フラップ舵を装備する船舶の操縦性能とその推定

概要

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Recently, the powerful high-lift type rudder such as a flapped rudder is widely used in order to improve a steering quality or to achieve the reduction of labour cost in ship operations. For the prediction of manoeuvrability with these ships, it has been done by means of employing some empirical amplification factor in the calculation of rudder normal force. This procedure, however, makes some problems. The empirical amplification factor differs depending upon rudder angle especially when the flap angle is not proportional to the rudder angle. It is not also proper when a ship is swaying and yawing, as the inflow angle to the rudder changes depending on the ship motion, but the flap angle is kept unchanged. These facts may cause the mis-prediction of the manoeuvrability. In this paper, a mathematical model is proposed to predict the manoeuvrability for a flapped rudder equipped ship. It has been validated by free-running model tests. Based on the proposed mathematical model, the suitable flap angle is investigated by the numerical simulations. Then, it is found that the smaller flap angle is better for the stable ship in course-keeping, and that the larger flap angle for the unstable ship, though the maximum flap angle is the same in each other.
社団法人日本船舶海洋工学会の論文