The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this study.The results were defined by Reynolds number,which focuses on the breakup of liquid film,droplet size,velocity,and liq...The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this study.The results were defined by Reynolds number,which focuses on the breakup of liquid film,droplet size,velocity,and liquid volume flux under different Reynolds numbers at the near-field spray.The spray structure was visualized using a high-speed camera,and the characteristics of droplets were measured using a Phase Doppler Anemometer(PDA)in both the radial and axial directions.The tests were carried out at varying spray pressures(0.2 to 1.0 MPa),corresponding to different Reynolds numbers(5369 to 12006).It was found that when the Reynolds number rises,the liquid became more unstable after leaving the nozzle,causing the liquid film to break up faster.According to the measurements of PDA,the coalescence of droplets increased due to the centrifugal effect.What’s more,the velocity of the droplets fluctuates significantly in the radial direction,and the droplets with a smaller particle size had a higher average velocity.From the perspective of liquid distribution,the increase in Reynolds number caused the spray liquid to move in the radial direction gradually.In contrast,the liquid volume distribution changed in the radial direction more obviously than in the axial direction,growing to the maximum along the radial direction and gradually reducing.It can provide a reference for selecting operating parameters for actual agricultural spray operations and the design of electrostatic nozzles through the research on breakup and droplet characteristics.展开更多
密封钢丝绳生产的关键是Z形钢丝的生产,整体模拉拔Z形钢丝的关键是各道次拉丝模的孔型设计,应保证腰部两侧最大压下量处的模具工作锥半角不大于6°。采用12.5 mm 82B盘条经2道次圆形模和7道次异型模拉拔,选择70%~77%的总压缩率,...密封钢丝绳生产的关键是Z形钢丝的生产,整体模拉拔Z形钢丝的关键是各道次拉丝模的孔型设计,应保证腰部两侧最大压下量处的模具工作锥半角不大于6°。采用12.5 mm 82B盘条经2道次圆形模和7道次异型模拉拔,选择70%~77%的总压缩率,以及适当的道次压缩率,成功生产了1 770 MPa级Z6光面钢丝和1 670 MPa级Z6镀锌钢丝。提出Z形钢丝生产中应注意的问题,并对整体模与辊模拉拔进行对比,指出整体模拉拔更适合小批量生产。展开更多
基金support provided by National Natural Science Foundation of China(Grant No.31971797)National Natural Science Foundation of China(Grant No.32271997)+3 种基金China Agriculture Research System of MOF and MARA(CARS-26)General Program of Guang-dong Natural Science Foundation(2021A1515010923)Guangdong Provincial Special Fund For Modern Agriculture Industry Technology Innovation Teams(Grant No.2023KJ108)Key-Area Research and Development Program of Guangdong Province(2023B 0202090001).
文摘The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this study.The results were defined by Reynolds number,which focuses on the breakup of liquid film,droplet size,velocity,and liquid volume flux under different Reynolds numbers at the near-field spray.The spray structure was visualized using a high-speed camera,and the characteristics of droplets were measured using a Phase Doppler Anemometer(PDA)in both the radial and axial directions.The tests were carried out at varying spray pressures(0.2 to 1.0 MPa),corresponding to different Reynolds numbers(5369 to 12006).It was found that when the Reynolds number rises,the liquid became more unstable after leaving the nozzle,causing the liquid film to break up faster.According to the measurements of PDA,the coalescence of droplets increased due to the centrifugal effect.What’s more,the velocity of the droplets fluctuates significantly in the radial direction,and the droplets with a smaller particle size had a higher average velocity.From the perspective of liquid distribution,the increase in Reynolds number caused the spray liquid to move in the radial direction gradually.In contrast,the liquid volume distribution changed in the radial direction more obviously than in the axial direction,growing to the maximum along the radial direction and gradually reducing.It can provide a reference for selecting operating parameters for actual agricultural spray operations and the design of electrostatic nozzles through the research on breakup and droplet characteristics.
