船舶航行条件的实时模拟

简要介绍了船舶航行条件实时模拟的基本原理和船舶操纵运动数学模型及实时算法。通过某工程双线船闸下游引航道进闸航行条件的实时模拟,说明了应用实时模拟研究航道航行条件的方法和步骤。     

高速横流作用下内河船舶偏转状态研究

我国内河航道是世界上运量最大、运输最繁忙、通航条件最复杂的航道之一，而横流是影响船舶安全通航的重要因素，目前国内外学者主要分析低速横流对船舶航行的不利影响，但对船舶在高速横流作用下运动情况研究较少。为揭示高速横流对内河船舶的影响，并对高速横流在航道中的整治利用进行可行性分析，通过数值模拟和概化模型试验，观察高速横流下船舶的运动形态以及不同喷射口压强，不同船－墩间距对船舶偏转的影响。结果表明:高速横流可以在桥墩前方形成弧形干扰带，拨开船艏，实现船桥避碰；船舶经过高速横流时依次经历船身顺直前进、船艏向远离桥墩偏转、船身回正、船尾向远离桥墩方向偏转四个阶段；喷射口压强越大，相同船－墩间距下船舶艏向角峰值越大，船舶到达艏向角峰值处位置越靠前，船身回正所用距离越短；船－墩间距越远，相同喷射口压强下船舶艏向角峰值越小。     

弯曲航道通航宽度和水流条件确定方法探讨

为消除因地形和水流条件等因素限制了弯曲航道尺度,导致船舶航行不安全的隐患,通过调研,整理分析了全国主要通航河流各等级航道弯曲航道情况,对弯曲航道影响船舶航行的因素进行了总结分析。采用弯曲航道概化模型试验和弯曲航道遥控船模试验,结合已有研究成果和有关标准及规范,研究不同弯曲半径的弯曲段航道宽度,提出了适用于不同航道等级内河弯曲航道通航尺度的确定方法;初步探讨了弯曲航道水流条件,提出了弯曲航道通航水流条件技术要求的确定方法。为内河水运工程建设、航道治理、维护标准的确定提供技术支持和科学依据。     

葛洲坝大江下航道水流条件分析

航道水流条件是保证船舶航行安全的主要问题之一。葛洲坝大江下游引航道由于受枢纽泄洪影响，航道内存在明显的泄水波和高流速区，造成船舶航行困难，影响安全。因此，现行船舶只在流量２００００ｍ＾３／ｓ以下通行。为此，近年来，对原型水流条件作了大量观测，探讨提高通航流量的可能性。经分析认为，在现行条件下，通航流量可提高到２３０００ｍ＾３／ｓ。     

航道工程中的浮泥研究综述

对浮泥层的定义,船舶航行对浮泥的影响及浮泥对航道工程的影响进行了分析,指出浮泥层对航道适航水深的确定和航道回淤量计算的影响较大。由于浮泥的成因和运动规律复杂,影响因素众多,浮泥对航道工程的影响研究有待于深入。     

船舶航行对河床底泥扰动影响的验证方法浅析

在一定的水深条件下，船舶螺旋桨在航行过程中产生的射流会对河床底泥产生扰动影响，该扰动作用能否引起河床底泥的再悬浮有待进一步研究分析。以余杭塘河典型航段为研究对象，前期通过静力触探试验发现河床底泥状态较为稳定，在载重型船舶航行前、后的时间窗口，利用NORBIT iWBMS多波束测深系统对该航段进行跟踪测量。测量结果表明，在目前水深条件下，载重型船舶螺旋桨射流难以引起河床沉积底泥起动和再悬浮，初步可以判断船舶正常航行在该航道时对河床底泥影响不显著。     

