【作者】 沙勇；

【导师】 王永学；

【作者基本信息】 大连理工大学 ， 港口、海岸和近海工程， 2007， 博士

【摘要】 随着海洋油气资源开发的飞速发展，海底管线的应用日渐增多。为探索海底管线在海洋环境条件下的灾变过程和损伤机理，并为其安全评估提供理论基础和科学依据，本文通过物理模型试验和数值模型计算，对悬跨弹性海底管线动力响应开展相关研究。海底管线动力响应与海底管线失稳、强度破坏、疲劳损伤等密切相关，掌握海底管线动力响应规律是准确进行海底管线安全评估的基础。本文基于水弹性模型比尺，设计了一套近壁悬跨弹性海底管线动力响应试验研究方案，并针对海底管线服役期间常见海洋环境，开展平底固床、冲蚀固床上悬跨海底管线在规则波、不规则波、水流作用下的动力响应物理模型试验研究，给出了平底固床上悬跨海底管线动力响应受悬跨高度、波浪条件、水流条件的影响规律，以及冲蚀固床上悬跨海底管线动力响应受冲坑长度、波浪条件、水流条件的影响规律，可为认识悬跨海底管线灾变过程、损伤机理和评估悬跨海底管线的安全提供科学依据。在数值研究方面，本文利用三维弹性动力学方程，结合莫里森方程，较好地模拟了规则波浪作用下近壁悬跨弹性海底管线动力响应过程，结合不可压缩流体N-S方程和连续方程，进行管线及其内部流体的三维流固耦合数值计算，基于数值计算结果探讨内流管线系统的动力特性和管内流体特征。该数值方法对于进一步研究管内复杂流体对管线系统的动力特性影响、管线振动过程中管内复杂流体的变化具有重要意义。海底管线动力响应对管线安全不利，为有效地减小不利环境荷载条件下海底管线的动力响应幅度，工程中通常是在管线上布置扰流器附件，但目前为止，对扰流器减振的作用机理还不完全清楚。本论文最后部分以海底管线扰流器减振为背景，利用无量纲化的N-S方程和质量-弹簧系统对平行翼板或螺旋翼板剖面开展二维圆柱涡激振动流固耦合数值计算的探索性研究。将任意拉格朗日-欧拉(ALE)和主从(leader-follower)网格控制方法共同应用到圆柱涡激振动研究中，有效地保证了圆柱大位移运动时流体网格的质量。并对低雷诺数下有、无扰流翼板圆柱的涡激振动进行了多组数值计算，对多种翼板圆柱的尾流场涡旋形式、动力响应、升力和阻力系数进行了比较与分析，探讨了扰流翼板对圆柱涡激振动的影响机理，分析结果表明：翼板圆柱响应幅度、升力和阻力系数受翼板布置形式影响很大，且振幅大小明显地依赖于升力系数和圆柱振动的相位差。更多还原

【Abstract】 Submarine pipelines have been more widely used with the rapid development of offshoreoil-gas exploitation. To provide theoretical foundation and scientific basis for disaster process,damage mechanism and safe assessment of submarine pipelines in an offshore environmentalcondition, investigations have been conducted on dynamic response of submarine suspendedelastic pipeline, based on model tests and numerical simulation.Dynamic response of submarine pipeline plays an important role on destabilization,strength fracture and fatigue damage. Understanding the regularity of dynamic response ofsubmarine pipeline is the basis of assessing the safe of submarine pipeline validly. In thispaper, experiments have been conducted on the dynamic response of elastic submarinepipelines suspended over flat or typical erosion beds in waves or currents of common marineenvironment for coastal or offshore submarine pipeline in service, based on the hydroelasticsimilitude criteria. A rather reasonable program and method are established for experiment ofdynamic response of submarine pipeline suspended over sea beds. The strain amplitudes andvibration frequencies are analyzed and discussed on the model pipeline over flat or typicalerosion beds in waves or currents, providing scientific basis for understanding disasterprocess and damage mechanism, and assessing safe of submarine pipelines. In the numericalstudy, three-dimensional elastodynamics equations and Morison equation are applied tosimulate the time histories of dynamic response of submarine pipelines suspended over flatbeds sucessfully. The three-dimensional interaction of pipeline and internal flow isnumerically simulated by applying the iterative computation to the fluid-structure interfacesand using the elastodynamic equation and the incompressible fluid N-S equation andcontinuity equation. Based on the numerical results, the features of pipeline dynamicresponses and internal flows are analyzed and discussed for various internal flow velocities.This method could provide a basis to study the fluid-structure interaction of pipeline andcomplex internal fluid.Dynamic response of submarine pipeline is disadvantageous for pipeline safe. Tosuppress response amplitude of submarine pipeline in an unfavorable marine environment,spoiler attachments are usually applied in practice, however, suppression mechanism ofspoilers is not completely understanded. Based on submarine pipeline spoilers,two-dimensional fluid-structure numerical investigation of cylinders with various sets of fins has been conducted by applying non-dimensional N-S equation and mass-spring systemsimplification. Arbitrary Lagrangian Eulerian (ALE) method and leader-follower method areused together in these numerical simulations, availably keeping good quality of the fluiddomain mesh for large displacements of fluid-structure interface. The vortex inducedvibration for bare cylinder and cylinders with different sets of fins is numerically simulated atlow Reynolds numbers. Vibration response, lift coefficients, drag coefficients and wakevortex mode are compared and analysed for cylinders with different sets of fins. Suppressionmechanism of the fin spoilers on the cylinder response is discussed by comparing the wakecharacteristics of a finned cylinder to those of a bare cylinder. The numerical results indicatethat configuration of fins affects wake vortex mode, response amplitude, lift coefficients anddrag coefficients. Meanwhile response amplitude has a strong relationship with the phasebetween the lift force and the cylinder motion.更多还原