A COMBINED PIV LIF-SYSTEM FOR THE MEASUREMENT OF HETEROGENEOUS DRAG REDUCTION EFFECTS IN A PIPE-FLOW/

Particle Image Velocimetry (PTV) technique combined with flow visualiz ation was applied in heterogeneous drag reduction to examine the motio n of the polymer thread and the mixing process of polymer and water si multaneously at Reynolds numbers of 15000. The instantaneous velocity profiles for water/polymer motion showed in some cross-sections differ ences in the velocities of the two phases which indicates an interacti on between the polymer thread and the water phase. The results of this interaction have not a significant effect on the drag reduction compa red with the influence of the mixing process.