基于附加水动力振动反演的深海平台半隐耦合方法及试验研究

In the study of external marine dynamic environment forces on deep water structures, nonlinear fluid-solid interaction analysis is a key step for motion prediction and stability judgment. When implementing the nonlinear fluid-solid interaction analysis for floating structures used for the exploitation of the South China Sea, added hydrodynamic parameters performed scattered and computed costly. Therefore, we focus on how to improve the dynamic prediction of floating structures one sides, i.e., an estimation method of added mass of fluids based on dynamic response of cylinders in water is proposed, the added damping of surrounded water is also studied based on our damping identification method proposed recently, and the assessment method of slow drift and mooring damping is investigated too. On the other hand, we concentrate on how to reduce the complexity of the complex floating structure with mooring systems to improve the computing effiency, and then a super-model is developed based on model conversion techniques, including interface conditions updating method caused by removing mooring lines, and the measurements dealing with spatial incompleteness of measured mode shapes from limited numbers of sensors and so on. At last, a semi-implicit coupling method is developed by combining the added mass and damping from our above achievements into the control equations of the floating structures. Comparing with the weak coupling algorithms, the approach performs better stability and convergence; and the computing efficiency is improved too comparing with strong coupling algorithms.

在外部海洋动力环境对深海工程结构作用的研究中，非线性流固耦合分析是确定深海平台系统运动响应并判定其稳定性的关键所在。本项目以我国南海油气资源开发为工程背景，针对深海浮式平台非线性流固耦合计算所需附加水动力参数离散性较大并且对计算资源要求较高、计算速度过慢的问题，一方面开展柱体结构上流体附加质量振动反演算法研究，并借助取得的海洋平台非传统阻尼特性识别技术，开展流体附加阻尼振动反演算法，以及浮式平台系统低频运动中慢漂阻尼和系泊系统阻尼的评估方法研究，以提高浮式结构运动响应计算精度；另一方面，研究浮式平台因系泊索截断而引起的边界动力修正方法，探索浮式平台模型转换技术并发展一种超模型以提高计算效率。将流体附加水动力参数融入结构控制方程，发展一种深海浮式平台半隐式耦合算法。该方法介于弱耦合与强耦合算法之间，较弱耦合算法具有更好的稳定性及计算精度，较强耦合算法计算时效更为明显，具有更好的工程应用前景。

项目负责人及其课题组，按照项目资助计划书中约定的研究内容逐项开展，整个项目按照预定计划有序进行，研究内容未进行调整或变动。本项目的主要内容及进展包括以下四个方面：1）基于振动响应的结构附加水动力参数计算方法，实现了基于实测数据的结构附加质量估算；2）非经典结构动力响应频域方法，阻尼矩阵的形式不再局限于比例阻尼；3）考虑非零初始条件的结构频域动力响应方法，提高了传统频域方法无法考虑瞬态响应的不足；4）基于极值留数的 Laplace 域动力响应分析方法，拓展了传统Laplace域动力响应的适用范围。在本项目的资助下，在国内外期刊上发表科研论文 25 篇，其中被 SCI 收录论文 17 篇；参加国内外学术会议 7 次；申请国家发明专利 6 项，其中已授权 3项，授权软件著作权 5 项；培养研究生 8 人。