DIFFERENCES IN THE FLOW BEHAVIORS OF POLYMERIC AND CATIONIC SURFACTANT DRAG-REDUCING ADDITIVES

Research on cationic surfactant drag-reducing additives has grown in r ecent years because of their repairability after shear degradation, ma king them suitable for potential applications in recirculation flows s uch as district heating and district cooling systems. Substantial diff erences between their flow behaviors and those of high-polymer, drag-r educing additives have been found. These include the influence of pres hearing, the effect of mechanical shear on degradation, the influence of tube diameter, maximum drag-reduction effectiveness, and the shape of their mean velocity profiles. Examples of these different flow beha viors are described. The differences suggest that the mechanisms for c ausing drag reduction may be different for the two types of additives.