基于循环试验水槽开展了小间隙比掺氢柔性悬跨管在内外流耦合作用下的振动响应试验，测试了管床间隙比（悬跨管至底壁的距离与管径的比值）为0.2、外流约化速度为7.82~21.36以及内流掺氢比为0%~50%范围的悬跨管振动响应，通过交叉小波（cross wavelet transform，一种用于信号处理和数据分析的数学工具，通过计算交叉小波系数来反映两个信号在时频分布上的相关程度）与小波相干（wavelet coherence，通过计算小波变换后信号之间的相干度来揭示它们之间的频域联系和时域相关性）分析方法，分析了外流涡激振动与内外流耦合诱导振动的相干性。研究结果表明：充满静水的悬跨管在过渡状态下的临界约化速度为14.50，当掺氢比分别为0％、15％、25％时，流向振动临界约化速度转移至17.75、19.65、21.32，横向振动临界约化速度转移至17.75、20.20、21.32，即模态过渡（系统从一个稳定模态转换到另一个稳定模态的过程，在这一过程中，系统的振动频率、振动形态以及能量分布都会发生变化）发生的临界约化速度随掺氢比的增加而升高；在低约化速度时，振动频率始终小于段塞流动频率，内流对耦合振动的影响占据主导地位，在高约化速度时，掺氢量越少，耦合振动受外流的影响越大。随着掺入氢量的增大，外流涡激振动与内外流耦合诱导振动的强相干性占比逐渐减小，即外流涡激振动对耦合振动的贡献减弱；而随着外流约化速度的增加，两者的相干性增强，即外流涡激振动对内外流耦合诱导振动的贡献增大。

英文摘要:

An experimental study on the coupling vibration response of a subsea suspended spanning pipeline under the interaction of internal and external flows was conducted using a circulating water flume. The gap ratio between the suspended pipeline and the bottom wall (the distance between the pipe and the bottom wall relative to the pipe diameter) was set at 0.2. The internal flow was a hydrogen-blended multiphase flow with hydrogen volume fractions ranging from 0% to 50%. Vibration responses were measured at reduced flow velocities between 7.82 and 21.36. The cross wavelet transform (CWT, cross wavelet transform is a mathematical tool used in signal processing and data analysis for examining the correlation between two signals in their time-frequency distributions by calculating cross wavelet coefficients) and wavelet coherence (WC, wavelet coherence is a method that reveals the frequency-domain relationships and time-domain correlations between the signals by calculating the coherence of their wavelet-transformed counterparts) analysis methods were employed to examine the coherence between vortex-induced vibration (VIV) and coupling vibration. The findings show that the critical reduced velocity of a water-filled suspended pipeline in a transitional state is 14.50. When the hydrogen blending ratios are 0%, 15%, and 25% respectively,the in-line response thresholds shift to 17.75, 19.65 and 21.32, while the cross-flow response thresholds correspondingly transition to 17.75, 20.20 and 21.32 under identical conditions. This indicates that the critical reduced velocity for mode transition (the process by which a system transitions from one stable mode to another, during which its vibration frequency, vibration mode, and energy distribution change) increases with the hydrogen blending ratio. At low reduced velocities, the vibration frequency remains below the slug flow frequency, indicating that the internal flow dominates the coupling vibration. At higher reduced velocities, the effect of the external flow on coupling vibration becomes more significant as the hydrogen blending ratio decreases. As the hydrogen blending ratio increases, the proportion of strong coherence between external vortex-induced vibration (VIV) and internal-external flow coupling vibration gradually diminishes, suggesting a reduced contribution from the external flow to the coupling vibration. Conversely, as the reduced velocity increases, the coherence between the two increases, suggesting a larger contribution from external flow to the coupling vibration.

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