The relation between the drag reduction (DR) performance of several water-soluble polymers and their viscoelastic properties was investigated. Polymers with a flexible molecular structure including three grades of polyacrylamides (PAM), and a polyethylene oxide (PEO) were investigated. Xanthan gum (XG) and carboxymethyl cellulose (CMC), each with a rigid molecular structure, were also considered. The rheology was characterized using steady shear-viscosity measurement, capillary break-up extensional rheometer (CaBER), and small-amplitude oscillatory shear measurement at the concentration of the drag-reduced solution. To isolate the effect of shear viscosity, the concentration of the polymers was adjusted to produce solutions with a similar shear viscosity at high shear rates. Using pressure drop measurements in a turbulent pipe flow, the DR of each polymer solution was determined. With identical high-shear-rate viscosities, the flexible PAM solutions resulted in an initial DR of 50–58%, while the initial DR of PEO was 44%, and the rigid polymers provided the least DR of 12%. The rigid polymers demonstrated negligible degradation of DR over a period of 2 h. Of the flexible polymers, PAM showed moderate degradation, while the DR of PEO quickly diminished after 20 min. Drag reduction correlated with extensional viscosity and Weissenberg number obtained from CaBER. A strong correlation was not observed between DR and the viscoelastic moduli obtained from small-amplitude oscillatory shear. The large mechanical degradation of PEO was associated with a continuous extensional thickening, in which extensional viscosity increased with decreasing strain rate until the filament broke up.

研究了几种水溶性聚合物的减阻性能与其粘弹性之间的关系。研究了具有柔性分子结构的聚合物，包括三种等级的聚丙烯酰胺（PAM）和聚环氧乙烷（PEO）。还考虑了各自具有刚性分子结构的黄原胶（XG）和羧甲基纤维素（CMC）。使用稳定的剪切粘度测量，毛细管破裂伸长流变仪（CaBER）和在减阻溶液浓度下的小振幅振荡剪切测量来表征流变学。为了隔离剪切粘度的影响，调节聚合物的浓度以在高剪切速率下产生具有相似剪切粘度的溶液。在湍流管道中使用压降测量，测定每种聚合物溶液的DR。在相同的高剪切速率粘度下，柔性PAM解决方案的初始DR为50-58％，而PEO的初始DR为44％，而刚性聚合物的DR最小，为12％。刚性聚合物在2小时内显示出可忽略不计的DR降解。在柔性聚合物中，PAM表现出中度降解，而PEO的DR在20分钟后迅速降低。减阻作用与从CaBER获得的拉伸粘度和Weissenberg数相关。在DR和从小振幅振荡剪切获得的粘弹性模量之间未观察到强相关性。PEO的大机械降解与连续拉伸增稠有关，其中拉伸粘度随着应变率的降低而增加，直到长丝断裂。