正方形小通道内的非牛顿流体-氮气两相流动流型的实验研究

对水力直径为2.5 mm的正方形小通道内的非牛顿流体-氮气的垂直向上两相流动流型进行了可视化实验,工质分别为:浓度0.2%的聚丙烯酰胺(PAM)和0.2%的黄原胶(XG)水溶液,表观气速0.1～100 m/s,表观液速0.01～6 m/s.观察到的典型流型有:弹状流、搅拌流、弹环状流和环状流,其中弹环状流未见于水-空气上升流动.在PAM-氮气实验中发现了一种新流型-泡状-弹状流.通过流型图对比,发现非牛顿流体的搅拌流区域较牛顿流体窄,弹状-搅拌流转变线也明显右移,非牛顿流体的黏性对流型转变的影响较大.

NITROGEN/NON-NEWTONIAN FLUID TWO-PHASE FLOW IN SQUARE MINICHANNELS

Experiments of visualized nitrogen/non-Newtonian fluid two-phase upward flow are conducted in a square minichannel with a hydraulic diameter of 2.5 mm.TWO non-Newtonian aqueous solutions are used as the working fluids,namely,0.2% polyacrylamide(PAM)solution,and 0.2% xanthan gum(XG)solution.The gas superficial velocity ranges from 0.1 to 100 m/s and liquid superficial velocity from 0.01 to 6 m/s.Some representative flow patterns are observed as slug flow,churn flow,slug-annular flow,and annular flow,while the slug-annular flow is not found in nitrogen-water two-phase flow.A new flow pattern,named bubbly-slug flow,is found in nitrogen-PAM two-phase flow.The comparisons of flow regime maps show that the churn flow region of gas/non-Newtonian two-phase flow is narrower than that of gas/water flow;and the slug-churn transition limit of gas/non-Newtonian flow moves rightward apparently.It indicates that viscosity of the non-Newtonian solution influences the flow pattern and its transition remarkably.