Abstract

In the present work, the particle image velocimetry (PIV) technique was used to measure the velocity components in the direction normal and tangent to the wall to obtain average velocity fields, wall shear stresses, friction velocity, drag reduction and average deformation fields were obtained by adding bubbles (injected by electrolysis), polymer (WSR-301 polyox) and surfactant (cationic) and their bubble-polymer, bubble-surfactant and polymer-surfactant combinations at concentrations of 164 and 272 ppm in a water flow in a channel (2cm x 10cm x 160cm) with a Reynolds number of 5200. Increased levels of drag reduction were obtained when combining the techniques, for example in the bubbles with polymers (WSR - 301 polyox) combinations, drag reduction results of 82 and 93 % were obtained for the concentrations of 164 and 272 ppm respectively, While when the combinations of bubbles with surfactants were used, the results were 37 % for 164 ppm and only 16 % for 272 ppm, and for the combination of polymer with surfactant for 164 ppm the results were 47 % and for 272 ppm the drag increased by 25 %, possibly due to an incorrect preparation of the polymer or surfactant, which leads to the conclusion that the greatest synergistic benefit is presented when combining the drag reducing techniques of bubbles and polymers.

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