扁平潜器微速与倒航水动力试验研究

在长条水池中进行了具有扁平外形潜器的微速与倒航运动的水动力模型空间斜拖试验，测量了具有攻角和漂角同时存在下的空间运动的三个水动力和三个水动力矩。将测量的水动力和力矩整理成空间角度攻角、漂角的变化关系曲线图，初步得到了其变化规律。最后将水动力和力矩回归成攻角和漂角双变量的表达式。     

带空泡运动航行体的附加质量研究

提出了确定带自然空泡运动物体附加质量的方法.这一方法基于在数值水洞中作摇荡运动物体的水动力计算, 包括两个主要步骤:首先采用CFD技术模拟空泡流场,求解水动力;然后根据物体运动方程,由水动力计算出附加质量.研究了带自然空泡圆盘和轴对称细长体的附加质量.计算结果与理论解一致,验证了本文方法的有效性.与切片法相比,本文方法可以更为准确地定量预报带空泡运动轴对称细长体的附加质量.     

Hydrodynamic behaviour of European black poplar (Populus nigra L.) under coppice management along Mediterranean river ecosystems

This study examined the hydrodynamic behaviour of European black poplar (Populus nigra L.) under coppice management in riparian areas with a multidisciplinary approach. An innovative procedure on the basis of the combination of plant allometric relations and hydrodynamic models was applied to assess drag forces and plant hydrodynamic bending as function of the basal diameter and module of elasticity, with a probabilistic approach. Cuttings of European black poplar from 2 close riverine environments of Southern Italy have been planted and subjected to the same coppice management strategy. The 2 different 3‐year‐old shoot poplar ensembles exhibited statistically similar morphological traits but stems with different module of elasticity. Drag forces were simulated with a model on the basis of the vegetative Cauchy number. Plant deformation under the hydrodynamic load was modelled as a base‐mounted cantilever beam. The differences in the observed elasticity were verified to be also significant from a hydrodynamic perspective. Diagrams were drawn to describe plant bending, drag forces, and basal momentum as function of basal diameter, accounting for the uncertainty in the module of elasticity. These results can be exploited for identifying objective hydrodynamic criteria to be adopted for coppice management of riparian woody vegetation in human controlled river ecosystems.     

STUDY OF HYDRODYNAMIC FORCES OF SHIPS IN NARROW WATERWAY

1 .　INTRODUCTIONInrestricatedwaterssuchasnarrowwater ways,itisnecessarytoknowthemaneuveringcharacteristicsofships .Thecollisionofshipsisoneofthemajorreasonsofshipwreckintheworld .Thecollisionsmayoccurforavarietyofreasons .Theymaybedue ,amongotherthings ,tohumanerror ,mechanicalfailure ,weatherandwa terconditions .Butthehydrodynamicforcesbe tweentwoshipsandbetweenshipandbank ,theeffectofdepthofwateralsochangethemaneuver ingcharacteristicsofshipsgreatly .Innarrowwa terways ,specially ,the…     

THE RADIATION AND DIFFRACTION OF WATER WAVES BY A BOTTOM-MOUNTED CIRCULAR CYLINDER IN A TWO-LAYER FLUID

An analytical method was proposed to analyze the radiation and diffraction of water waves by a bottom-mounted circular cylinder in a two-layer fluid. Analytical expressions for added mass and damping coefficients, as well as the wave excitation forces of the circular cylinder were obtained by an eigenfunction expansion method. The hydrodynamic forces on the bottom-mounted circular cylinder in a two-layer fluid include not only the added mass and damping coefficients, but also the wave forces of the surface and internal-wave modes. This is different from the case of a homogenous fluid. Some examples were given, showing that density stratification can have a relative large effect on these hydrodynamic forces over a wide range of frequencies.     

Numerical prediction of hydrodynamic forces on a ship passing through a lock with different configurations简

A CFD method is used to numerically predict the hydrodynamic forces and moments acting on a ship passing through a lock with a constant speed. By solving the RANS equations in combination with the RNG k-e turbulence model, the unsteady viscous flow around the ship is simulated and the hydrodynamic forces and moments acting on the ship are calculated. UDF is com-piled to define the ship motion. Meanwhile, grid regeneration is dealt with by using the dynamic mesh method and sliding interface technique. Under the assumption of low ship speed, the effects of free surface elevation are neglected in the numerical simulation. A bulk carrier ship model is taken as an example for the numerical study. The numerical results are presented and compared with the available experimental results. By analyzing the numerical results obtained for locks with different configurations, the influences of approach wall configuration, lock configuration symmetry and lock chamber breadth on the hydrodynamic forces and moments are demonstrated. The numerical method applied in this paper can qualitatively predict the ship-lock hydrodynamic interaction and pro-vide certain guidance on lock design.     

