Abstract
The effect of a boundary-layer injection of drag-reducing additive solutions on the lift and drag of a 10-cm chord, NACA 63A020 symmetrical two-dimensional hydrofoil was investigated for various freestream and injection velocities, foil incidences, and additive concentrations ranging from 50 to 400 ppm of POLYOX WSR 301. The experimental results demonstrate that the lift of the hydrofoil can either increase or decrease depending upon whether the polymer injection is made on the suction or pressure side of the foil surface, respectively. In both cases, however, the drag is reduced. The net result of the injection of the drag-reducing agent is an augmentation of the lift-drag ratio. The magnitude of this augmentation and its dependence on the freestream velocity, the injection velocity, the concentration of polymer, and the incidence of the foil are analyzed.
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