迎角およびヒ-ルアングルの変化による円型オッタ-ボ-ドの性能と安定性

概要

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The efficiency and stability of simplified plastic saucer-shaped otter board models with seven kinds of camber (0, 5, 7.5, 10, 15, 20, 25%) were studied. Models were rigged for an attack angle of between 0° and 50° and for an inward heel angle of between 0° and 20° at 5-degree intervals. The horizontal lift, drag and moment were measured by a three component load cell in a circulation-type test tank. Lift and drag coefficients, lift-drag ratio and coefficient of pressure centre were then calculated.The lift and drag coefficients became smaller when the angle of heel was gradually increased from 0° to 20°. The coefficient of pressure centre increased with increase of the camber. Considering the mean lift-drag ratio which was calculated using the width of 5° on both sides of the attack angle at the maximum lift-drag ratio for all models, the optimum camber of the otter board was from 5 to 7% while the most effective heel angle was 5° inwards. However, otter boards with higher camber of 13-23% seemed to be more stable judging from both the width of attack angle at 75% of the maximum lift-drag ratio and the mean coefficient of pressure centre within 5° on each side of the attack angle at the maximum lift-drag ratio.
日本水産學會の論文