PIV技术测试聚合物流体拉伸流动的实验研究

摘要

针对低相对分子质量、低黏度的牛顿流体（如聚异丁烯）和非牛顿流体（如3％苯甲酸钠溶液），采用粒子成像速度仪（PIV）系统测试了2种流体在同一流率下流经渐变收缩流道时的速度分布，并研究比较了壁面处的纯剪切流动与流道中心轴线上的拉伸流动。通过实验测试与有限元模拟比较发现，牛顿流体和非牛顿流体的速度分布形态具有一定的差异。在速度分布确定的情况下，根据渐变收缩流动的特点，可以得到聚合物流体流动时中心轴线上的拉伸速率和边界处的剪切速率。%The velocity distribution and extensional flow behavior for Newtonian fluids （polyisobutylenes） with low molecular weight and low viscosity and Non-Newtonian fluids （sodium benzoate solution） while flowed through a continual contraction channel were determined and compared with the help of a particle image velocimetry system. The shear rate at wall of channel and extensional rate along its axis were estimated. The differences between the two fluids were analyzed and explained.