Abstract: The dispersion and movement features of the hollow cone spray droplets in confined crossflow in a square duct were measured with PIV technology on a self-established cold mixing rig.The droplet dynamics and vortices structures induced in the confined mixing flow field were obtained.The droplet dispersion in the mixing process was mainly influenced by several large-scale vortex structures，such as the counter-rotating vortex pairs (CVPs).The CVPs had a greater centrifugal effect on droplet dispersion because of preferential concentration so the droplets tended to accumulate along the edges of vortex structures.The main parameters affecting the mixing，such as crossflow velocity，atomization pressure and size of spray droplets were discussed and the curves of relationship between them and the best mixing effect were established.The mixing for double nozzles was also investigated and the influences of different injection angles on the mixing were discussed.The results showed that the way to improve the mixing was to avoid the stable large-scale vortex structures which could lead to non-uniform droplet dispersion and concentrations in the mixing flow field by controlling local droplets’ contribution and dispersion by convection.Mixing could be enhanced by turning the spray direction against the crossflow，increasing the nozzle number and choosing the appropriate crossflow velocity.The analytical approach and research findings have important practical significance for the mixing chamber design and performance improvement for relevant industrial applications.

Key words: mixing, droplet dispersion, vortex structures, PIV

摘要： 在自建的冷态横流-旋流喷雾两相掺混系统实验台上，采用PIV测量了掺混通道内气液两相掺混过程中液滴群的运动特性，获得了掺混流场中不同位置的液滴分布图像与流场结构特性。实验段结构为方腔（横截面尺寸为95 mm×95 mm），喷嘴采用空心锥形雾化喷嘴。对影响掺混效果的主要参数（横流速度、喷嘴雾化压力、喷嘴雾化粒径）进行了详细研究，绘出了最佳掺混效果下各参数关系曲线。掺混过程主要受不同尺度的旋涡结构影响，液滴多富集于旋涡边缘，稳定的大尺度涡不利于掺混。提高掺混效果的途径即是避免流场中出现稳定的大尺度旋涡结构，采用喷嘴前倾布置、增加喷嘴个数、确定合适的横流速度均是提高掺混效果的有效途径。分析方法与研究结果为工程实际应用中掺混室结构的设计及掺混性能的改进提供了依据和参考。

关键词: 掺混, 液滴分布, 旋涡结构, PIV