A TIME DOMAIN INVESTIGATION ON THE HYDRODYNAMIC RESO-NANCE PHENOMENA OF 3-D MULTIPLE FLOATING STRUCTURES

A 3-D time domain method is developed to investigate the gap influence on the wave threes for 3-D multiple floating structures. Special hydrodynamic resonance due to small gaps between multiple floating structures on wave forces is examined. Strong and complicate hydrodynamic interactions between the floating bodies are observed and the numerical computations have proved the existence of the sharp peak force response on each floating body at some special resonant wave numbers. By comparison with the results from the frequency domain technique, the results obtained from the time domain method reveal the similar resonant phenomena and hydrodynamic interaction. The resonant wave numbers are also proved around kL-nπ （n = 1,2 ……∞） with a corresponding frequency shift. The strong hydrodynamic interaction feature is practically significant for the design of module structures and the links （connection） in whole the floating body system.     

COMPUTATION OF HYDRODYNAMIC INTERACTION FORCES BETWEEN SHIPS BASED ON B-SPLINES

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｉｎｔｈｅａｓｓｕｍｐｔｉｏｎｏｆｓｌｅｎｄｅｒ ｔｈｅｏｒｙ ,Ｙｅ ｕｎｇ[1 ,2 ] ｆｉｒｓｔｒｅｃａｓｔｔｈｅｔｈｒｅｅ ｄｉｍｅｎｓｉｏｎａｌｐｒｏｂｌｅｍｏｆｔｗｏｓｈｉｐｓｍｏｖｉｎｇｉｎａｓｈａｌｌｏｗｆｌｕｉｄｉｎｔｏｔｗｏｉｎｎｅｒｐｒｏｂｌｅｍｓａｎｄｏｎｅｏｕｔｅｒｐｒｏｂｌｅｍａｎｄｄｅｒｉｖｅｄａｐａｉｒｏｆｃｏｕｐｌｅｄｉｎｔｅｇｒａｌ ｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｓｆｏｒｄｅｔｅｒｍｉｎｉｎｇｔｈｅｕｎｋｎｏｗｎｃｒｏｓｓ ｆ…     

大直径多圆柱体近海结构上的二阶辐射水动力

本文提出了一种解析方法，用来研究由海底地面动力激励引起的大直么径双圆柱体上的二阶辐射水动力问题，文中分析了激励频率和柱距等因素对二阶水动力的影响，将二阶水动力的各组成部分做了比较，还将二阶水动力与一阶水动力作了对比，并由此得出了有意义的结论。     

NONLINEAR DIFFRACTION FORCES ON LARGE MULTICYLINDRICAL OFFSHORE STRUCTURES

ＮＯＮＬＩＮＥＡＲ　ＤＩＦＦＲＡＣＴＩＯＮ　ＦＯＲＣＥＳ　ＯＮ　ＬＡＲＧＥ　ＭＵＬＴＩＣＹＬＩＮＤＲＩＣＡＬ　ＯＦＦＳＨＯＲＥ　ＳＴＲＵＣＴＵＲＥＳＮＯＮＬＩＮＥＡＲＤＩＦＦＲＡＣＴＩＯＮＦＯＲＣＥＳＯＮＬＡＲＧＥＭＵＬＴＩＣＹＬＩＮＤＲＩＣＡＬＯＦ...     

波流作用下海底管道的水动力和在位稳定性研究的近代进展

近年来，随着海上油、气田的相继开发，海底管道作为输送近海油、气产品至岸上终端这样的连续结构物，其工程地位十分重要，国内外建设的数量是与日剧增。海底管道设置在恶劣的海洋环境中，将承受各类环境载荷，其中流、流引起的水动力载荷最为重要。对海底管道这样的海洋工程，保证其正常运行和结构自下而上期的安全，是直接与海底管道所受的水动力及其在位稳定性密切相关的。     

HYDRODYNAMIC INTERACTIONS BETWEEN TWO BODIES

On the basis of model tests, potential flow theory, and viscous Computational Fluid Dynamics (CFD) method, the hydrodynamic interactions between two underwater bodies were investigated to determine the influencing factors, changing rule, interaction mechanism, and appropriate methods describing them. Some special phenomena were discovered in two series of near-wall interaction experiments. The mathematical model and predicting methods were presented for interacting forces near wall, and the calculation results agreed well with the experimental ones. From the comparisons among numerical results with respect to nonviscosity, numerical results with respect to viscosity, and measured results, data on the influence of viscosity on hydrodynamic interactions were obtained. For hydrodynamic interaction related to multi-body unsteady motions with six degrees of freedom that is difficult to simulate in tests, numerical predictions of unsteady interacting forces were given.     

