Study On Smoke Movement And Management Under Surrounding Winds

Smoke is the most dangerous factor to personnel in building fires. Smoke management is essential for a fire protection system of a building. However, smoke spread is easy to be affected by surrounding conditions, such as winds. Theoretical analysis, numerical simulations and model tests are carried out to study smoke movement and control in this dissertation. Achievements of this study are listed as the following:1. A mathematic model for predicting mass flow rate of plume affected by horizontal wind is proposed. Influence of surrounding wind on mass flow rate of plume is discussed and dimensional analysis is adopted to obtain the expression of mass flow rate of tilted plume. The expression can be referred for calculating smoke generation in a fire.2. A testing platform with surrouding wind is set up and series of small-scale experiments on natural exhaust under different velocities of wind are carried out. The results can be referred for design of smoke management system and assess the performance of natural exhaust systems under surrounding winds.3. Overall pressure coefficient is proposed to evaluate the influence of surrounding wind on natural smoke exhaust. A critical velocity of invalidation at which the natural exhaust will lose its function is reduced and is found to be proportional to -1/2 power of the absolute value of overall pressure coeffiecient.4. A simplified two-layer zone model is developed to simulate smoke filling in a compartment with natural smoke exhaust under surrounding wind. Experimental verification shows that the model is precise enough for predicting the process of natural smoke exhaust under surrounding wind. The model is recommended for the authority to use as a tool in evaluating the performance of static smoke exhaust system.The conditions of actual fire vary much from each other. Therefore, configuration of smoke management system of a building should accord with the demand of the building. According to this point, the work of this thesis is helpful to design of smoke management system of a building for its model and data reference.