共查询到20条相似文献,搜索用时 187 毫秒
1.
通过建立水下航行体空间的操纵运动数学模型,运用Visual C++设计开发水下航行体操纵运动预报系统,对水下航行体水平面、垂直面及空间典型操纵运动进行数值预报,数值模拟结果合理,能够较为全面地预报水下航行体的空间操纵运动。 相似文献
2.
中国南海区域海洋内波出现频率较多。海洋内波携带着巨大能量,对于水下航行体的安全航行具有非常大的威胁。为了研究内波对水下航行体的水动力性能影响,该文基于RANS方法和KdV理论建立了分层流中的内孤立波与水下航行体相互作用的数值模拟方法。在对约束模型数值模拟分析的基础上,采用DFBI方法结合重叠网格技术,开展了内孤立波作用下水下航行体自由运动的数值模拟。分析表明,内孤立波与航行体相遇,会使得其周围流场变得异常复杂,从而引起突变的流体动力和运动,对此时的航行安全性应给予极大重视。 相似文献
3.
4.
5.
6.
潜艇PMM实验的CFD仿真技术研究 总被引:1,自引:0,他引:1
操纵性是现代潜艇最重要的总体性能之一.为预报潜艇的操纵性能,需求得所有的水动力导数.借助CFD技术和动网格技术数值模拟小振幅平面运动机构试验,求解了SUBOFF主艇体的水动力导数,并与混合分布法计算的附加质量项作了比较,二者符合良好,从而验证了方法的有效性.流场的求解基于RANS方程和RNG k-ε湍流模型,动网格的处理采用Hrvoje Jasak和Zeljko Tukovic的方法,压力和速度的耦合采用PIMPLE方法解耦.流场的控制方程采用有限体积法离散且分离式求解,网格运动的控制方程采用有限元方法离散,网格的分裂采用体和面同时分裂法. 相似文献
7.
给出一种考虑粘件影响的单体复合船型运动预报的数值方法.基于RANS方程和VOF方法的非定常粘性数值方法计算了带叶半潜体的单体复合船型首部横剖面作微幅振荡时的水动力系数.计算中采用RNG κ-ε湍流模型,用有限体积法对流体域进行离散,网格划分采用分块结构化网格,并结合动网格技术.采用RANS方法计算了复合船型组合附体的升力系数.采用计算所得的水动力修正系数,应用STF切片法和二维半理论预报某一单体复合船型在规则波中的纵向运动响应,结果反应出的复合船型的减摇效果与试验值符合较好.计算结果表明组合附体的粘性效应不可忽略,文中提供的方法可提高这类单体复合船型的运动预报精度. 相似文献
8.
9.
10.
11.
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
12.
CFD理论黏性流场中三维振动水翼的非定常水动力性能(英文) 总被引:1,自引:0,他引:1
The motion of the fins and control surfaces of underwater vehicles in a fluid is an interesting and challenging research subject.
Typically the effect of fin oscillations on the fluid flow around such a body is highly unsteady, generating vortices and
requiring detailed analysis of fluid-structure interactions. An understanding of the complexities of such flows is of interest
to engineers developing vehicles capable of high dynamic performance in their propulsion and maneuvering. In the present study,
a CFD based RANS simulation of a 3-D fin body moving in a viscous fluid was developed. It investigated hydrodynamic performance
by evaluating the hydrodynamic coefficients (lift, drag and moment) at two different oscillating frequencies. A parametric
analysis of the factors that affect the hydrodynamic performance of the fin body was done, along with a comparison of results
from experiments. The results of the simulation were found in close agreement with experimental results and this validated
the simulation as an effective tool for evaluation of the unsteady hydrodynamic coefficients of 3-D fins. This work can be
further be used for analysis of the stability and maneuverability of fin actuated underwater vehicles. 相似文献
13.
《船舶与海洋工程学报》2018,(3)
Ship maneuvering in waves includes the performance of ship resistance, seakeeping, propulsion, and maneuverability. It is a complex hydrodynamic problem with the interaction of many factors. With the purpose of directly predicting the behavior of ship maneuvering in waves, a CFD solver named naoe-FOAM-SJTU is developed by the Computational Marine Hydrodynamics Lab(CMHL) in Shanghai Jiao Tong University. The solver is based on open source platform OpenFOAM and has introduced dynamic overset grid technology to handle complex ship hull-propeller-rudder motion system. Maneuvering control module based on feedback control mechanism is also developed to accurately simulate corresponding motion behavior of free running ship maneuver. Inlet boundary wavemaker and relaxation zone technique is used to generate desired waves. Based on the developed modules, unsteady Reynolds-averaged Navier-Stokes(RANS) computations are carried out for several validation cases of free running ship maneuver in waves including zigzag, turning circle, and course keeping maneuvers. The simulation results are compared with available benchmark data. Ship motions, trajectories, and other maneuvering parameters are consistent with available experimental data, which indicate that the present solver can be suitable and reliable in predicting the performance of ship maneuvering in waves. Flow visualizations, such as free surface elevation, wake flow, vortical structures, are presented to explain the hydrodynamic performance of ship maneuvering in waves. Large flow separation can be observed around propellers and rudders. It is concluded that RANS approach is not accurate enough for predicting ship maneuvering in waves with large flow separations and detached eddy simulation(DES) or large eddy simulation(LES) computations are required to improve the prediction accuracy. 相似文献
14.
15.
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
16.
实际海洋环境中舰艇受到多种因素的作用,对舰艇的操纵控制、船舶运动等方面产生了影响.本文基于非规则长峰波的数值仿真,提出舰艇在波浪影响下干扰力的计算方法.从频谱分析角度出发分析舰艇干扰力的主要影响因素,为仿真舰艇在海洋环境下运动提供思路. 相似文献
17.
规则波浪中舰船操纵与横摇耦合运动模拟及特性分析 总被引:2,自引:0,他引:2
采用六自由度舰船操纵性方程与横摇波浪力矩耦合构成动力学模型,对舰船在规则波浪中的操纵与横摇耦合运动特性进行了模拟研究.其中操纵性方程采用MMG模型,波浪力矩由切片法计算,舰船航向按PD控制.模拟计算了某船正横规则波浪下保持航向的横摇运动,计算结果与单自由度理论结果进行了比较,其幅频曲线与相频曲线两者符合较好,间接证明了耦合构成动力学模型的有效性.在此基础上计算了不同浪向角和航速下的横摇运动,以横摇等值极坐标曲线表征舰船规则波浪中的横摇特性,从而给出了规则波浪下舰船耦合动力学所描述的运动特征. 相似文献
18.
应用支持向量机的船舶操纵运动响应模型辨识 总被引:1,自引:0,他引:1
建模是评估船舶操纵性和可控性的重要前提.基于自由自航船模试验的系统辨识方法是求取船舶操纵运动数学模型中的水动力系数的有效手段之一.文中提出了一种使用支持向量回归估计的船舶操纵运动响应模型辨识方法,该方法通过训练自由自航试验数据样本得到参数回归模型.辨识和仿真结果验证了文中所提出的方法的有效性. 相似文献
19.
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