海水对深海服役输油立管的腐蚀作用会不断改变立管表面形态和动力特性,从而显著影响立管涡激振动响应。因此,本文基于X70管线钢模拟深海环境腐蚀试验结果,分析了不同腐蚀率的立管涡激振动响应。首先,对X70管线钢标准挂片进行模拟深海环境腐蚀试验,获得材料腐蚀速率和壁厚损伤程度时变模型;然后,根据相同腐蚀速率下单位面积腐蚀损失质量一定的等效原则,建立表征不同腐蚀率立管的有限元模型;最后,采用嵌套网格技术实现计算域内网格动态更新来考虑立管与流场的流固耦合,分析腐蚀立管的横流向和顺流向涡激振动响应幅值以及锁定区间。研究表明:当腐蚀率较小时,腐蚀对立管涡激振动呈现出较强抑制作用,最大横流向和顺流向振幅分别是光滑立管的53.4%和16.7%,且提前进入并推后离开锁定区间。但是,随着腐蚀率增加,立管涡激振动响应急剧增加,在腐蚀率为4.07%至22.74%内,腐蚀立管涡激振动响应幅值都大于光滑立管,最大横流向和顺流向振幅分别是光滑立管的1.16倍和1.17倍,进入锁定区间与光滑立管基本相同,但推后离开锁定区间。当腐蚀率为28.09%时,腐蚀立管涡激振动响应有所降低,但横流向振幅仍大于光滑立管,进入锁定区间与光滑立管基本相同,但较大幅度提前离开锁定区间。
Abstract
The corrosive effect of seawater on oil risers in deep-sea service gradually alters the riser surface characteristics and dynamic properties, which significantly influences the riser vortex-excited vibration response. Therefore, this study investigates the vibrational response of vortex excitation in risers with varying rates of corrosion, leveraging simulated corrosion tests on X70 steel, a standard material for deep-sea pipelines. Firstly, corrosion tests are conducted on X70 steel samples in a simulated deep-sea environment to establish time-dependent models for corrosion rates and wall thickness degradation. Subsequently, according to the equivalent principle that ensures a constant mass loss per unit area under the same corrosion rate, finite element models for risers with different corrosion rates are established. Finally, the nested mesh technique is employed for dynamic mesh updates within the computational domain to account for fluid-structure coupling between the riser and the flow field to analyze the amplitude of vortex-induced vibrations in the transverse and incoming directions of risers with different corrosion rates as well as the corresponding locking range. The study reveals that when the corrosion rate is low, it exerts a pronounced inhibitory effect on vortex-induced vibrations of the riser. The maximum amplitudes in the transverse and incoming directions are 53.4% and 16.7% of those observed in smooth risers, respectively, and is accompanied by an alteration in the locking range, with advanced entry and delayed exit. Conversely, as the corrosion rate increases to the range of 4.07% to 22.74%, the response to eddy-induced vibrations in the riser increases significantly. For corroded risers, the amplitudes surpass those of smooth risers, reaching 1.16 and 1.17 times in the transverse and incoming directions, respectively. The entry into the locking range remains largely consistent with that of smooth risers, but the exit is delayed. When the corrosion rate reaches 28.09%, the eddy-induced vibration response in the corroded riser decreases but remains amplitude in the transverse greater than that in the smooth riser. The entry into the locking range remains consistent with smooth risers, but the exit from the locking range experiences a more substantial advance.
关键词
结构工程 /
涡激振动 /
腐蚀海洋立管 /
响应幅值 /
锁定区间 /
腐蚀率
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Key words
Structural engineering;Vortex-excited vibration /
Corroded ocean risers /
Response amplitude /
Locking range /
Corrosion rate
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