共查询到20条相似文献,搜索用时 31 毫秒
1.
A flow-simulation method was developed to predict the performance of a sailing boat in unsteady motion on a free surface.
The method is based on the time-marching, finite-volume method and the moving grid technique, including consideration of the
free surface and the deformation of the under-water shape of the boat due to its arbitrary motion. The equation of motion
with six degrees of freedom is solved by the use of the fluid-dynamic forces and moments obtained from the flow simulation.
The sailing conditions of the boat are virtually realized by combining the simulations of water-flow and the motion of the
boat. The availability is demonstrated by calculations of the steady advancing, rolling, and maneuvering motions of International
America's Cup Class (IACC) sailing boats.
Received: December 25, 2001 / Accepted: March 26, 2002 相似文献
2.
A finite-volume method was applied to a simulation of the flow about the sail system of IACC sailing boats. The interface
boundary technique was employed to generate a proper grid system for the two-sails system, which is composed of head and main
sails. The turbulence model was carefully chosen by numerical test, and the most reliable simulation method was completed
and used to design the sails. The suitability of the method is demonstrated by some examples of design applications.
Received for publication on March 14, 2000; accepted on March 16, 2000 相似文献
3.
4.
Takuya Ohmori 《Journal of Marine Science and Technology》1998,3(2):82-93
A finite-volume method of computing the viscous flow field about a ship in maneuvering motion was developed. The time-dependent
Navier-Stokes equation discretized in the generalized boundary-fitted curvilinear coordinate system is solved numerically.
A third-order upwind differencing scheme, a marker and cell (MAC)-type explicit time marching solution algorithm and a simplified
subgrid scale (SGS) turbulence model are adopted. The simulation method is formulated, including the movement of a computational
grid fitted to the body boundary that allows computation of the flow field around a body under unsteady motion.
To estimate the maneuvering ability of a ship, the accurate prediction of the hydrodynamic forces and moments of the hull
is important. Therefore, experimental methods of finding the hydrodynamic forces of a ship in maneuvering motion, such as
the oblique towing test, the circular motion test (CMT) and planar motion mechanism (PMM) test, were established. Numerical
simulation methods for those captive model experiments were developed introducing computational fluid dynamics (CFD).
First, numerical methods for steady oblique tow and steady turn simulation were developed and then extended to unsteady forced
motion. Simulations were conducted about several realistic hulls, and the results were verified by comparisons with measured
results obtained in model experiments. Hydrodynamic forces and the moment, the longitudinal distribution of the hydrodynamic
lateral force, and the pressure distribution on the hull surface showed good agreement. 相似文献
5.
Evaluation of added resistance in regular incident waves by computational fluid dynamics motion simulation using an overlapping grid system 总被引:2,自引:0,他引:2
A computational fluid dynamics simulation method called WISDAM-X was developed to evaluate the added resistance of ships in waves. The Reynolds-averaged Navier–Stokes (RANS) equation was solved by the finite-volume method and a MAC-type solution algorithm. An overlapping grid system was employed to implement rigorous wave generation, the interactions of ships with incident waves, and the resultant ship motions. The motion of the ship is simultaneously solved by combining the solution of the motion of the ship with the solution of the flow about the ship. The free surface is captured by treatment by the density-function method. The accuracy of WISDAM-X is examined by a comparison with experimental data from a container carrier hull form, and shows a fairly good agreement with respect to ship motion and added resistance. Simulations were also conducted for a bow-form series of a medium-speed tanker to examine the effectiveness of the WISDAM-X method as a design tool for a hull form with a smaller resistance in waves. It was confirmed that the WISDAM-X method can evaluate the added resistance with sufficient relative accuracy and can be used as a design tool for ships. 相似文献
6.
CFD simulation of 3-dimensional motion of a ship in waves: application to an advancing ship in regular heading waves 总被引:1,自引:0,他引:1
A new computational fluid dynamics simulation method has been developed for the unsteady motion of a ship advancing in waves.
The objective is to evaluate the added resistance and predict the performance of a ship in waves. In this study, a finite
volume method, in the framework of a boundary-fitted grid system, is employed. The motion of the ship is solved with six degrees
of freedom by using the hydrodynamic forces and moments obtained from the solution of the simulation method. The marker–density–function
method is employed to calculate the nonlinear free surface. This method is applied to the coupled motion problem of heaving
and pitching.
Received for publication on Nov. 15, 1999; accepted on Nov. 18, 1999 相似文献
7.
This paper presents a study on the numerical simulation of planing crafts sailing in regular waves. This allows an accurate estimate of the seas keeping performance of the high speed craft. The simulation set in six-degree of freedom motions is based on the Reynolds averaged Navier Stokes equations volume of fluid (RANSE VOF) solver. The trimming mesh technique and integral dynamic mesh method are used to guarantee the good accuracy of the hydrodynamic force and high efficiency of the numerical simulation. Incident head waves, oblique waves and beam waves are generated in the simulation with three different velocities (Fn =1.0, 1.5, 2.0). The motions and sea keeping performance of the planing craft with waves coming from different directions are indicated in the flow solver. The ship designer placed an emphasis on the effects of waves on sailing amplitude and pressure distribution of planing craft in the configuration of building high speed crafts. 相似文献
8.
