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Hull form resistance performance optimization based on CFD
Published in Pentti Kujala, Liangliang Lu, Marine Design XIII, 2018
Baiwei Feng, Haichao Chang, Xide Cheng
The optimised ship resistance is calculated with the Shipflow tool during the optimization process. Computations are performed on a 2 CPU PC (Intel Core 3.10 GHZ, 4 GB RAM). The resistance curve trend of the two conditions is almost the same, as illustrated in Fig. 7. During the bulbous bow optimization stage, the total resistance decreases significantly at high speed (approximately 7%) and increases by approximately 3% before reaching the design speed (Fr = 0.27). This is because the bulbous bow increases the wet surface area, which results in higher friction resistance. At low speed, the wave-making resistance accounts for a smaller proportion; therefore, the total resistance increases. When the speed is increased above the design speed, the wave-making resistance component increases and the bulbous bow effect becomes obvious, which reduces the total resistance. Following optimization of the bow profile, it can be seen that, compared to the results of the first optimization step, the resistance performance is improved slightly when the speed is below the design speed. The optimization of the stern shape decreases the viscous pressure resistance and total resistance across the entire speed range, compared with the initial ship.
Experimental and numerical study on the scale effect of stern flap on ship resistance and flow field
Published in Ships and Offshore Structures, 2020
Ke-wei Song, Chun-yu Guo, Chao Wang, Cong Sun, Ping Li, Ruo-fan Zhong
For transom stern ships, when the ship speed exceeds a certain value, the stern flow detaches from the hull and the transom stern plate, forming a hollow behind the ship; subsequently, the water flow behind the ship converges to form a rooster tail, which is a typical flow field characteristics of the transom stern (Papanikolaou 2014). The speed at which transom clearance begins to occur corresponds to the critical Froude number. The ship resistance undergoes a sudden change at the critical Froude number, as reflected in Figure 10(a).