- 學位論文
貨櫃船自推試驗之計算模擬
Numerical Simulation of the Self-Propulsion Model Tests for a Containership
摘要
本研究目的為藉由計算流體力學方法模擬單獨螺槳試驗以及貨櫃船自推試驗進而推估實船下之轉速與馬力。研究方法為使用雷諾平均那維爾史托克方程式求解器並搭配適當的紊流模型。螺槳轉動方法於單獨螺槳模擬採用旋轉參考座標系方法，自推試驗模擬則是採用旋轉網格方法。 在單獨螺槳模擬結果發現其效率最高點位於J為0.85處，此部分模擬結果與實驗結果吻合。藉由螺槳入流攻角及數值敏感度來探討其誤差來源，發現於J值較小時其螺槳入流攻角容易接近失速攻角，反之J值較大時容易受到數值敏感度影響造成誤差，但其效率誤差都在4%內。最後透過分析其翼斷面雷諾數，探討在近軸處和低轉速下的誤差來源，提出適用於模型尺度下的入流與轉速搭配建議。 自推試驗模擬需花費大量計算時間與資源，本文研究提出簡化自推試驗模擬之方法並針對跡流場速度進行探討，發現其總跡流速度大於有效跡流速度，且有效跡流速度大於名義跡流速度，此結論符合跡流場物理現象，將數值模擬結果與同排水型船之自推實驗進行比對，發現大致參數在定性上為合理的，此外在模擬中發現當螺槳模型過小，可能存在尺度效應問題，因此也藉由分析不同尺度下之雷諾數，給出適當之模型縮尺比。
並列摘要
We present some studyings for propeller open- water test and self-propulsion model test by using CFD simulation, estimate rotating speed and engine power of the full-scale ship from those simulation results. The flow field was solved by using Reynolds-averaged Navier-Stokes equations (RANS) solver with a proper turbulent model. Moving-Reference-Frame-System and Moving-Mesh-System were used to simulate the rotated propeller for open-water test and self-propulsion model test respectively. The results of the propeller open-water test simulation show that there has a most efficient operation point when J is equal 0.85; it is verified with experimental data. We also discuss the error by using analyze the propeller angle of attack and numerical sensitivity, it shows that angle of attack was closed to angle of stalling when J is lower , and the error was increased from the effect of numerical sensitivity when J is larger, but both errors of effective were below 4%. A discussion for the error of the propeller of the part near hub in low rotating speed by using analyzes the Reynolds number on the difference blade cross-section, and addresses an advice of the collocation between flow velocity and rotating speed. Computational Simulation of Self-Propulsion cost a lot of time and resources. We offer the method of simplified self-propulsion of Simulation. For wake velocity, the total wake velocity is higher than effective velocity, and the effective velocity is higher than nominal velocity. The comparison of a similar hull and propeller efficiencies was close to experiment. In addition to, the errors were attributed to the insufficient local Reynolds number at the propeller. Finally, we show an advice for choose the model scale by using analyze Reynolds number on the difference blade cross section.