Study On The Interaction Between Water Mist And Fire

All kinds of poisonous and harmful gases, corrosive gas, smoke particles, etc. in fire smoke has great destruction to human life, property safety and environment. So it is imperative to look for effective methods of preventing fire and fire smoke. Water mist are considered to be the ideal substitute for halon extinguisher with characteristics that friendly to environment, putting out the fire quickly, lower water consumption, etc. so that it receives extensive attention in the field of academia and fire technology application. However, large-scale application of water mist is limited by a certain due to the water mist fire extinguishing mechanism is relatively complex.Two aspects that fine water mist fire extinguishing leading mechanism and the interaction between water mist and smoke have been considered. PIV, Opacity Tester, infrared thermograph has been used in our experiments. Temperature and humidity, concentration of gas, wind velocity have been also tested. The heat transfer process of the interaction between water mist and fire plume and the exchange process about energy and mass have been analyzed with the measuring results. The research findings have a certain guiding significance for application of water mist fire extinguishing technology.The experiment model about water mist extinguishing alcohol fire was built in Underground Engineering Laboratory of Northeastern University first. The characteristic parameters of water mist such as spray cone-angle, mist flux, velocity distribution etc. were tested with PIV. Velocity distribution under different pressure of water mist has been studied in experiments. Then the function relationship about the pressure of water mist and the distance from nozzle have been built by fitting the data, and the velocity of droplets would be predicted under different pressure and different distance.Critical thrust ratio has been studied by the mist distribution above the pan and the change of temperature in the fire scene, based on the research on the characteristics of mist.This paper draws the critical temperature of fuel surface and critical thrust ratio of different mechanisms from two aspects about flame cooling and fuel surface cooling.Another experiment about water mist extinguishing diesel pool fire was conducted. The regularity of the spread of fire smoke effected by coupling of top smoke discharging and water mist was analyzed systematically, based on testing the temperature of flame, visibility, concentration of gases. What’s more, the effect to diesel pool fire burning by coupling system under different opening time was discussed too. The researches show that it is bad for evacuation and rescue when opening water mist and top smoke discharging in fire fully-developed stage. And visibility will improve effectively by coupling effect of top smoke discharging and water mist.