Numerical Simulation Of Building Fire Single Room-Zone Model

New programs calculating absorption coefficient of radiation for hot gas and simulating the effect of suppression of water spray on fire are applied to the one-room Zone model FIRST in the dissertation. Fire in a building room installing fire detectors and water sprinkler below the ceiling is simulated. The fuel is PUF objects whose heat of combustion are 2.87×107J/kg and combustion efficiency are 0.65. The radius of object 1# is 0.860m and object 2#, 0.344m .The thickness of objects is 0.1m for both.Radiation of the hot layer is very important in fire simulation, thus the radiation coefficient is vital. Since radiation power of steam and CO2 in the hot layer contributes to the values of absorption and radiation coefficients, one of the aims of this paper is to develop new reliable and useful programs concerning radiation capability of steam and CO2. Compared with the original model, the new one has such virtues:1.The applicable range is 273KK which is wider than that of the original one (300K2000K).2. Radiation coefficients of steam and CO2 are given as stepped functions. Users can select any seemly part without going through the whole one.Once fire happened and developed to a certain grade such as temperature, depth or density of the hot gas layer getting to the active value of the detector, the sprinklers would start to work. Introducing virtual spray coefficient adjusts the suppression effective errors raised when water spray area is not equal to the real sprayed surface area of the object. Water spray flows down through the fire plume, when it reaches the surface of objects water is heated and vaporized. This causes three results: the vapor is taken to the hot gas layer by the gas plume and then changed the mass, energy and species' density of the hot gas layer, etc; the surroundings of the objects is cooled; the chemical reaction rule of combustion is changed to be more complex. Choose a series of water spray flow rates and virtual spray coefficients separately for simulation, the conclusions are:1.Object 2# does not get fire during the period of simulation because of early suppression2. There are both a critical and a maximum value of flow rates separately for a certain fire. In this research, the values are 0.0524kg/s and 0.2kg/s. If the water flowrate is smaller than the critical one, fire is sustained with an increasing heat release rate. If the flow rate is larger than the maximum, the suppression effect is similar to the one under the maximum flow rate.3. With the same water flow rate, the values of virtual spray coefficients can influence the suppression effect directly. The smaller the virtual coefficient is, the worse the effect is,the higher is the heat release rate correspondingly, etc.4. Destruction of fire would be lower if water sprinklers could work in time and properly.