貨櫃船消浪式艉部船形實用設計之研究

A Practical Design Study of Wave-damping Aftbodies for a Container Ship

The primary focus of this research is to develop an effective wave-damping after body (WDA) for a container ship. Four different hull forms are analyzed, namely an original hull form, RD542-0, which was designed by CSBC Corp., Taiwan, and three further variations of this hull form, RD542-1, RD542-2 and RD542-3. The effects of the different hull-forms on wave resistance performance are evaluated by a CFD method which includes wave-making performance. The computational results for RD542-0 are firstly validated by comparison with experimental data from HSVA in Hamburg. The error is less than 5% for a grid with 1 million cells and smaller than 1% for a grid with 4 million cells. Additionally, longitudinal wave-cuts (shortly 'wave-cuts' in the rest of this paper) at a set of transverse locations show good agreement with data from a three-dimensional wave pattern measuring system at ESOE, NTU, Taiwan. Comparisons of the total resistance values, wave patterns, and wave-cuts in the stem region of all three hull forms show that RD542_2 has the best resistance performance, with a 1.76% reduction in total resistance compared to RD542_0, for model scale λ=23.76 and design speed 20.1 knots. This is due to the strong stem-wave damping effect produced by the aftbody shape, as demonstrated by the reduction of the stem-wave height and pressure-term of the ship resistance. 本研究主要之重點為針對一貨櫃船船形發展有效之消浪式艉部船形，其中針對四個不同船形加以分析，包括自台灣國際造船公司設計的原始船形RD542-0以及由此船形衍生的另外三個船形RD542-、RD542-2及RD542-3。這些不同船形在興波阻力性能呈現之效果利用計算流體動力學（CFD）方法加以評估，自RD542-0船形計算所得之結果先與在漢堡HSVA實驗之結果比較，以進行驗證。其中由網格數目為一百萬點之誤差值小於5%，而網格數目為四百萬點之誤差值則小於1%，此外，於不同橫向位置之縱向切面波形形狀顯示與在台灣大學工程科學及海洋工程學系水槽量得之波形有很好的一致性。經由總阻力、在艉部區域波形以及縱向切面波形形狀的比較，顯示RD542-2船形在RD542-0、RD542-1及RD542-2三個船形中有最佳的阻力性能，針對設計速度20.1節，在船模比例λ＝23.76之情況下其阻力比RD542-0船形減少了1.76%，若推算至實船，阻力降低值可達約5%，此乃得助於由新設計之艉部船形所產生之消浪效果，其中可由艉部波高的減低與船舶阻力壓力項的降低看出端倪。最後將RD542-02的艏部與RD542-2之艉部結合成衣混合船形RD542-3以整合二者個別的優點，根據HSVA的實驗結果，推估實船馬力降低值可進一步達到7%的效果。