| With a large amount of dust produced in the process of coal mining,among them,the dust pollution problem is particularly serious,on the one hand,the long-term inhalation of such dust will greatly increase the risk of pneumoconiosis,on the other hand,reach a certain concentration of dust explosion easily but as a result of dust particle size small,ordinary droplets atomizing nozzle on its adsorption dust effect is not ideal.On the basis of summarizing the ultrasonic atomization mechanism,this paper designs an ultrasonic atomizing nozzle for the inclined wall micro-oscillation chamber based on the structure of the existing ultrasonic atomizing nozzle and the structural characteristics of the oscillation chamber and the inclined wall of the nozzle.Using numerical simulation software FLUENT,inside the nozzle under single-phase liquid working medium flow field numerical simulation analysis to explore the nozzle inlet pressure inclined wall Angle theta micro oscillation cavity diameter d 1 micro oscillation cavity depth and distribution of micro oscillation cavity shape parameters on the flow field inside the nozzle and the effects of micro oscillation cavity flow field,through the analysis of the results of numerical simulation,it is concluded that the structural parameters design scope:θ=52.5°-60°、l=0.9-1.2mm、d=1.8-2.4mm and micro oscillation cavity ladder type distribution.By using the acoustic module in FLUENT and based on the acoustic numerical method,the instantaneous sound pressure characteristics of the monitoring points of the resonator cavity and micro-oscillation cavity of the nozzle were investigated.It was found that the instantaneous sound pressure in the cavity changed with time as a sine curve,and the sound pressure level was 178Db.By comparing the acoustic pressure amplitudes in micro-oscillating cavities at different levels under different structural parameters,it is found that whenθ=52.5°、l=1.2mm、d=1.8mm,the acoustic pressure amplitudes in the cavities are the largest and the ultrasonic intensity is the highest.Comparing the variation of resonator sound pressure level under different inlet pressures,it is found that when the inlet pressure is 6MPa,the atomization efficiency of the nozzle is the highest.Based on the results of the entrance of the single-phase liquid propellant gas nozzle,increased the coaxial gas inlet,designed two kinds of gas liquid two phase atomization nozzle,through the comparative analysis of two kinds of nozzle flow field distribution,it is concluded that the flow field in the nozzle type I(perturbation model is more apparent in type I nozzle,analysis found that the change of the gas phase,inside the nozzle inlet gas rate is higher,the inlet pressure,the greater the nozzle in the gas phase volume fraction is higher,the unit time into and out of the more micro oscillation cavity fluid,fluid velocity,the higher of the nozzle exit Therefore,when the air inlet holdup rate is 20%-30%and the air inlet pressure is 4-5MPa the disturbance effect of air relative to the fluid in the nozzle is optimal. |
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