半潜式平台方形立柱波浪爬升抑制方案与性能研究

As the main equipment used for oil and gas exploitation in the South China Sea, the semi-submersible exposed to extreme sea states may suffer from the incidents of negative air gap and wave impact owing to critical wave run-ups on the surface-piercing square columns. Because of the nonlinearities, randomness and near-field interference, the wave run-up and air gap have been of increasing concerns in the research and practice of offshore engineering. The present project aims to propose an innovative concept of mounting porous barriers on the square column surface for the wave run-up obstruction through comprehensive studies of the concept and its performance. The research content includes the following issues: the mechanism and characteristics of wave run-ups on the surface-piercing square columns; the conceptual design and its performance of mounting porous barriers on the square column surface for wave run-up obstruction; coupling effects between the wave run-up obstruction and the platform motions and near-field wave interference of a semi-submersible with square columns; prediction of air gaps of a semi-submersible in consideration of obstructing wave run-ups. Through the research, the following objectives are expected: propose the conceptual design of mounting porous barriers on the surface-piercing square column of a semi-submersible for obstructing wave run-ups and improving air gap performance; reveal the characteristics and flow mechanism of wave run-up phenomenon with obstruction and the interaction with the motions and near-field wave interference. The research will substantially improve the understanding on the issues of wave run-up and porous obstacle and provide an effective resolution and a scientific basis for improving the safety performance related to the air-gap and wave impact of a semi-submersible exposed to extremely severe environments.

半潜式平台是我国南海开发主力装备，在极端海况下立柱波浪爬升可能造成负气隙和波浪砰击，导致安全事故。波浪爬升与气隙由于显著的非线性、随机性、近场干涉效应，已成为国际海洋工程研究领域前沿热点问题。本项目创新提出在方形立柱上加装孔隙消波结构以抑制波浪爬升，并开展抑制方案和消波性能研究，内容包括：方形立柱壁面波浪爬升机理与特性，方形立柱波浪爬升抑制方案与性能，半潜式平台运动和近场干涉与波浪爬升抑制的耦合效应，考虑立柱波浪爬升抑制方案的半潜式平台气隙性能数值预报。通过研究，提出半潜式平台方形立柱附加孔隙结构方案，可有效抑制立柱波浪爬升和改善平台气隙性能；揭示方形立柱采用抑制方案后波浪爬升过程的时空变化规律和流场机理，以及立柱波浪爬升抑制与平台运动和近场波浪干涉的耦合作用机理。研究成果将丰富波浪爬升与孔隙消波相关机理和规律的理论认知，为半潜式平台极端海况下的气隙安全保障提供新的解决方案和科学依据。

半潜式平台在极端海况下的波浪爬升可能造成负气隙和波浪砰击，导致安全事故。波浪爬升与砰击由于显著的非线性、随机性、近场干涉效应，成为国际前沿热点问题。本项目针对方形立柱半潜式平台，开展立柱壁面波浪爬升机理与特性、波浪爬升抑制方案与性能、半潜式平台波浪爬升与砰击、运动和气隙与波浪爬升抑制耦合效应等研究。取得重要结果如下：（1）首次将多层孔隙结构用于半潜式平台，提出方形立柱附加多层孔隙结构进行消波和抑制波浪爬升的新方法，揭示了孔隙消波过程的演化规律和流场机理，验证了耗散波浪能量和抑制波浪爬升的效果。（2）创新提出用于半潜式平台改善气隙性能的立柱附加多层外飘式波浪爬升抑制结构方案，发现合理设计外飘角后可有效偏折波浪爬升水体，显著降低波浪爬升高度和波浪砰击风险，具有良好抑制效果，并可明显减小半潜式平台纵摇运动响应。（3）发展了基于计算机视觉的瞬时爬升波面测量方法，可准确测量波浪爬升液面演化并捕捉水射流瞬态轮廓；提出小波去噪和频域响应函数方法，可有效进行超高频波浪砰击载荷数据降噪处理和消除动态干扰。（4）揭示了方形立柱波浪爬升及近场干涉机理，陡波波峰与立柱抬升水体的非线性相互作用导致迸发强烈水射流和放大波浪爬升倍数，后立柱波浪爬升受绕射波波峰回流叠加影响较大，受到近场干涉效应影响显著。（5）发现了半潜式平台波浪砰击载荷与波浪爬升速度和高度紧密相关，提出重要砰击事件的六种模式并分别揭示砰击载荷空间分布特征；构建了计及结构物出入水效应的半潜式平台非线性耦合运动模型，发现了非线性共振纵摇运动和共振周期漂移现象。发表标注基金资助的研究论文27篇，其中SCI收录18篇，EI收录26篇。获得授权美国发明专利1项，申请中国发明专利2项。培养博士生4名，硕士生1名。研究成果既丰富了波浪爬升、砰击与消波相关机理和规律的理论认知，也为半潜式平台运动和气隙性能预报、安全气隙设计和降低波浪砰击风险提供了新的解决方案和科学依据。