【作者】 郭宇；

【导师】 胡安康；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋结构物设计制造， 2013， 博士

【摘要】 随着我国船舶工业的迅速发展，船舶与海洋结构物日渐趋于大型化和复杂化，这对阴极保护系统的防护有效性也提出了更高的要求。因而寻求实用有效的船舶与海洋结构物阴极保护电位预报与优化设计方法对船舶与海洋工程的发展具有重要意义。在传统的阴极保护工程设计中，大多采用实际测量或经验估计来获得保护电位分布。实际测量虽然直观、可靠性高，但由于时空、环境等因素的限制往往施工困难，费用昂贵，依靠经验估计也在某种程度上不能保证结果的准确性。近年来计算机的出现和数值仿真技术的兴起，为科学预报、评估和优化船舶与海洋结构物阴极保护系统提供了全新的技术手段。数值仿真方法具有快捷、经济、获得数据全面、结果直观等优点，因此本文研究船舶与海洋结构物的阴极保护电位数值仿真和优化设计具有重要的理论意义和工程实用价值。本文首先研究了应用传统公式进行船舶与海洋结构物阴极保护方案的初步设计方法。根据船舶与海洋结构物结构特点、营运环境和材料的电化学特性，选取阴极保护方法和主要设计参数——保护电位和保护电流密度，由结构图纸或计算公式得出保护面积，进而确定辅助阳极或牺牲阳极的类型和数量，最终得出满足腐蚀防护目标要求的阴极保护初步方案。为后续章节的阴极保护电位数值仿真和优化设计奠定基础。本文采用三维边界元方法求解阴极保护数学模型，通过引入分段拟线性化方法处理边界条件的非线性问题，建立线性方程组并求解，最终应用FORTRAN语言实现自主开发阴极保护电位数值仿真软件。该软件克服了以往商业软件中存在的仿真模型建立方式唯一和模型不具有通用性的缺陷，仿真结果输出形式多样，可对多种阴极保护方法的保护电位进行数值仿真，便于操作和工程实际应用。通过将软件计算结果与实验值比较，验证了软件计算方法的可行性和计算结果的准确性。应用该软件对本文设计的9200TEU集装箱船外加电流阴极保护系统和400ft自升式钻井平台牺牲阳极阴极保护系统的保护电位进行仿真预报，可得出详细准确全面的电位分布计算结果。本文根据工程实际应用经验，提出仿真计算的建模流程和边界条件设定方法。在9200TEU集装箱船外加电流阴极保护电位仿真过程中，采用在极化曲线中保持电位不变，改变电流密度的方法实现模拟涂层破损率。在400ft自升式钻井平台牺牲阳极阴极保护电位仿真过程中，采用分块边界元方法解决计算中电解质不一致问题，提出分区域建模方法解决电解质不连续问题，通过将模型整体电位分布计算中获得的内面电位值作为边界条件加载到计算结构相贯区域电位分布模型中相对应的内面节点上，得到自升式平台复杂节点保护电位分布。分析计算结果得出：400ft自升式钻井平台牺牲阳极阴极保护初步方案合理可行，9200TEU集装箱船外加电流阴极保护初步方案还需进行优化。鉴于大型船舶根据计算公式设计外加电流阴极保护方案时在细节方面易存在不足，导致部分区域出现保护不足和过保护，本文分别以保护电位均匀分布和阳极输出电流最小为优化目标，以阳极输出电流为优化参数，将模拟退火算法与边界元方法相结合，编写阴极保护优化设计软件。通过控制冷却进度表，该软件实现了优化过程可控。通过将船舶优化后保护电位分布与优化前对比，分析得出应用本文的优化方法可提高阴极保护电位分布的均匀性和保护方案的经济性，降低析氢反应概率，应用该方法所编写的软件具有较高的优化效率。更多还原

【Abstract】 With the rapid development of China’s shipping industry, ship and ocean structureincreasingly tend to be more and more complicated, which put forward higher request for theeffectiveness of cathodic protection system. Thus seeking practical and effective cathodicprotection potential prediction and optimization method of ship and ocean structures is ofgreat significance to the development of ship and ocean engineering.Traditional cathodic protection design mostly adopts measures or experience to estimatepotential distribution. Actual measurement, while intuitive, high reliability, because of timeand space and environmental factors limit, is often constructed difficulty and expensive.Estimates based on the experience to some extent also cannot guarantee the accuracy of theresults. In recent years the rise of the computer and the numerical simulation technologyprovides a new technical method to the prediction, evaluation and optimization of cathodicprotection system of ship and ocean structures. Numerical simulation method is quick andeconomy, so this article’s research has important theoretical significance and engineeringpractical value.At first, this paper applied traditional formula to design ship and ocean structurepreliminary cathodic protection scheme. According to the structure mode and operatingenvironment and electrochemical properties of the ship and ocean structures, selectedprotection method and main parameter of cathodic protection design——protection potentialand protection current density. Obtained protection area by structure drawings or formula, andthen determined the types and number of auxiliary anode or sacrificial anode. Finallyconclude preliminary scheme which satisfies the requirement of corrosion protection goals.The above work lays the foundation for numerical simulation and optimization of cathodicprotection.This paper used the three-dimensional boundary element method to calculate themathematical model of cathodic protection. Introduced piecewise quasi linearized method todeal with nonlinear problem of boundary conditions. Established linear equations and solve it.Finally applied FORTRAN language to development numerical simulation software forpredicts cathodic protection potential. The software has flexible modeling mode and variousresults output forms, and is advantageous for the operation and practical engineering applications. Compared with experimental data, the results calculated by the software areaccuracy. Applied the software to forecast protection potential of9200TEU container shipimpressed current cathodic protection system and400ft jack-up drilling platform sacrificialanode cathodic protection system, and get accurate results. Put forward the modeling processand the boundary condition setting method according to the engineering applicationexperience. Adopt the method that keep the potential unchange in the polarization curve, andchange current density to simulate coating breakage in simulation process of9200TEUcontainer ship impressed current cathodic protection. Adopt block boundary element methodto solve electrolyte continuous problem and points regional modeling to solve electrolyteinconsistency in400ft jack-up drilling platform sacrificial anode cathodic protection. Themodel loaded into the inside potential value obtained in the calculation of whole area interiorsurface corresponding to the nodes in the model as boundary condition, jack-up platformcomplex node protection potential distribution was obtained. From the results we canconcluded that the400ft jack-up drilling platform sacrificial anode cathodic protection systemmeet the protection targets and the9200TEU container ship impressed current cathodicprotection system needed optimized.With that evenly distributed protection potential and minimum anode output current asoptimize targets, and the anode output current as optimize parameters, combine simulatedannealing algorithm and boundary element method to achive the ship’s cathodic protectiondesign optimization. By controlling the cooling schedule, this software realized theoptimization of process control. Adopt numerical simulation methods to calculate cathodicprotection potential of before and after optimization, and through analysis the potentialcontours of the ship drawn that the methods are feasible and efficient.更多还原