基于模糊综合评价的帆船行驶最优路径规划方法 总被引:6,自引:0,他引:6
路径规划是帆船比赛取胜的重要环节。综合栅格法和模糊概念,提出了基于模糊综合评价的帆船行驶最优路径规划方法。该方法采用栅格法建立帆船航行的二维平面信息,以模糊逻辑为基础,结合帆船的运动信息建立帆船在运动平面上的二维隶属函数模型,并采用模糊综合评价思想,综合考虑行驶速度和接近目标2个因素建立综合评价函数,进行行驶方向决策。利用宽度优先搜索算法实现全局最优路径搜索。仿真结果证明,该路径规划方法能够取得较好的规划结果,对指导帆船运动员进行科学训练有很好的应用价值。 相似文献
9.
考虑到半潜船海上运输超宽悬垂货物过程中可能发生波浪砰击,提出利用波浪势流理论及超宽悬垂货物海运过程中砰击控制条件的数值模拟方法,以半潜式“海上渔场”载运为例,利用OCTOPUS软件建立计算模型,模拟海运过程中不同海况、航行吃水及航速情况下,船舶横摇、纵摇、垂荡、“海上渔场”砰击发生概率及砰击载荷的变化情况,“海上渔场”海运过程砰击数值模拟结果与工程实际数据十分吻合,验证了数值模拟方法的合理、可行。 相似文献
10.
11.
船艇水动力的计算方法目前主要有模型实验法、理论经验估算法和计算机模拟法.为了更好地预报船艇水动力性能,运用不同方法对2种典型船艇在不同漂角下运动时横向力进行计算,并对各自结果进行了对比分析,得出各种计算方法的优缺点.研究表明,流体计算软件(Fluent)精度较高,计算速度快,能解决人脑有时不能解决的问题.同时,Fluent计算软件为船艇水动力性能的预报等研究提供良好的方法和有益的探讨. 相似文献
12.
基于不同航行状态无人艇的水动力模型研究 总被引:1,自引:1,他引:0
无人艇操纵灵活,机动性强,在很多方面都有着广泛的应用。但相关研究还比较少。以往的单一水动力模型只是针对特定航行状态进行研究,对于不同的航速,单一的水动力模型已不再适用。因此随着航速不同,建立同一艘无人艇在不同航行状态下的水动力模型,并研究在此模型下无人艇的运动特性成为一个难点,也是研究真实无人艇的一个关键环节。论文在以往学者的研究成果基础上,给出了一种全新的水动力模型,并就某一真实无人艇,研究从静止到高速起滑整个过程的水动力与航速之间的开环变化关系。仿真结果表明了所给模型的有效性。 相似文献
13.
Nowadays, several stern devices are attracting a great deal of attention. The control surface is an effective apparatus for improving the hydrodynamic performance of planing hulls and is considered an important element in the design of planing hulls. Control surfaces produce forces and a pitching moment due to the pressure distribution that they cause, which can be used to change the running state of high-speed marine boats. This work elaborates a new study to evaluate the hydrodynamic performance of a planing boat with a trim tab and an interceptor, and optimizes them by using an optimization algorithm. The trim tab and the interceptor have been used to optimize the running trim and motion control of semi-planing and planing boats at various speeds and sea conditions for many years. In this paper, the usage of trim tab is mathematically verified and experimental equations are utilized to optimize the performance of a planing boat at a specificd trim angle by using an optimization algorithm. The genetic algorithm(GA) is one of the most useful optimizing methods and is used in this study. The planing boat equations were programmed according to Savitsky's equations and then analyzed in the framework of the GA-based optimization for performance improvement of theplaning hull. The optimal design of trim tab and interceptor for planing boat can be considered a multiobjective problem. The input data of GA include different parameters, such as speed, longitudinal center of gravity, and deadrise angle. We can extract the best range of forecasting the planing boat longitudinal center of gravity, the angle of the trim, and the least drag force at the best trim angle of the boat. 相似文献
14.
15.
水下拖曳系统水动力特性的计算流体力学分析 总被引:1,自引:0,他引:1
提出了一种新型的水下拖曳系统三维水动力数学模型。在该模型中拖曳缆绳的控制方程由Ablow andSchechter模型给出,Gertler and Hargen的水下运载体六自由度运动方程被用来描述拖曳体的水动力状态。通过对拖曳缆绳和拖曳体的控制方程在连接点处进行边界条件耦合,从而构成整个拖曳系统的水动力数学模型。在研究中,拖曳系统的水动力数学模型通过时间与空间的中心差分方程来逼近,每一时刻拖曳体所受的水动力通过求解Navier-Stokes方程得到。所提出的模型特别适用于拖曳体为非回转体、非流线型的主体,或必须考虑拖曳体各组成部分的水动力相互影响的情况。计算结果与相应的实验室样机试验结果的比较表明,所提出的模型可以有效地预报拖曳系统的水动力特性。利用所提出的水动力模型,对华南理工大学提出的自主稳定可控制水下拖曳体在实际海况下的数值模拟结果显示,所分析的拖曳体具有良好的运动与姿态稳定性,是一种值得开发研究的新型水下拖曳体。 相似文献
16.
17.
18.
19.