孔板式节流元件后油滴剪切破碎的实验测试研究

围绕界面张力、黏度对孔板后液滴破碎程度的影响及孔板后切向、轴向、均方根速度场与粒径分布场之间的关系进行了实验研究。利用石英玻璃制造孔板节流管,采用高速摄像仪拍摄孔板前油滴并用软件分析确定其平均粒径,采用粒子动态分析仪(PDA)检测孔板后油滴平均粒径分布及各速度场分布。结果表明,分散相黏度和界面张力越大,液滴内部恢复力越大,油滴越不容易破碎;切向速度对液滴破碎程度影响最大。切向速度梯度变化是造成液滴破碎的主要原因,而轴向速度梯度和均方根速度梯度对孔板后液滴破碎影响不大,仅造成液滴的变形。孔板后适度旋流有利于液滴的聚结。

Experimental Tests on Oil Droplet Shear Fracture after Passing through Perforated-plate Throttling Element

The influence of the interfacial tension and viscosity on droplet breakage,and the relationship between size distribution and velocity field,such as tangential velocity,axial velocity,and root mean square velocity after orifice,were experimentally studied.In the experiment,the raw material of orifice throttling tube is quartz glass.The oil droplets before orifice was observed by High Speed Digital-Cram,and the average grain diameter was measured with software.The oil droplets size distribution and velocity field after orifice were measured by Particle Dynamic Analyzer(PDA).The experimental results show that the high dispersion phase viscosity and large interfacial tension lead to large droplet internal restoring force,so the degree of droplet breakage is to be rather low.Tangential velocity gradient is the main reason for droplet breakage.The gradient of axial velocity and root mean square velocity has little effect on droplet breakage,but it could induce the deformation of the droplet.The moderate rotational flow promotes the coalescence of droplet.