Research on Propulsive Performance of Ships by Means of Computational Fluid Dynamics

在横滨国立大学海上流体力学实验室中，采用表面涡列法编制的计算机程序对螺旋桨的水动力特性进行了分析，但由于程序过于繁琐，耗费了大量的时间。本课题在本年度主要开展了两项研究工作，一是开发以面板法为备选方案的计算机程序代码，分析人的水动力特性。二是利用罗金源法编制了计算机程序，从理论上计算了双体船、三轴船等多体船舶的波浪和造浪阻力。面板法和朗肯源法在数学上都属于边界元法的范畴。它们不仅适用于非起重体，也适用于起重体。此外，由于它们的算法相对简单易懂，编程的工作量相对较少，计算时间也比表面涡旋字母法短。在这一年里，这些新的计算机部门取得了三个重要的成果。一是应用狄利克雷原理求解桨叶周围的速度场，如叶片正面和背面的交叉流。第二部分是三维机翼的计算机设计方法的发展，其截面能够实现先前给定的压力分布作为目标函数。最后，在国际上首次计算了三体船的生浪和造浪阻力。

The computer program cade by the surface vortex lettice method has been employed to analyze hydrodynamic characteistics of a propeller in the laboratory of maretime by hydrodynamics of Yokohama National University, However, the code is too heavy for a computer and consumes too much time. In this year two tasks has been carried out in this research project, One is the evelopment of the computer program code by the sarface panel method as the altenative cade to analyze the hydrodynamic characteristics of peopellers. The other is the development of the conputer program cade by Raukine source method to calculate theoretically the waves and wave making resistance of a multi-hulls ship, such as a catsmeran or a trimear. The surface panel method and Rankine sowce method both belong to the category of the boundary element method mathematically. They have advantage of availability to not only non-lifting bodies but also lifting bodies. Furthermore, since their algorisms are relatively simyple and easy to understand, the labow of programiing is fairly less and the computing time is also shorter than thesurface vortex lettics method. In this year three important results have been obtained by such new computer cades. One is the solution of the velocity field around a merine propeller by application of Dirichlet's principle, such as the cross flows on the face side and teh back side of the blade. The secondis the development of computer design mehod of a 3-dimensional wing, the section of which is able to realize the previously given prssure distributioin as the object function. The final is the computation generated waves and wave making resistance of a trimaran first all over the world.