三体船粘压阻力预报方法

Estimation Method of the Viscous Resistance for Trimarans

三体船快速性的研究是三体船新船型开发技术的支撑。通过模型试验与数值模拟相结合的方法,对不同航速下三体船的粘压阻力进行计算。试验研究采用将三体船侧体分别放置在船中、船前部和船后部3个不同的纵向位置以及距船中心线3个距离不同的横向位置,测量9个侧体位置下三体船在静水中的总阻力。运用第八届ITTC公式计算摩擦阻力系数,进而算出剩余阻力系数。通过数值模拟的方法,基于细长体理论对三体船兴波阻力系数进行计算,再根据三因次换算方法计算粘压阻力系数。得出不同构型下三体船在静水中的粘压阻力系数,并作出其随Fr数变化的曲线,观察在侧体位置不同的情况下,三体船的粘压阻力系数随航速变化的规律。根据所得粘压阻力系数曲线,提出初步预报三体船粘压阻力系数的一种简单方法。

The research on the rapidity of trimarans is a major technical support for the development of new trimaran hulls. In this paper, the viscous resistance of trimarans with different speeds under the calm water condition is calculated through both experiments and numerical simulations. Particularly, the experiment is based on the measurement of the outriggers＇ resistance at three different longitudinal positions, namely the foreship, amidship, and rear, and three horizontal positions with different distances from the centerline. Next, the ITTC-57 formula is adopted to calculate the frictional resistance coefficient and residual resistance coefficient, so that the wave-making resistance of trimarans may be obtained according to the slender body theory. Finally, the viscous resistance coefficient is estimated via a three dimensional conversion, based on which the diagram demonstrating how it varies with Froude number is drawn. Also, this diagram reveals the relationship between the viscous resistance coefficient and the trimaran speed. Overall, the presented diagram provides a more intuitive way to roughly estimate the viscous resistance coefficient of trimarans.