ある横帆模型の空力特性と帆まわりの流れについて

抄録

Through wind tunnel experiments, aerodynamic characteristics are presented for a square sail model of sail training ship, NIPPON MARU. Unlike of large aspect ratio wings which show a phenomenon of stall, the lift coefficient of the sail increases its value with increasing attack angles and the maximum value reaches 1.3 or more at 45〜48 degrees of the attack angle. Even for more larger angles, there are no stall and the lift coefficients gradually decrease the value. The flow visualization was conducted in order to provide the information for the lift-drag phenomena utilizing smoke wire technique. The results tell us that a pair of free vortecies generated from upper and lower ends of the sail looks comparatively large for the sizes of the sail and then the down wash due to the vortices also becomes large as to delay the growth of separation. In test results of the fore mast model with 6 square sails, the lift coefficient curve shows the same tendencies with the one for the single square sail. But the maximum lift coefficient is 1.03 at 30 degrees of attack angle.