三峡船闸运行过程仿真方法研究

本文首先阐述了三峡船闸进行模拟的必要性，分析了三峡船闸的运行特点，提出须同时对船闸输水过程和船舶过闸过程进行仿真，建立了模拟船闸输水过程水力特性及航道水流的仿真数值模型；提出采用船舶模拟器进行船舶航行过闸仿真模拟的方法，最后介绍了所研制的船舶模拟器的功能及组成。     

山区河流船舶实航线路影响因素分析

在内河船舶标准化和大型化快速发展的背景下,航道设计规范与通航代表船型不相符导致航道等级与航道通航能力不协调,从而引发船舶碰撞、搁浅、触礁等恶性事件发生。通过收集长江上游复杂航道的水文、地形和船舶航行资料,利用二维水流数模型对研究河段水流进行模拟,明确了长江上游复杂通航河段的地形条件、水动力特征、通航现状及碍航机理。根据航道规范和理论计算,对长江上游航道宽度、水深、弯曲半径和流速-比降组合值对应的船舶上滩指标进行计算、分析和评价,得到了研究河段对应的规范设计尺度。     

万安水利枢纽施工期临时通航设计

在通航河道上建造水工建筑物时,由于分期导流围堰束窄河床或完全截断河床、或者在河床中挖取砂石骨料,均会改变河床流速、流态,引起新的激烈地造床运动,招致航道变迁;施工船舶占据航道且航行频繁,     

Mike21软件在航道通航条件影响评价中的应用

为了评价226省道九圩港大桥工程建设对航道通航条件的影响,文章通过Mike21二维模型模拟了航道引水、排水两种情况下桥梁建设对航道通航条件的影响。根据模拟结果,水流在桥墩、导航桩、防撞桩附近会产生绕流,导致桥区出现横向水流,但是横向流速大于0.3 m/s的横流宽度较小,对船舶的航行安全影响不大。     

基于相空间重构技术的舰船摇荡极短期预报

舰船运动受各种非线性因素影响严重,且舰船自身6个自由度的运动间存在相互耦合,在很多情况下表现为混沌。本文提出了基于相空间重构技术的舰船摇荡极短期预报模型,包括加权一阶局域法多步预报模型和RBF神经网络局域法多步预报模型。仿真表明,两种模型均能有效预报舰船摇荡极短期运动。     

SIMULATION OF TANK SLOSHING BASED ON OPENFOAM AND COUPLING WITH SHIP MOTIONS IN TIME DOMAIN

Tank sloshing in ship cargo is excited by ship motions, which induces impact load on tank wall and then affects the ship motion. Wave forces acting on ship hull and the retardation function are solved by using three-dimensional frequency domain theory and an impulse response function method based on the potential flow theory, and global ship motion is examined coupling with nonlinear tank sloshing which is simulated by viscous flow theory. Based on the open source Computational Fluid Dynamics (CFD) development platform Open Field Operation and Manipulation (OpenFOAM), numerical calculation of ship motion coupled with tank sloshing is achieved and the corresponding numerical simulation and validation are carried out. With this method, the interactions of wave, ship body and tank sloshing are completely taken into consideration. This method has quite high efficiency for it takes advantage of potential flow theory for outer flow field and viscous flow theory for inside tank sloshing respectively. The numerical and experimental results of the ship motion agree well with each other.     

非线性横摇运动的摄动解

本文描述了船舶在突风及规则波共同作用下的非线性横摇运动方程。讨论了当波浪周期接近于船舶自由横摇固有周期时，其非线性方程的多重尺度解法，并应用李雅普诺夫稳定性理论，讨论了方程的稳定性。     

