| Spray dust mechanism is the use of high-speed movement of the floating mist particles to intercept, capture, and finally condensed dust particles in the air. In the coal mine, the most damaging is the≤5μm breathing dust, so we need to take effective measures to catching such dust. There are a number of discovery from the analysis to the main factors that affecting catching dust :When mist particle velocity and water droplet diameter is constant, the efficiency of dust reducing increases with the dust particle size. It will tend to be constant when it reach a certain value .Large drops can effectively catch large particles of dust.The best range of spray particle is 60μm-160μm for 1μm, 2μm, 3μm dust particle. Jet speed must be greater than 35m/sec to make the breathing dust more than 50% efficiency, The nozzle design is the key at dust reducing in the spray system, because the atomization performance has a direct impact on the effect of dust. Increasing injection flow rate and injection pressure, have some limitations. Therefore, taking the spray nozzle design into considerations, it is imperative to improve the effectiveness of the method. Integrating the harsh coal mine work environment, reliability design and simple manufacture and other factors, we can design a kind of nozzle without the swirl core, but can produce better results spray. Not using swirl core, fluid in nozzle is still capable of producing relatively large rotary movement, which will allow fluid spray nozzle. After spraying, under the influence of centrifugal force, it can result in better atomization effect. Therefore, a certain angle is required when fluid flow into the nozzle, after fluid into the nozzle, this will produce horizontal speed, this will lead to a certain degree of rotation. This kind of nozzle was designed according to this idea.Making use of CFD(Computational Fluid Dynamics)simulates liquid's flow for studying flow state inside the nozzle in the spray nozzle. Obtained through simulation analysis:Nozzle cavity is constant, spray spread angle increases with the diameter. The reason is that liquid can produce the swirl intensity inside the large-diameter nozzle. Comparison of 1.0mm, 1.2mm, 1.5mm, 1.75mm diameter nozzle, the swirl speed increase in turn;when nozzle diameter is certain, spray angle increase with the internal diameter proliferation;the cyclone effect is better at the swirl angle of 30 degrees when diameter and internal diameter nozzle are certain;The cent needle has smaller affect to disturbance and viscous resistant with the central regulator needle farther away from the nozzle exit. The internal speed increases continuously. When the distance increases to a certain value, the needle is negligible role. Fluid can produce strongest internal swirl when the needle is far from the nozzle exit.To get a better effect of dust,Nozzle design should take into account a number of matches between their own. Internal diameter nozzle and nozzle exit diameter should to be a certain degree of matching relations. For the diameter d0 = 1-1.5mm nozzle, nozzle internal diameter is appropriate to take D = 6mm;d0 = 1.75-2.5mm, is suitable to take D = 6.5mm.Taking the length L jet of nozzle between the value of 0.5-1 times diameter, large diameter angle can be obtained. In the range that the system allows, the increasing of water pressure can increase angle of export.
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