地震对海底悬跨管道动水力作用的实验研究

利用水下地震模拟系统,开展了刚性管道在地震作用下的水下模型实验,量测了管道周围流场的变化和管道表面的动水压力.基于Morison方程建立了地震作用下海底悬跨管道的动水作用力模型,按最小二乘原理得出管道的拖曳力系数C_D和惯性力系数C_(M°)通过对实测数据分析得出,雷诺数Re数和K_c数是影响管道受力的两个主要因素.分别对C_D和C_M随Re和K_c的变化趋势进行了拟合,得到C_D和C_M的定量表达公式.本次试验工况下,水深和悬跨高度对管道的受力影响不明显.     

Wave radiation and diffraction by a floating rectangular structure with an opening at its bottom in oblique seas

The radiation and the diffraction of linear waves by a rectangular structure with an opening at its bottom floating in oblique seas of finite depth are investigated. Analytical expressions for the radiated potentials and the diffracted potential are obtained by use of the method of separation of variables and the eigenfunction expansion method, with the unknown coefficients being determined by the boundary conditions and the matching requirement on the interface. The hydrodynamic coefficients and the wave excitation forces are verified using the symmetry properties of coupled hydrodynamic coefficients and one specific example investigated previously. By use of the present analytical-numerical solution, the influences of the angle of incidence, the width of the opening on the wave forces and the hydrodynamic coefficients are investigated. It is also found that in the oblique sea the external excitation frequency that can lead to the resonance of a rectangular tank depends on the wave direction and the wave number of the incident wave.     

WAVE FORCES ON INCLINED CYLINDER IN REGULAR WAVES

Through a series of model tests,the wave forces on horizontal and inclined circularcylinders are measured and analyzed.Based on Morison Equation and Stokes second order wavetheory,the relationship between the hydrodynamic force coefficients with KC number and sub-merged water depth as well for horizontal cylinders are analyzed,also the relationship betweenthe hydrodynamic force coefficients with KC number,inclined angle and the effect of water freesurface as well for the inclined cylinders are investigated.     

The hydrodynamic interactions of an array of truncated circular cylinders as each cylinder oscillates independently with different prescribed modes

An analytical method based on the eigenfunction expansion and the Graf’s addition theorem for Bessel functions is developed to study the hydrodynamic interactions of an array of truncated circular cylinders with each cylinder oscillating independently in different prescribed modes. The hydrodynamic radiation and diffraction of linear waves by such an array of cylinders are investigated and the analytical solutions of the velocity potentials are obtained. After comparisons for degenerated cases and program verifications, several cases for an array of truncated cylinders with each cylinder oscillating independently in surge, sway, heave, roll, and pitch modes with different prescribed amplitudes, are studied and the hydrodynamic forces and moments acting on the cylinders are obtained.     

基于重叠网格技术数值模拟船舶纯摇首运动

该文采用基于非定常RANS方程的黏性数值模拟方法,对标准船模DTMB5512裸船体在平面运动机构(PMM)控制作用下的纯摇首运动进行了数值模拟。文中数值计算采用基于开源CFD工具包Open FOAM和重叠网格技术开发的多功能水动力学求解器naoe-FOAM-SJTU。根据SIMMAN2014提供的标准算例,对同一运动频率下,在Fn=0.28工况下的3种不同运动幅值的纯摇首运动进行了数值计算,得出了船舶不同工况下的阻力、侧向力和转首力矩的历时曲线。并且根据操纵性数学模型(MMG)推导出相应的水动力导数值,所有计算结果同模型试验数据吻合较好,验证了采用当前处理方法数值求解纯摇首运动的可靠性。     

基于CFD的船-舵水动力干扰数值研究

该文采用基于RANS方程求解的CFD方法,对匀速直航的船-舵系统的黏性绕流场进行数值模拟,计算了不同船速和不同舵角下的船-舵水动力干扰系数,计算中忽略了自由面兴波及螺旋桨的影响。文中以KVLCC1船、舵模型为研究对象,首先将数值计算的船舶水动力及船-舵水动力干扰系数结果与模型试验数据进行比较,验证了所采用数值方法的有效性;随后,对船-舵系统、裸船体和敞水舵分别进行计算,通过水动力计算结果的比较以及流场分析,对船-舵水动力相互作用进行了数值研究。     

小攻角带空泡细长体的试验研究

本文对小攻角带空泡细长体进行了较为细致的试验研究。其中包括水洞三分力天平的研制与测力系统的建立，空泡起始、发展空泡形态观测，空泡几何特征的测量和定常来流中空泡水动力的测量，对试验结果进行深入的研究和分析，以揭示其中某些内在的规律性，同时为进一步的研究提供经验。     

等效网面法在模拟网的水动力特性中的应用

采用有限单元法建立了网状柔弹性结构的等效网面动力模型。通过把一系列杆相互无摩擦铰接在一起,建立起网结构。采用Morison公式计算作用在杆上的水动力。利用网目合并的方法来减少总的自由度数目。为了验证模型的正确性,数值模拟的结果同前人的试验结果进行了比较,效果良好。