基于剪切效应的气动雾化喷嘴试验研究

Experimental study on pneumatic atomizing nozzle based on shear effect

提出一种基于剪切效应的气动雾化喷嘴,对影响雾化质量的喷嘴结构参数进行试验研究.设计了3种气流孔径分别为8.0,9.0,10.0 mm的喷嘴,以自来水为工质,采用激光粒度分析仪和激光多普勒测速仪对不同喷嘴的雾化性能进行测量;描述气流孔径和气体流量对雾化微粒直径与速度分布的影响,量化并分析雾化微粒直径与速度之间的关系.结果表明:在同一气体流量条件下,采用气流孔径为10.0 mm的喷嘴所获得的雾化微粒速度最大、直径最小.随着气体流量增大,雾化微粒的速度增大,直径减小.随着距离喷嘴出口的轴向距离增大,雾化微粒直径先减小后增大,速度先增加后下降.对于气流孔径为10.0 mm的喷嘴,在距离喷嘴出口的轴向距离50.0 mm断面上,雾化微粒速度呈现双峰分布,在喷嘴轴心线附近出现谷值;在距喷嘴出口的轴向距离为200.0 mm的断面上,雾化微粒的速度在喷嘴轴线位置达到最大值.

A pneumatic atomizing nozzle operating based on the shear effect was proposed.The nozzle structural parameters which affected the atomization quality were experimentally investigated.Three kinds of air-injection nozzles with diameters of 8.0,9.0 and 10.0 mm were devised.Tap water served as the working medium,the laser particle size analyzer and a laser Doppler velocimeter were used to test the atomization performance.The effects of air-injection nozzle diameter and air flow rate on ato-mized particle diameter and velocity distribution of atomization droplets were described.Relationships between droplet diameter and velocity were quantified and analyzed.The results show that at the same air flow rate,the nozzle with the air-injection nozzle diameter of 10.0 mm is responsible for the highest droplet velocity and the smallest droplet diameter.With increasing air flow rate,the droplet velocity increases and droplet diameter decreases.As the axial distance from the nozzle outlet increases,droplet diameter decreases first and then increases,and droplet velocity increases first and then decreases.For an air-injection nozzle diameter of 10.0 mm,the droplet velocity exhibits a bimodal distribution at the axial distance of 50.0 mm from the nozzle outlet and the lowest velocity arises near the nozzle axis.At an axial distance of 200.0 mm from the nozzle outlet,the droplet velocity reaches maximum at the nozzle axis.