【作者】 王建华；

【导师】 万德成；

【作者基本信息】 上海交通大学 ， 船舶与海洋工程， 2018， 博士

【摘要】 随着高性能计算机的飞速发展以及计算流体力学(CFD)方法的长足进步,采用数值方法研究船舶与海洋工程问题越来越广泛。其中船舶操纵运动,尤其是带螺旋桨带舵船舶的操纵运动数值研究尤为复杂。如果考虑到自航船舶在波浪上的操纵问题,则涉及到了船舶阻力、耐波、推进、操纵等多个方面。该问题是目前国际上最为热点也是最为复杂的船舶水动力学问题之一,同时也是最为接近实际航行船舶的物理问题,因此对该问题的研究有着巨大的科研价值和工程应用前景。采用CFD方法研究船舶操纵运动问题主要受限于几个难点,首先就是自航船舶中复杂的船桨舵耦合运动实现;其次为船舶操纵中的大幅度操纵运动以及不同操纵运动的控制;此外,如果考虑到波浪工况下的自航操纵问题,则需要具备同时进行波浪导致的高频运动和操纵对应的低频运动的求解能力。本博士论文的目的是基于开源代码OpenFOAM,结合课题组开发的包含重叠网格技术的水动力学求解器naoe-FOAM-SJTU,开发船舶自航操纵控制模块,实现船、桨、舵相互作用下的典型船舶操纵运动的数值模拟。同时,对求解器的造波方式进行改造,实现大幅度操纵运动计算中的波浪生成,为自航船舶在波浪工况下的操纵问题数值研究提供了一个有效可行的方案和工具,进而将自航船舶操纵运动的数值研究从静水工况扩展到波浪工况中。操纵运动控制模块开发中,本文在求解器多级物体运动模块的基础上完成了不同操纵试验中所需的舵角控制器设计工作。基于重叠网格技术的多级物体运动概念,采用运动反馈机制,完成了船舶航向保持、Z形操纵和自由回转操纵试验的舵角控制模块开发和完善,进而实现了自航船舶典型操纵运动的直接数值模拟。针对波浪中船舶的操纵运动问题,文中通过将原有的水动力学求解器naoeFOAM-SJTU与开源造波工具包waves2Foam相结合,充分利用waves2Foam造波方法中的基于松弛方法的区域造波形式,解决了计算域移动过程中所面临的数值造波问题。扩充造波功能后的求解器能够进行在规则波浪工况下带螺旋桨带舵船舶操纵运动的直接数值模拟。为了验证基于重叠网格技术的求解器在处理船舶大幅度操纵运动,以及自主开发的自航船舶操纵控制模块和造波模块处理带螺旋桨带舵船舶在静水和波浪中操纵运动问题时的能力,本文进行了船舶平面运动机构试验数值模拟、静水中船舶典型操纵运动和波浪工况下的自航操纵运动的直接数值模拟三部分的算例验证。第一部分是针对标准船模DTMB 5415平面运动机构试验(PMM)的数值模拟研究。利用重叠网格实现船舶的大幅度平面运动,计算获得PMM操纵运动过程中的船舶水动力系数。通过与试验结果的对比,验证了当前的动态重叠网格技术在处理大幅度船舶运动中的可靠性。第二部分为静水工况中带螺旋桨带舵船舶的自航操纵运动直接数值模拟。数值验证算例包括全附体双桨双舵ONRT船模的标准10/10、20/20 Z形操纵试验和35°舵角自由回转操纵试验的数值模拟。第三部分为波浪工况下的自航船舶操纵运动直接数值模拟,验证算例包括ONRT船模在迎浪、首斜浪和横浪三种规则波工况下的航向保持数值模拟;不同波长、波高工况下的标准10/10 Z形操纵运动数值模拟;规则波下35°舵角自由回转操纵运动数值模拟。所有算例均采用重叠网格方法进行船体、螺旋桨和舵的网格划分,并且通过运动反馈机制进行相应的操纵运动控制。数值验证算例均有模型试验数据进行验证和对比分析,数值结果可以较为准确的预报出船舶的操纵运动特性,充分验证了当前的基于重叠网格技术开发的操纵控制模块在处理自航船舶操纵问题上的有效性和可靠性。同时,根据波浪工况下的船舶自航操纵运动直接数值模拟可以看出,目前的方法可以为规则波环境下的船舶操纵性研究提供一个有效的途径,大幅度地扩展了当前CFD方法在船舶水动力学方面的应用范围。更多还原

【Abstract】 With the boosting of high performance computing and developments of numerical methods,Computational Fluid Dynamics(CFD)has been widely used in the research field of naval architecture and ocean engineering.Among several concerned hydrodynamic problems,ship maneuveriability is one of the most complex problems in the research of ship hydrodynamics.When considering ship maneuver in waves,it becomes the one of the most challenging issues since it involves the performance of ship resistance,propulsion,seakeeping and maneuvering.In general,it is very close to the real world condition and making it with a great prospect for the applications in ship and ocean engineering.So far,the most challenging problems are as follows: first is the complex coupling motion with the ship hull-propeller-rudder system,another one is the maneuvering control and large amplitude motions,as for maneuvering in waves,the tool should have the ability to solve the low frequency maneuvering motion and high frequency wave induced motion simultaneously.The objective of this dissertation is to develop the maneuvering control module based on the in-house code naoe-FOAM-SJTU,with the purpose of extending its ability in simulating various ship maneuvers.In addition,this paper has also modified the wave generation module,which makes it possible to numerically investigate the self-propelled ship maneuver in waves.Within the implementation of maneuvering control module,the paper adopts a feedback control mechanism with respect to the ship motion.Based on the overset grid technology,heading control,zigzag and turning circle maneuver control module are developed to directly simulate the free running ship maneuver.As for the wave generation module,the paper have combined the present naoe-FOAMSJTU solver with the open source third-party wave generation tool waves2 Foam,which can make full use of the relaxation zone and can generate desired waves with moving computational domain.So far,it has been proved to be reliable and robust in simulating ship maneuver in regular waves.In order to validate the developed maneuvering control module and improved naoeFOAM-SJTU solver,three categories of validation cases including planner motion mechanism(PMM)tests,free running ship maneuver in calm water and various waves are performed.The first validation case is the simulation of PMM tests,where the static drift,pure sway and pure yaw test are computed.Through the static and dyanmic test,the solver is proved to be reliable in simulating the large amplitude maneuvering motion.The second category is the self-propelled ship maneuvers with direct rotating propellers and moving rudders.The fully appened twin screw ONR Tumblehome ship model is used for the selfpropulsion calculation and the free running maneuver in calm water.In the free running maneuver in calm water case,standard 10/10,20/20 zigzag maneuver and turning circle maneuver are performed.In the third category,the free running ship maneuver in regular waves are directly simulated.The validation cases include the course keeping simulations in head waves,bow quartering waves and beam waves,as well as the free running ship zigzag maneuver in various wave conditions,where different wave length and wave heights are calculated to investigate the wave effects on the free running ship maneuver.Turning circle maneuver in waves is also investigated.The rudders and propellers are fully discretized by overset grids in all the validation cases.These rotating propellers and moving rudders are able to move with respect to the ship motions and itself can move according to the specified maneuvering control.The numerical results of the maneuvering parameters are compared with the available experiment measurements and the comparisons show good agreements,which indicate that the present developed maneuvering control module and the wave module can be reliable and robust in handling with free running ship maneuver in both calm water and regular waves.The application areas in ship hydrodynamics have been greatly expanded using the present numerical approach.更多还原