【作者】 邵卫东；

【导师】 唐友刚；

【作者基本信息】 天津大学 ， 船舶与海洋工程， 2012， 硕士

【摘要】 深海立管是深海油气资源勘探开发的关键设施,所处的服役环境复杂。本文考虑深海立管顶部浮体运动及涡激振动的耦合作用,研究立管的动力响应。本文提出了两种立管模型:两端铰支,轴力定常的理论分析模型和考虑张紧环运动及轴力随水深变化的实际立管结构模型。对这两种立管模型进行固有振动特性分析,确定其振动频率及模态;提出了考虑浮体升沉运动影响的立管参激-涡激耦合振动分析模型,研究参数激励下立管发生参激共振的条件,并分析阻尼对立管参激不稳定区的影响;利用数值计算的方法,分别计算立管单纯涡激振动和参激-涡激耦合振动情况下的动力响应,应用结构的S-N曲线及Miner损伤理论计算立管的疲劳损伤,研究不同海洋环境参数及立管结构参数对于立管动力响应及疲劳损伤的影响。研究表明,考虑张紧环运动及轴力随水深的变化,立管的横向振动频率小于理论模型的振动频率;对于立管系统的参激不稳定性,当平台的升沉频率接近或者等于立管横向振动频率2倍时发生一阶参激共振,这部分参激不稳定区是立管参激振动最重要的部分;考虑立管上部浮体运动导致的参数激励影响,立管的横向振动响应增大、疲劳损伤增大,研究结果表明立管设计时要充分考虑参激振动和涡激振动的耦合响应。更多还原

【Abstract】 The risers are the key facilities in the oil and gas exploration in deep sea, theservice environment is very complicated. The dynamic response is studiedconsidering the coupling between heave motion of the platform andVIV.The two riser models are proposed: one is the theorical analysis model, the axialforce is const and the riser is pinned; the other one is practical model, the axial forceis varying with the water-depth, and the top of the riser is connected to thetension-ring. First, the natural vibration characteristics of deep-water riser are studiedto confirm the frequency and the modal; Secondly, the vibration analysis model isproposed considering the coupling between the parametric excitation caused by theheave motion of platform and VIV to discuss the parameter instability and thedamping’s effect to the instability. Finally, the dynamic responses of VIV and coupledVIV-Parametric excitation are calculated using the numerical evaluation, also thecumulative damage is computed considering the S-N curve and Miner theory.Parameters of the riser and marine environment are changed to study therelationship between dynamic response and these parameters.Research shows that the frequencies are different between the two models, as thepractical model’s results are smaller than the theorical model’s results. For theparameteric instability, when the heave frequency is twice the natural frequency of theriser, the first order parametric instibility occured, this zone is the most important anddangerous zone. When calculating the dynamic response, the parametric excitationmakes the response larger than that without parametric excitation, and the cumulativedamage is much bigger than which has no parametric excitation, the same asparametric excitation’s effect to the cumulative damage. As a result, when design thedeep-water riser, the coupling between parameter excitation and VIV must beconsidered.更多还原