Design And Research On Atomizing Nozzle Of Water Mist Fire Extinguishing System

Water mist fire extinguishing technology by virtue of its environmental protection and pollution-free,sustainable development,efficient,water-saving,small damage to the protection of the target and other advantages in fire prevention and protection has been widely used.However,as the core component of the water mist fire extinguishing system,the atomization effect of the water mist nozzle is lower than the expected standard and cannot fully meet the requirements of the technical specifications for water mist fire extinguishing in China,which limits the development of the water mist fire extinguishing system in my country.Therefore,the research object of this paper selects the fine water mist nozzle,through its theoretical analysis,design calculation,simulation,analysis and research on the fine water mist nozzle,for the design of fine water mist nozzle and engineering installation applications,etc.provides theoretical support.The research content of this paper consists of the following aspects.（1）Through the introduction of different fire-extinguishing technologies and the comparative analysis of the advantages of water-mist fire-extinguishing technology,the research status of water-mist fire-extinguishing systems and water-mist nozzles is summarized.And then draw the meaning and purpose of the subject.（2）This paper introduces and classifies the water mist fire extinguishing system and atomizing nozzles,and introduces the atomization mechanism of the water mist,including the primary atomization that occurs just after leaving the nozzle and the secondary atomization that occurs with the air medium under the nozzle.The atomization mechanism lays a theoretical foundation for the subsequent analysis of the fine water mist nozzle.（3）The characteristic indexes of the atomization quality of fine water mist are introduced,including atomization particle size,spray cone angle,flow coefficient,and droplet distribution characteristics,and the factors affecting the atomization quality are summarized.This provides important guiding parameters for the design of water mist nozzles.（4）Through the design theoretical formula of the nozzle,the relevant parameters of the water mist nozzle structure are obtained by design and calculation,the three-dimensional modeling of the water mist nozzle is carried out by the Solidworks 3D software,and the designed nozzle is studied by the simulation software Fluent.The relevant parameters that affect the atomization performance of the nozzle are deeply explored.As the pressure increases,the nozzle flow rate increases with the increase of the pressure,but the growth rate of the flow rate slows down with the increase of the nozzle pressure.The flow rate increases with the nozzle diameter;the greater the spray pressure,the greater the droplet exit velocity and the smaller the droplet size.（5）Pyrosim software was used to establish a numerical simulation of the effect of water mist on indoor room fires,and the effects of different particle sizes,different flow rates and different spray speeds on fire suppression by water mist were analyzed.The finer water mist with smaller droplet size has better extinguishing performance.The fire extinguishing time of the water mist increases with the increase of the droplet size;the fire extinguishing time of the water mist decreases with the increase of the flow rate;the greater the speed of the water mist,the better the fire extinguishing ability.