Practical evaluation of the drag of a ship for design and optimization

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• 作者：Chi YANG ; Fuxin HUANG ; Francis NOBLESSE
• 关键词：friction drag ; wave drag ; Neumann-Michell (NM) theory ; sinkage and trim ; nonlinear effects
• 刊名：Journal of Hydrodynamics, Ser. B
• 出版年：October, 2013
• 年：2013
• 卷：25
• 期：5
• 页码：645-654
• 全文大小：5051 K

文摘

We consider two major components of the drag of a ship, the 鈥渇riction drag鈥?and the 鈥渨ave drag鈥? that are related to viscous friction at the hull surface and wavemaking, and mostly depend on the Reynolds number and the Froude number, respectively. We also consider the influence of sinkage and trim, viscosity, and nonlinearities on the drag. The sum of the friction drag given by the classical ITTC friction formula and the wave drag predicted by the modification, called Neumann-Michell (NM) theory, of the classical Neumann-Kelvin theory of ship waves is found to be within about 10% of experimental drag measurements for four ship hulls for which theoretical predictions and experimental measurements are compared. The sum of the ITTC friction drag and the NM wave drag can then be expected to yield realistic practical estimates that can be useful for routine applications to design and hullform optimization of a broad range of displacement ships. Furthermore, we note several simple extensions of this highly simplified approach that can be expected to significantly improve accuracy.