| Due to the particularity of highway tunnel engineering in structure and ventilation, etc. once fire in the highway tunnel, the traditional water spray and gas fire-extinguishing technology has its limitation in the application, and causes great difficulties to evacuate and rescue. It is of great significance for strengthening the tunnel project fire safety to Study on the effectiveness of water mist fire extinguishing system and parameters of operation system. This paper uses FDS to set up the fire model of4MW highway tunnel. Start the water mist for90s polycomponent water, by analysising the parameters of the heat release rate, temperature of fuel surface and fire plume and distribution CO concentration or velocity. And then find the mechanism and effectiveness of coupling highway Mechanical ventilation with water mist.First of all, the author contrast result of the different position of tunnel water mist sprayer and fire,and draw the conclusion that it is the most efficient When the water mist sprayer in directly of the fire, it will become worse with the horizontal distance between the sprayer and the fire. By the method of increasing the injection angle of the sprayer and expanding protection range, we can extinguish the fire that far away from the sprayer.After analyzing the effect of Comprehensive role of water mist and Mechanical ventilation, The author draw the conclusion that the best is Mechanical ventilation and water mist work together. In this model the water mist mainly performs the role of cooling.By analyzing the effect of Joint action between water mist and longitudinal ventilation in highway tunnel, the author draw the conclusion that activating the longitudinal ventilation earlier than the water mist is better, and effect of the restraining smoke of longitudinal ventilation is obvious; in this model water mist mainly perform the role of cooling to the Fire plume.By analyzing the effect of corporate action of longitudinal ventilation started after 60s, top smoke and water mist started after90s, the author draw the conclusion that top smoke and air supplied in the upper of the combustion source, the extinguishment mechanism of the coupling system is mainly the cooling the fire plume; then in the model of top exhaust fan and to air supplied by the longitudinal fan on both sides of the tunnel, the extinguishment mechanism of the water mist is mainly of the cooling the fuel surface... |
