» Research » Drag Reduction and Rheology of Industry-important Materials

Drag Reduction and Rheology of Industry-important Materials

Main research domains

  • theoretical and experimental investigation of drag reducing micellar systems
  • rheology of surfactant solutions
  • turbulent structure of the surfactant flow in pipes and beyond simple singularities
  • theoretical and experimental investigation of the complex rheological characteristics of industry-important non-Newtonian fluids

Most important results

  • It was found that mechanical shearing has a substantial influence on micellar structure of drag reducing surfactants.
  • Prime responsibility for drag reduction phenomenon is in viscous behaviour and formation of Shear Induced Structure rather than in elasticity of the solution. The insight in micellar structure revealed some aspects of drag reducing phenomenon.
  • An approximate maximum drag reduction asymptote in surfactants was established which shows that effectiveness in drag reduction by means of surfactants is higher than in polymer solutions.
  • The turbulence structure in surfactants differs profoundly from the one in water.
  • The dependence of mean velocity profile on the Reynolds number and its large slope marks the dissimilarity of surfactants to polymer solutions.
  • Measurement of micellar size by light scatter and by electron microscope showed coincidence in order and confirmed the rod-like shape.
  • Usage of micellar additive in district heating system proved the possibility of saving one third of power consumption.
  • Concentrated oil/water emulsions from the rheological point of view are thixotropic plastic semisolids that change their plastic character with changes in the portions of the fat and aqueous phases (with increasing water content the curvature of the flow curve is lower).
  • A new precise and objective rheometrical method enables the determination of the rheological properties and stability of concentrated emulsions over wide temperature and shear rate ranges.
  • Concentrated (typically 6%) solutions of a polystyrene-polyisoprene diblock copolymer in low viscosity parafinic solvents form a micelle system by precipitating the polystyrene blocks, whereas the polyisoprene blocks are in solution. Besides viscoplastic behaviour without thixotropy, this system exhibits a pronounced shear thickening in steady-state flow. These copolymer solutions may be used as a standard material for viscoplastic bodies.
  • Using viscometry and dynamic and steady shear measurements it was found, that the thickening effect of the lattices dispersions (ethyl-acrylate-methacrylic acid copolymer) is explained by the formation of an ordered structure and strongly depends on their particle structure and the intensity of interactions between the components in system. The flocculation behaviour is explained by changes of the electrical charge and the free volume.