Effect of internal sloshing on added resistance of ship

The motion responses of ships carrying liquid cargo are affected not only by external wave excitation, but also by internal sloshing-induced forces and moments. Sloshing flow is coupled with the ship motion. This means the added resistance in waves may change when sloshing occurs inside the tank of the ship. In this study, the motion responses and added resistance of a ship, coupled with the sloshing-induced internal forces and moments are considered by using the linear potential theory. The three-dimensional Rankine panel method, in which the physical quantities are represented by using B-spline basis function, is applied. The sloshing flow of inner tanks is also simulated by using the Rankine panel method and linearized boundary value problem. To study the added resistance, a near-field method, which integrates the second-order pressure on a body surface, is applied. The model ship is a blunt modified Wigley model with two inner tanks. Numerical results obtained without inner tanks are compared with the experimental data, and then the effect of filling ratio of inner tanks on ship motion and added resistance are observed. The components that induce added resistance are examined, and the effects of surge motion on sloshing flow and added resistance are briefly considered. This study shows that the sloshing flow inside the inner tanks may significantly influence not only the motion responses, but also added resistance, especially, when the incident wave frequency approaches the resonance frequency of the sloshing flow.     

船舶线性耦合运动稳定性

本文讨论了船舶线性非时变系统及线性时变系统运动的稳定性。对线性非时主系统，本文给出了船舶运动稳定性的这例，及其数学物理上对这类问题稳定性的判别法，对线性周期时变系统，文中对于两种稳定性判别法及其近似解法作了讨论和比较，两种判别法分析为李雅普诺夫直接法及特征根判别法。     

浅窄航道会遇船舶水动力相互作用数值计算

该文应用CFD软件对两船在浅窄航道中会遇时的水动力相互作用进行数值研究,通过求解非定常RANS方程并结合RNG k-ε湍流模型,采用动网格技术及UDF进行船舶运动过程中的网格更新,对两船沿平行直线航行时的三维非定常黏性流场进行数值模拟,并对其相互作用水动力进行了计算。首先通过计算结果与试验数据进行对比,验证了数值方法的可行性和有效性;随后对四种船型在不同水深、航道宽度、两船航速比和船-船横向间距下的水动力进行了系列计算,通过结果分析得出了以上因素对两船会遇水动力相互作用的影响规律。     

Stability of a tumblehome hull under the dead ship condition

Some methods for direct stability assessment under the dead ship condition were currently developed by the international maritime organization(IMO)under the Second Generation Intact Stability Criteria.Model tests and simulations are carried out to validate the numerical methods used in assessing the stability under the dead ship condition.This is done in three stages.Firstly,the uncoupled roll mathematical model(1 DOF)is adopted to calculate the roll motion based on the irregular beam waves and the steady wind.Secondly,a drift free experiment is conducted to measure the roll motion under irregular beam waves with zero speed,and then two restrained experiments with counter weights and four springs are performed under the same condition.Finally,the effects of the drift and sway motions on stability under the dead ship condition are then verified by experimental results,and the results of the numerical methods are compared to the results of the model experiments.It is concluded that more accurate numerical methods could be developed for assessing the direct stability under the dead ship condition.     

波浪周期对系泊船舶运动影响试验研究

系泊船舶泊稳是港口设计和营运过程中的重要问题,系泊船舶泊稳标准从实质上讲就是限制系泊船舶的运动量。较长周期波浪作用下的系泊船舶泊稳问题愈来愈受到各方的关注,选取了一艘10万吨级散货船进行横向不规则波作用下的系泊模型试验,在同一波高下变化入射波浪周期,通过系列试验,分析波浪周期对系泊船舶横移、横摇和升沉运动的影响。研究结果表明,系泊船舶横移运动量总体上均随着波浪周期的增大而增大,横移运动对波浪周期的响应敏感程度是变化的;系泊船舶横摇和升沉运动量均随着波浪谱峰周期的增大先增大然后减小,当波谱谱峰周期与相应的船舶固有周期接近时,横摇和升沉运动量均出现了一次峰值。     

横摇非线性方程的研究

本文对横摇运动的非线性方程的求解引入两种方法:迦辽金法和Cell—to—Cell映射法。同时对迦辽金法求得的解进行了稳定分析。通过对“长江口交通补给船”在规则波的运动进行计算,并把结果与试验结果作了比较,总的说来还比较一致。