Widerstandsverminderung in turbulenten Rohrströmungen: Stabilitätsverhalten wäßriger Polyacrylamidlösungen bei mechanischer und thermischer Beanspruchung

Experimental results on the drag reduction efficiency of polymers based on acrylamide are represented and discussed. The measurements were carried out on a laboratory and a pilot plant scale. Points of main interest are the mechanical and thermal stability of the polymers. The laboratory tests, which were performed under well defined conditions, show the decisive influence of wall shear stress on degradation. These results explain the good stability, which has been measured in a technical pipeline. In the case of suspensions of coal in water a drag reduction efficiency interesting for technical applications has been observed, too. The thermal degradation of the polymer is accelerated by oxygen solved in the water. Under inert conditions only very small degradation effects occur even at temperatures up to 150 °C. GPC measurements give instructive results for an understanding of the thermal and mechanical degradation of the polymers on a molecular base.