船过船闸时的水动力特性数值预报研究

When a ship sails in a lock its navigation environment is very complicated. The hydrodynamic phenomenon of shallow water effect, bank effect, etc. arise due to the interactions from the lock structure or other structures, thus there are interaction forces acting on the ship, which threaten the security of ship and lock. This project intends to study a sliding grid approach and a method of numerical simulation of 6 Degree of Freedom (DoF) ship motions based on the open source computational fluid dynamics software OpenFOAM, addressing the technical issues of the interpolation algorithm for fluid information exchange between relative sliding grid blocks, the method to deal with both ending boundaries of moving grid region, the method to solve the coupling equations of Averaged-Reynolds Navier-Stokes (RANS) and ship motion, and so on, thus achieve the goal of studying the hydrodynamic performance for a ship in a lock based on OpenFOAM. Appling the new developed numerical tool, the three gorge lock is taken as an example to simulate the ship motion under typical working conditions, so as to study the influence rules of ship speed, ratio of water depth to draft, eccentricity, lateral distance between ships etc. on ship hydrodynamics. Also the influences of different lock structures on ship hydrodynamics and the acting mechanisms of shallow water effect under the condition of extremely small water depth and bank effect under the condition of extremely small distance from wall are studied. The study of this project can give technical support to ship navigation safety in a lock and optimization design of lock, and has important application value.

船过船闸时的航行环境非常复杂，受船闸结构物或其它结构物的影响，会产生浅水效应、岸壁效应等水动力学现象，使船受到干扰水动力作用，威胁到船和船闸的安全。本项目拟基于开源计算流体动力学软件OpenFOAM，研究一种滑移网格方法以及船舶6自由运动数值模拟方法，解决相对滑移网格块之间流体信息交换插值算法、动网格区域两端边界处理方法、耦合求解雷诺平均纳维-斯托克斯（RANS）方程和船舶运动方程的方法等关键问题，从而实现船闸水域船舶水动力特性的研究。应用新开发的数值工具，以三峡船闸为研究对象，模拟船过船闸时的典型工况，研究船速、水深吃水比、偏心距、船-船横向距离等因素对船舶水动力的影响规律。同时，研究不同船闸几何结构形式对船舶水动力的影响以及在极浅水深条件下浅水效应和在极小船到墙壁距离条件下岸壁效应的作用机理。本项目的研究可为船闸水域船舶的安全航行以及新建船闸的优化设计提供技术支持，具有重要的应用价值。

船闸水域，浅水效应、岸壁效应、及其它交通船只干扰等是影响船舶航行安全的重要因素，对船舶操控性能提出更高要求。基于OpenFOAM，研发RANS求解器，计算船舶深、浅水操纵运动水动力，回归分析计算结果，确定水动力导数，通过求解运动方程，仿真船舶自航模操纵运动，分析浅水对操纵性的影响，表明：深水仿真结果与试验数据吻合良好，RANS计算及运动模型精度较高；水深变浅，船舶回转性变差（回转圈直径变大），航向稳定性变好（超越角变小、转向滞后时间变短）。为验证新研发耦合求解船舶运动方程和RANS方程模块，以KCS、KVLCC2、DTMB 5415为对象，计算船舶迎浪直航动力响应，计算结果与试验数据吻合良好。基于商业软件Star CCM+，采用重叠网格方法，数值模拟船舶追越过程，分析船-船相对位置对干扰水动力影响，表明：追越过程中，两船皆出现吸引-排斥-吸引现象，在纵向距离小于半个船长范围内，横向力和转首力矩达到最大值，两船处于较危险状态。基于Fluent，数值模拟船过巴拿马运河第三组船闸过程，计算结果与试验数据吻合良好，流场分析表明：随着船体一侧航道截面逐渐收缩，收缩一侧流速变大，改变船体表面压力分布，船舶受到较大横向力，产生岸吸现象。以三峡船闸为对象，数值模拟船驶入升船机船厢过程，分析船舶水动力特性，表明：当船驶入下闸首，过渡引航道截面逐渐收缩，阻力缓慢增大，横向力迅速增大；当船部分进入船厢，水深迅速变浅，阻力快速增大，半个船体进入船厢时，横向力达到最大值；当船逐渐靠近厢门出口，阻力开始减小，横向力亦开始减小并逐渐趋于零。通过研究，拓展OpenFOAM功能，可为船舶水动力性能研究提供分析工具；研究分析船舶追越干扰水动力、船进船闸过程水动力特性，可为船舶安全驾驶和航道设计提供科学依据；对三峡升船机航道中船舶水动力性能研究，可为相关部门科学管理,提高过坝效率提供参考。