由波形分析改进长江客货船船型

本文基于线性兴波理论,采用波形分析法,对长江中、上游典型客货船“东38”型进行实船改型研究。在与该型同一主尺度系数的条件下,运用船型可分法的设计思想设计出928船型,并安装了首球鼻以降低其波形阻力。提出了根据实测波幅谱概估球鼻最佳尺度以及球鼻重心纵向位置移动对波形阻力影响的方法。 新设计的球首长尾轴套船型——928-Ⅲ型,球鼻前端完全不突出首垂线外,船后体的推进轴设计成用两个大型长轴套作支撑。在同一设计航速(Fr=0.282) 下,它比“东38”型降低总阻力17.5％,兴波阻力37％,波形阻力32％;提高推进效率20％,节省功率22～27％左右。     

Hydrodynamic optimization of a catamaran hull with large bow and stern bulbs installed on the center plane of the catamaran

Here, a numerical optimization procedure is proposed for a fundamental study of a fast catamaran, and we compare the wave-making characteristics of a catamaran hull form with and without large bow and stern airship-type bulbs installed on the center plane of a catamaran operating at high speed. The method involves coupled ideas from two distinct research fields: numerical ship hydrodynamics and a nonlinear programming technique. The wave-making characteristics of catamaran hulls with and without bulbs were investigated using the panel method applied to free surface flow (PAFS), in which Morinos method for lifting bodies is extended to analyze the problem of free surface flow, and PAFS is linked to the optimization procedure of the sequential quadratic programming (SQP) technique. An optimum hull form for a catamaran can be obtained through a series of iterative computations, subject to some design constraints. Here, only the hull shape of a catamaran is optimized with and without center-plane bow and stern bulbs. The optimization is carried out at two Froude numbers, 0.45 and 0.5, which are around the last hump of the wave-making resistance curve. The numerical results show that a reduction in wave-making resistance is achieved around the design speed.     

关于大型船舶试航测速的浅水修正方法

在分析了有关船舶在浅水水域试航速修正方法的基础上，推荐了Ａ．Ｍｉｌｌｗａｒｄ的三因次修正方法用于大型船舶在有限水深水域试航速的修正，文中给出的算例，表明在航速预报结果同相关方法相比，具有同一量级的精度，本方法可作为大型船舶试航航速修正或预报有一种估算方法。