| 中文摘要 |
大型船舶的推進效率提升常著眼於螺槳跡流場中的旋向動能回收，實作上可分類為在螺槳前方預先將流體反向旋轉和在螺槳後方安裝附屬物轉換旋向動能為推力，不對稱船艉即屬於前者；本文首先建構參數化船艉扭轉變形方法，其中使用4個參數：旋轉強度、縱向分佈函數權重控制因子、剖面曲線旋轉角度分佈帶寬及剖面曲線旋轉極值位置，將任意左右對稱之船型曲面變形成不對稱船艉。本文選用由KRISO研究所公開發表之貨櫃輪KCS和附屬的五葉螺槳為研究對象，以商用計算流體力學軟體Star-CCM+進行流場模擬，並和實驗結果進行比對，以驗證計算結果的可信度。接著改變幾何變形參數建立各式不對稱船艉船型，於設計船速24節下進行阻力試驗模擬，並提出旋流係數進行分析。最後選擇效果最佳之船型進行自推試驗模擬，分析推進效率及船艉流場，進一步討論不對稱船艉於推進效率之效果。與原對稱船型相比，DHP下降0.8%，螺槳效率提升0.67%，顯示不對稱船艉之效果。
The propulsive efficiency of containerships usually is related to the tangential momentum loss in the wake zone behind the propeller. An asymmetric stern is an example to elevate the efficiency practically by pre-rotating the flow field in front of the propeller. In the presented study, a parametric transformation model applied to stern lines was constructed. The transformation includes three parameters: twisting strength, longitudinal distribution and radial distribution, to transform an arbitrary symmetric hull form into an asymmetric one while keeping the surface smoothness. The tested model in this study was the containership published by KRISO along with its propeller. The CFD tool STAR-CCM+ was used to simulate the resistance and propulsion tests, and then compare the result with the experimental data for validation. In addition to the nominal wake fraction, which solely accounts for the axial velocity, the tangential velocity distribution was evaluated. To discuss the relation between the transformation parameters and the axial/tangential velocity distribution in the wake zone, we studied 25 versions of asymmetric sterns and found the best parameter combination that achieved the optimal tangential velocity distribution. For the propulsion simulations, the delivered horse power can be reduced by 0.8% at the same propeller load. |
本站僅提供期刊文獻檢索。
