水溶性高分子の被覆による乱流抵抗の低減

抄録

The turbulent drag reduction by means of polymer coating was investigated in a rectangular channel flow. The wall surface was coated with a water-soluble polymer that exhibited turbulent drag reduction as a solution. Two coating method were applied to the channel wall. In the first method, a binding polymer solution was mixed with an additive solution, and the mixed solution was applied and dried on the wall. The additive molecules were anchored on the wall by the binding polymer. This coating method produced the drag reduction of 7% at Re-4000. The drag reduction disappeared in high Reynolds number, and its mechanism was supposed to be different from normal Toms effect. In the second method, the additive power was stuck with paste on an adhesive vinyl tape, which was fixed on the wall surface. The drag reduction obtained was dependent on time. The reducing rate was 4.5% after 10 minutes, and 0% after 60 minutes. In this method, the solved polymer played an important role in the drag reduction. These coating methods are expected to open new additive application for outer flow.