当弹性管倾斜置于流场中，其尾部流场形态与垂直来流相比有明显差异，此时流固耦合作用更为复杂。采用三维数值模拟方法，对均匀流冲击下的倾斜弹性管的涡激振动开展了仿真研究。首先，通过与试验数据的对比验证了数值方法的可靠性。然后，基于对均方根振幅包络图的显性模态分析，发现随着弹性管倾角的增加，其顺流向涡激振动的最大响应幅值会逐渐下降，横流向最大响应幅值大幅增加。接着，通过位置-频率-能量（PFE）图解技术，可观察到倾斜弹性管在顺流向和横流向上均表现出典型的多模态特性。当弹性管倾角达到30°时，主振模态、振动位移等均有所改变，独立性准则（IP）失效。最后，对尾流场的分析发现，在小角度倾斜条件下尾流区出现平行交叉泄涡，大角度倾斜条件下尾涡为倾斜泄涡模式。

英文摘要:

When slender flexible pipes are installed at an inclination in a flow field, the resulting wake flow differs significantly from that behind a vertically aligned pipe, and the fluid-structure interaction becomes more complex. This study investigates the vortex-induced vibrations (VIV) of an inclined flexible pipe under uniform flow using three-dimensional numerical simulations. Firstly, the reliability of the numerical method is verified through comparing with experimental results. Secondly, based on the dominant mode analysis of the root-mean-square amplitude envelope, it is found that the maximum in-line VIV amplitude gradually decreases, while the maximum cross-flow amplitude increases significantly as the inclination angle rises. Thirdly, analysis using the position-frequency-energy (PFE) diagram reveals that the inclined pipe exhibits typical multi-mode responses in both in-line and cross-flow directions. When the pipe's inclination reaches 30°, the dominant vibration modes and displacements change, and the independence principle (IP) becomes invalid. Finally, wake field analysis shows that a parallel-cross vortex shedding pattern occurs at small inclination angles, while an inclined vortex shedding mode develops at larger angles.

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