5550TEU貨櫃船迴旋特性之數值研究

Numerical Investigation on the Turning Characteristics for a 5550TEU Container Ship

本研究應用野本謙作（Nomoto，1956）所提出的船舶操縱一階線性近似式，探討線性模式中之迴旋性指數（K值）、延遲性指數（T值）與船舶迴旋角速度間之關係。船舶操縱數值模擬採用日本MMG模式，對一艘船舶中心所設計之5550TEU的大型貨櫃船進行實船海試操船運動驗證，以確認數學模式之正確性。針對5550TEU船舶進行不同初始船速與不同舵角之系列定迴旋運動數值模擬，進而模擬出不同舵角下之迴旋運動反應，並藉由分析各時間點之迴旋角速度，計算出不同舵角下之K值與T值，建立大型貨櫃船在各種舵角之迴旋係數迴歸模式，並對大型貨櫃船之迴旋特性進行討論。最後將此簡化之迴歸模型所計算出來之迴旋角速度與數值模擬之結果進行比較，驗證此迴歸模型在操船避碰之實用性。 This paper presents the numerical study on the turning characteristics for a large container ship. The predictions of a practical tool for ship manoeuvrability have been used the MMG model, while the hydrodynamic coefficients are estimated with empirical formula and database from published papers. In order to clarify the validity of the proposed manoeuvrability prediction system, sea trial measured results of a 5550TEU container ship provided by SOIC have been compared with the simulation results by the present simulation system.Based on the numerical investigation of turning motion characteristics of the 5550TEU container ship with varied forward speeds and rudder angles, a simplified model proposed by the Nomoto (1956) has been used to investigate the turning characteristics of the 5550TEU container ship in this study. The effective time constant, T, and the rudder gain, K, can be obtained from the numerical simulations by using the regression technique with varied forward speeds and rudder angles. This simplified technique based on the database of manoeuvring parameters is very easy to find the helm angle for controlling the 5550TEU container ship to avoid collision at seas. Finally, a simple simulation case has been used to find the optimal helm angle of the ship and the comparison results have been discussed in this paper.