gas. Verified by experiments, a conclusion was gained that the numerical simulation results agree well with the reality, which means to study the fire with the numerical simulation method was satisfying.