| 摘要 |
PURPOSE:To improve the single efficiency of a propeller and its propulsive efficiency, by providing a front part guide fin, which generates a rotary flow of the same direction to the rotation of the propeller, in a boss part before the propeller and a rear part guide fin which generates a rotary flow in the opposite direction to the rotation of the propeller, behind the propeller. CONSTITUTION:Since a front part guide fin 5, which generates a flow component in the same direction to the rotation of a propeller, is provided before the propeller 4 in a boss part 3 of a stern part 2, power for rotating the propeller 4 can be decreased. Consequently, the propeller 4 small decreases the degree of its load large increasing the optimum pitch of the propeller, but its single efficiency improves. While the propeller 4 increases the rotary speed of its wake flow, but a rear part guide fin 9, which is radially provided with a rotary shaft of the propeller 4 serving as the center, converts energy of a rotary flow component behind the propeller 4 into thrust to be recovered.
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