Structure Design And Numerical Optimization Analysis Of Piezoelectric Ultrasonic Atomizing Nozzle For Mine Dustfall

With the acceleration of industrialization,coal and other mineral resources are rapidly consumed,and the disadvantages of traditional dust removal methods are increasingly obvious,resulting in a rapid rise in dust concentration.This not only has a serious harm to the health of miners,but also has certain safety hazards,which is easy to cause dust explosion.Especially for respirable dust,they have a small particle size and can enter the human alveolar through the respiratory tract,thus causing pneumoconiosis.Due to the small particle size of the respirable dust,it is difficult to effectively capture the dust by ordinary water mist and can not achieve good dedusting effect.The piezoelectric ultrasonic atomizing nozzle utilizes the converse piezoelectric effect of the piezoelectric material to generate an effective amplitude,and breaks the liquid into fine droplets,which can effectively capture and settle the respirable dust.Therefore the method has remarkable dust removal effect.In this paper,through the analysis and research of ultrasonic atomization technology and piezoelectric material characteristics,combined withone-dimensional elastic vibration theory,the mechanical vibration structure of ultrasonic atomizing nozzle is theoretically designed,and finite element simulation analysis is carried out.In addition,by designing the fluid passage of the nozzle,the structural design of the nozzle is organically combined with the flow field,and the fluid calculation analysis software is used to simulate the external flow field of the fluid.A piezoelectric ultrasonic atomizing nozzle with a resonant frequency of20 kHz is designed.The nozzle consists of a sandwich ultrasonic transducer,a stepped horn with a circular arc transition and an atomizing disk.Through the theoretical calculation,the specific dimensions of each part of the nozzle are obtained.The modal analysis and harmonic response analysis are carried out using finite element analysis software,and compared with the theoretical calculation.The finite element analysis shows that the resonant frequency of the system is 20480 Hz,which is 2.40% different from the theoretical calculation.When the orthogonal test is used to obtain a transition arc radius of3 mm,an atomization disk diameter of 13 mm and a thickness of 3 mm,the resonance frequency obtains an optimum value of 20153 Hz.The harmonic response analysis shows that the nozzle reaches a peak amplitude of 4.78 ?m at the front end surface of the atomizing disk,which can effectively break the continuous liquid into droplets.The working stress reaches a maximum value of 12.01 MPa at the arc transition of the horn.The fluid numerical analysis software was used to simulate the externalflow field of the single-phase nozzle jet,and the radial turbulent kinetic energy,velocity and dynamic pressure at different inlet pressures and nozzle outlets were studied.According to the analysis,the jet velocity,dynamic pressure and turbulent energy of the nozzle in the air satisfy the law of increasing first and then decreasing,and the speed takes the maximum at the exit of the nozzle.Under the action of air resistance,the attenuation is faster at the beginning,and later the attenuation speed is gradually reduced,and there is a phenomenon of entraining air around the jet,and the entire injection process is completed together with the air.Two inlet and outlet nozzles of water and gas were obtained by adding inlet passages at the periphery of single-phase water nozzles,and numerical simulation analysis was carried out on the jet characteristics of the external flow field.By extracting the parameters of radial turbulent kinetic energy,velocity and dynamic pressure at different flow directions of the nozzle outlet,the variation law of the jet of water and gas two-phase nozzle is obtained.When compared with the single-phase water jet,it is found that the water and gas two-phase nozzle can slow down the speed and the dynamic pressure attenuation speed,the turbulent energy is larger,the disturbance to the surrounding air is stronger,and the jet flow ability is stronger.