練習帆船日本丸の帆の空力特性について

Abstract

The authors have carried out wind tunnel experiments on a 1/75 scale model of the sail training ship NIPPON MARU at Osaka University. The experiments consisted of two parts, one is flow visualization around wind speed vanes located on the top of jigger mast and the other is measurement of aerodynamic forces of the model. In visualization experiments, the wind has been getting over her sails. Particularly we have measured the angle of attack to the wind speed vane. As the propeller vane decrease measured wind velocity by the vertical angle of attack, we have corrected wind speeds and directions that had measured in 1986 on board experiments of the NIPPON MARU. Using those data we have identified aerodynamic coefficients, these are thrust force coefficient C_X, lateral force coefficient C_Y, yaw moment coefficient C_N and heeling moment coefficient C_K. We have compared them with wind tunnel tests results. And both results have coincided well in the thrust force coefficient C_X. But wind tunnel results are smaller than on board results in another three coefficients. It may be caused by the estimation of lateral water resistance that was fully depend on the leeway angle which was indicated with integer numbers by D.S. log.