斜航狀況下潛艦周圍流場之計算

Abstract

本研究以一艘模仿德國S209-1400型潛艦外型為對象，利用CFD方法進行斜航狀態時的流場計算，計算方法採用有限體積法，以結構化網格，計算穩態的黏性流場。在計算潛艦周圍流場之前，先對KVLCC2這艘油輪進行斜航時的穩態流場計算，因該油輪已有實驗資料，藉由與實驗資料比對，以便先針對斜航計算所採用之方法進行驗證。油輪的計算條件為弗勞得數(Froud number) 0.142以及雷諾數(Reynold number) 3.945x106，斜航的角度為平擺(yawing)0、3、6、9與12度。計算結果和實驗結果比較，在阻力方面誤差約在10%以內，在流場局部數值(船殼表面壓力分布、流場速度分布)方面則和實驗相當接近。 接著進行潛艦斜航狀況下的流場計算，潛艦的計算條件為雷諾數9.86x107。其中裸船殼的部分：縱搖方向斜航，計算-20~20等18個斜航角度；平擺方向斜航，計算0、1、2、3、4、5、6、7、10、15、20等11個斜航角度；潛艦(含帆罩、控制翼)部分：縱搖方向斜航，計算-15~20等8個斜航角度。計算結果顯示，潛艦的附屬物在潛艦斜航時，對於船體周圍流場以及船體阻力皆會產生重大影響。另外將計算結果與實驗結果相比較，在力與力矩係數與斜航角度關係方面不僅趨勢上吻合，數值上的誤差都在可接受的範圍。

The turbulent flow field around the KVLCC2 tanker and the submarine are numerically simulated by solving the Reynolds Averaged Navier Stokes equations. Finite volume method is implemented in the RANS solver and the structured grids are used. For the KVLCC2 tanker in steady drift motion without the free surface, computations are carried out at angles of yaw from 0 to 12 degrees in model scale. The computational results are validated against the experimental data provided by the “CFD Workshop Tokyo 2005” in terms of various global and local quantities. All the results are in good agreement with experimental data. For the submarine in steady drift motion, the hull form of submarine is imitation of German S209-1400 submarine. Computations for bare hull are carried out at angles of pitch from -20 to 20 degrees and angles of yaw from 0 through 20 degrees. Additionally, simulations for the submarine with appendages including sail and control fins are performed at angle of pitch from -15 to 20 degrees. The simulated results show that the appendages (sail, control fins) have great influence on flow field and resistance of the submarine. The simulated results also compare with experimental data. The comparison result shows that the present computational approach predicts the outstanding force coefficients and moment coefficients well.