Research On Forecasting Properties Of Fire Smoke Flow In Multilayer And Multifunctional Building

The forecasting system of the properties of fire smoke flow in building has been becoming increasingly mature with so many precursors'efforts. After solving the problem of stringency, the number of nodes will arrive almost one hundred. The optimized ventilation system and the combine with evacuating system basically accomplished the finally packing before it enters the market.The smoke flow software is comparatively mature, but it is only a single kind of Net-work model, the hypothesis which the model based on will greatly restrict its application. The primary hypothesis is seeing the total room as a node and the instant mixing of smoke and air. If the volumes of all rooms almost the same, this error made by this hypothesis can be neglected, but the modern building tend to multilayer and multifunctional, the volumes inside the building are greatly distinct to each other, such as that some multifunctional room and auditoria have a more lager volume than guest room, under this circumstance, the foregoing hypothesis will incorrect, the calculation result will be inauthentic, then, the properties of the fire smoke flow can not be reflected. Aiming at this instance, when simulating the fire in complicated volume, the burning room and some special volume can simulate by field model, and then can give the parameter's distributing in space and time. The rooms adjoining can be simulated by Zone-model, constructing the equation given condition of environment parameter and the diversification along upright aspect. Finally, the rooms far away from the burning room, can be acted as a network node, using Network-model. The result of different models can be used as boundary condition of others when calculating, which can make full use of every model. It can give all the critical parameters and avoiding the disadvantage of high expense when using Field-model singly, the practicability will widened mostly. Through this we can build the connecting between field, zone and network model, then empolder the circulating environment of the composited model.For the composite simulation with field-model and network-model, we can get the pressure distributing through beforehand simulation, then divided the hatch into small areas which will be propitious to calculation such as the aclinic long rectangle. Through calculating the pressure difference then adding them together, the total mass flow and energy flow will be gained. Simulation example used the FLUENT software, it simulated the burning room firstly, researching the parameters'distributing. It can get the velocity and temperature in each node in the hatch of burning room, then the properties of the burning-hatch can be used as the boundary condition in network simulation the next step. The result of the network also provide boundary condition for the following field simulation in special room, and research the parameters'distributing in room with big volume. Finally, through an experiment on a tower building, validating its effect when simulating the multilayer building with different volume. The conclusion is that, the complicated simulation is feasible abstractly when simulating the building fire, the result is accord to the principle of smoke flow, the complicated model has a broad future.Heat-convection is one of the most important heat-spread modes, but it can't be confirmed in fire. The article analyze using the FLUENT to calculating all the process in fire and all the process of heat-transfer, then it can get the temperature distributing in the whole room and the temperature everywhere, and finally can get the local heat-coefficient with the heat-convection equation.