Study On Atomization Characteristics Of Supersonic Siphon Air Atomizer And Its Field Application

The spray dust reduction technology is widely used in the prevention and control of underground dust.The traditional spray dust reduction uses the water mist sprayed by the internal mixing air atomizing nozzle and the X swirl atomizing nozzle.The droplet size is large and the speed is slow.Particulate dust has a good settling effect,but the collection efficiency of respiratory dust with small particle size is not good.The water mist droplets sprayed by the supersonic siphon air atomizing nozzle developed by this team have small particle size and fast speed,and have a strong ability to capture various types of dust.It is a new and efficient atomization dust reduction technology.The research on the distribution of the droplet field still needs to be in-depth.This paper focuses on the experimental research on the atomization mechanism,droplet size,droplet velocity and dust reduction efficiency of supersonic siphon air atomizing nozzles.Firstly,the atomization mechanism is studied,and the atomization mechanism is analyzed by the linear instability theory of fluid mechanics.The atomization method,it is theoretically clear that the atomization method of the supersonic siphon air atomizing nozzle has the advantages of small droplet particle size and fast speed.Based on the theory of spray dust suppression,the mechanism of dust capture by fog droplets is studied,and it is confirmed that the particle size of droplets and the speed of droplets are important factors affecting the effect of dust capture.Secondly,experimental study on the atomization characteristics of supersonic siphon air atomizing nozzle.An experimental system for testing the atomization characteristics of nozzles was built,and a laser particle size instrument was used to measure the droplet size,and a threedimensional particle image velocimeter was used to measure the droplet velocity.It was learned that:(1)The droplet size experiment studied the influence of different factors on the atomization performance and compared the atomization characteristics of different types of nozzles.The results show that the droplets with different distances from the nozzle exit,with the increase of the distance,the collision polymerization after crushing increases from strong to weak.As the air supply pressure increases,the droplet size of the supersonic siphon air atomizing nozzle gradually decreases,and the minimum SMD(average particle size)within the measured distance is 20.48μm.Under different air supply pressures,the particle sizes of the droplets with different distances from the nozzle outlet are basically the same as the distance increases.When the air supply pressure in the effective range is 0.1～0.5MPa,the SMD is only 20.48～29.15μm.In the comparison experiment,the supersonic siphon air atomizing nozzle is 53.5%～74.0%smaller than the internal mixing air atomizing nozzle and the X-swirl pressure nozzle SMD.(2)Droplet velocity the effect of different air supply pressures on the droplet velocity in the fog field was studied in the area of 30～60cm and 60～90cm from the nozzle outlet.The results show that in the area of 30～60cm from the nozzle outlet,the greater the air supply pressure,the faster the overall droplet velocity in the fog field,and the smaller the attenuation of the droplet axial velocity 30.49% weakened to 12.88%;in the area of 60～90cm from the nozzle outlet,the greater the air supply pressure,the faster the overall droplet velocity in the fog field,and the greater the attenuation of the droplet axial velocity.As the air supply pressure increases,the decay rate increased from 14.95% to 29.47%.The research analysis shows that the droplet velocity attenuation degree is mainly related to its own velocity and droplet concentration in the fog field.Through the spray dust reduction experiments of supersonic siphon air atomizing nozzles on the total dust and exhaled dust of pulverized coal and rock powder at different water supply pressures,it is known that when the air supply pressure is 0.1～0.5MPa,the total dust of pulverized coal is reduced.The dust removal efficiency is 75.67%～91.46%,the dust removal efficiency of coal dust is 73.82%～90.77%;the dust removal efficiency of rock dust is75.41%～91.15%,and the dust removal efficiency of rock dust is 72.8%～89.64%.Last,after analyzing the on-site dust pollution of the fully mechanized excavation working face of Hanjiawa Coal Mine,a supersonic siphon spray dust removal system was designed,and the dust reduction effect of the installed fully mechanized excavator cutting head with full coverage spray and dust-proof purification fog curtain was investigated.At a distance of 10 m from the excavation end,the dust reduction efficiency of total dust and exhaled dust reached90.05% and 87.33%,which were 55.84% and 63.82% higher than the previous dust reduction measures,respectively.At the distance of 20～50m from the excavation end,the total dust and exhalation dust reduction efficiency reaches 96% and 92%,which are 73.62%～86.89% and72.13%～80.95% higher than that of the original external spray 80.95%.