共查询到19条相似文献,搜索用时 140 毫秒
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《船舶力学》2016,(9)
计及多自由度运动的船舶斜航水动力预报对船舶航行安全具有重要意义。文章通过耦合求解船舶运动方程和雷诺平均N-S方程,并采用VOF方法和高精度自由面捕捉技术对作多自由度斜航运动船舶的粘性绕流场进行数值模拟。船舶动态平衡位置根据计算出的力和力矩来决定,得到包括升沉、纵倾和横倾在内的船舶浮态。文中采用的算例与爱荷华大学进行的模型试验相同,通过比较数值计算结果和试验值验证了该方法的有效性。对船模在受约束和自由运动两种状态下的船舶运动和流场进行模拟,通过比较分析船舶升沉、纵倾和横倾的影响。文中计算获得的详细流场细节特征,包括前体和舭部的涡以及船体表面上的压力,有助于理解船舶斜航运动浮态变化的机理。 相似文献
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浅水中的斜航船舶受到浅水阻塞效应和不对称流的综合影响。为预报该运动中的船舶水动力,文章采用基于定常雷诺平均纳维—斯托克斯方程的计算流体动力学方法,对浅水中做斜航运动的船舶粘性绕流场进行数值模拟。考虑低航速运动的特点,忽略航速影响下的自由面兴波,由数值计算得到水动力系数在漂角影响下的变化规律。针对计算精度问题,在数值模拟中从验证和确认角度分析和评估计算结果:通过网格收敛性分析分析数值误差与不确定度;结合试验数据考察计算模型的误差。此外,从计算区域尺度、湍流模型、边界条件、船体下沉和纵倾作用方面对模型误差的影响因素进行探讨,可为改进计算模型、提高数值模拟精度提供参考依据。 相似文献
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KVLCC2船模斜航运动粘性流场及水动力数值计算 总被引:1,自引:0,他引:1
采用CFD商业软件FLUENT对KVLCC2模型的斜航运动粘性流场进行数值模拟,计算得到了不同漂角时的横向水动力、首摇力矩、船体表面压力分布及尾流场,通过将计算结果与试验结果进行比较,验证了文中计算方法的有效性.文中采用SST k-ω和RNG k-ε两种湍流模式进行了水动力计算及流场数值模拟,通过将其结果与试验结果进行比较,得出了SST k-ω模式较RNG k-ε模式更为适合于实际船型的斜航运动粘性水动力计算和流场数值模拟的结论. 相似文献
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阐述采用符拉索夫拉沉性计算方法解决破损船舶总纵强度计算中的外载荷和破损模型等问题。研究破损船舶问题是在不沉性理论基础上进行的。首先从研究在静水中既朋纵倾又有横倾时船舶浮态参数入手,进而研究静置在波浪上的船舶浮态参数、波浪弯矩和波浪剪力。 相似文献
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潜艇做水平面转向运动时,指挥室围壳处于有漂角的斜流之中,受主艇体与围壳干扰后的流场作用于艇上产生的水动力与力矩,使潜艇常伴随出现另外2个坐标平面上的耦合运动,即横倾、纵倾和潜浮运动,而围壳的高度与外形特征对耦合运动的幅度有直接的影响.文中对一近似常规潜艇模型的指挥室围壳进行优化,得到了低矮化、流线型化的3种围壳模型,采用CFD方法计算比较了这几种模型在漂角β(0,°10°)内与耦合运动有关的水动力性能及表面压力分布,计算表明低矮化、后缘流线型化的围壳能有效降低艇体水平转向时的横倾与纵倾幅度,为潜艇指挥室围壳的外形优化设计提供参考. 相似文献
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本文综述了交通部上海船舶运输科研所及国外关于船舶变纵倾试验的结果,并通过作者对一些船舶的计算,阐明了船舶最佳纵倾航行法是一项切实可行的节能措施,一般可节油4~10%。文中给出了船舶试用最佳纵倾航行的实例;并指出了最佳纵倾节能是一个综合性的实用问题,必须从船处于纵倾状态时的稳性、强度、浮态、操纵性等方面加以权衡。例如在空载营运时应考虑浮态衡准要求;满载状态采用首倾航行应谨慎从事;半载或减载排水量状态能否采取首倾的最佳纵倾来营运?这应从挖潜致用、节能与安全观点出发,深入探讨。 相似文献
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浅水中船舶水动力特性数值计算 总被引:1,自引:0,他引:1
本文对浅水中船舶水动力特性进行数值计算研究.采用RANS方程结合RNG K-ε两方程湍流模型,对一方形系数0.6的系列60船模在浅水中的阻力、升沉、纵倾和兴波进行数值计算,其中自由面采用VOF方法处理;计算中,水深Froude数范围0.6~1.8,包含了临界和超临界水深Froude数.数值计算得到的阻力、升沉和纵倾与模型试验结果及采用三维扩展Boussinesq方程的计算结果进行了比较分析,吻合较好,部分计算结果得到改进. 相似文献
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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
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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
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Huaming Wang Xuhui Li Lin Chen Xiangjie Sun 《Journal of Marine Science and Technology》2016,21(4):601-610
In the present study, numerical simulation of the berthing maneuver of a ship in the prescribed translational motion is performed. The transient viscous flow and hydrodynamic forces on the hull are calculated by solving the unsteady Reynolds-Averaged Navier–Stokes equations in overset grid system, and the free surface is captured using volume-of-fluid (VOF) approach. The present numerical results have been compared with previous computational results by Toda and available experimental data respectively. Since the effects of the quaywall and free surface are taken into consideration in the present study, it is found that the agreement is significantly better than that resulting from Toda’s 3D CFD based approach. Then the effects of various standoff distances between the ship and quaywall on the lateral forces are investigated. Meanwhile, the detailed transient flow features around the berthing ship are obtained, which are helpful to understand the interactional effects between the ship and quaywall. The present results may provide helpful guidance for vessels’ safe maneuvering in berthing motion and the design of fender system in the quay. 相似文献
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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
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The wave-induced motions of ships in maneuvering condition are numerically studied based on potential theory. The total disturbance potential is decomposed into a basic part and a perturbation part. The basic flow is evaluated based on the double-body model with a trailing vortex sheet. The perturbation flow is solved by using a time domain Rankine panel method to determine the hydrodynamic forces, and the wave-induced ship motions are then evaluated by an Adam–Moulton scheme. The solving process of the wave-induced motion is integrated with the maneuvering prediction by using a two–time scale model. Numerical tests are firstly carried out for a Series 60 ship, and the numerical results are compared with the experimental data to validate the numerical method for the basic flow. Then the wave-induced motions of the S-175 container ship in straight course and in turning condition are simulated; the numerical results are compared with the ITTC data and the experimental data, which show fairly good agreements. 相似文献
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通过对潜体近水面航行波浪力作用下非线性运动响应进行建模和计算,揭示了由于二阶波浪力民低速时潜艇操纵面舵力之不足,潜体的定深控制可能难于实现,产生逐渐上浮与露出波面的非线性现象。计算结果与自由自航模的试验结果相当吻合。 相似文献