Study On Atomization Characteristics And Structure Optimization Of Internal Mixing Air-assisted Atomizing Nozzles

A large amount of particulate pollutants are produced in the production and transportation activities of mining,building materials,metal smelting and other industries.Workers working in high-concentration dust environment for a long time will cause serious threats to their health and safety.Therefore,it is very important to take effective measures to reduce the dust concentration in the production site.The device used for spray dust reduction is simple,and can be directly applied at the dust source point,and has good adaptability.Compared with the traditional pressure atomization nozzle,the internal mixing air-assisted atomizing nozzle has the characteristics of small water consumption,low water pressure,low clogging and high dust reduction efficiency.In this paper,numerical simulation method is used to study the flow field of the internal and near nozzle area of the internal mixing air-assisted atomizing nozzle and nozzle atomization characteristics;the effects of the number of intake holes,the diameter of the air cap outlet and the length of the mixing chamber on the atomization characteristics of the internal air-assisted atomizing nozzle were studied,and the following conclusions were drawn:First,when the air supply pressure is constant,as the nozzle water flow increases,the air velocity in the nozzle mixing chamber and the nozzle outlet decreases,and the droplet size increases overall;in the case of a constant water flow,as the air supply pressure increases,the average air velocity of the nozzle mixing chamber increases continuously,and the average particle size of the droplets is continuously reduced,but the decreasing trend is gradually slowed down.Second,with respect to the nozzles with two air intakes,the nozzle atomization effect of the four air intakes is significantly improved,with smaller droplet size and more droplets.Third,when the diameter of the air cap outlet is between 2.0 and 3.0 mm,the droplet size of the nozzle decreases continuously as the diameter of the outlet of the air cap increases.When the diameter of the air cap outlet continues to increase,the particle size of the droplets increases slightly,and the number of droplets also decreases.Overall,the nozzle atomization effect is best when the air cap outlet diameter is 3.0 mm.Fourth,the length of the nozzle mixing chamber can be appropriately increased to make the liquid phase and the gas phase sufficiently contact to improve the atomization effect.However,it should not be too long,which causes the gas-liquid two-phase discharge of the nozzle to be blocked,thereby affecting the atomization effect of the air.