Study on the Performance of Two-dimensional Hydrofoils in Dilute Polymer Solutions

Abstract

The pressure distributions of hydrofoils in dilute polymer solutions were measured. The cross sectional shapes of hydrofoils were NACA-0006 and NACA-2412 profiles. The differences between the characteristics of hydrofoils in dilute polymer solutions and those in pure water were classified. Furthermore, the mechanism of the change in characteristic was investigated by measuring the velocity distribution in the boundary layer with a Laser Doppler Velocimeter. The results show that the performances of the foils depend on the development of a boundary layer. The lift coefficient of NACA-0006 section increases and its drag coefficient decreases because of a decrease in scale of a separation bubble on the suction side. The lift coefficient of NACA-2412 section decreases at small incidence angles because of an increase in thickness of the boundary layer, and increases at larger incidence angles due to a downward movement of the separation point.