The objective of this paper is to study sheet/cloud cavitation dynamics in fluid-structure interaction by experimental and numerical methods. The high-speed camera is applied to observe the cavitating flow structures and the Laser Doppler Vibrometer is used to characterize the vibration. A hydrodynamic load cell is applied to measure the lift and drag static force. The results present different cavitating patterns of the flexible hydrofoil and the vibration amplitude is enhanced when the cloud cavitation occurs. The hybrid coupled fluid structure algorithm is adopted to simulate the cloud cavity shedding downstream due to the re-entrant jet from the cavity closure to the hydrofoil's leading edge. The vibration analysis shows that the frequency spectrum of the flexible hydrofoil is much more complicated than the rigid one, the main cavitating flow-induced vibration frequency of the flexible hydrofoil is due to the cavity shedding, others are corresponding to vortex shedding frequency and natural frequency in water. The Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) methods are used to investigate the dominant coherent structures of the cavitating flow. With the POD method, it reveals that large-scale cloud cavities occupy a large amount of energy in the flow field. The DMD method accurately extracts the dominant frequency and modal characteristic, with the first mode corresponding to the mean flow field, the second mode being cavity shedding and the third and fourth mode being vortex shedding.

本文的目的是通过实验和数值方法研究流固耦合中的片/云空化动力学。高速相机用于观察空化流结构，激光多普勒测振仪用于表征振动。应用流体动力称重传感器来测量升力和阻力静力。结果表明柔性水翼具有不同的空化模式，当云空化发生时，振动幅度得到增强。采用混合耦合流固算法来模拟由于从空腔闭合到水翼前缘的折返射流导致的云空腔向下游脱落。振动分析表明，柔性水翼的频谱比刚性水翼复杂得多，柔性水翼的空化流致振动频率主要是由于空腔脱落，其他对应于涡旋脱落频率和水中的固有频率。适当正交分解 (POD) 和动态模式分解 (DMD) 方法用于研究空化流的主要相干结构。POD方法揭示了大规模的云腔在流场中占据了大量的能量。DMD方法准确地提取了主频率和模态特征，第一模态对应于平均流场，第二模态为腔体脱落，第三和第四模态为涡旋脱落。其他对应于水中的涡旋脱落频率和固有频率。适当正交分解 (POD) 和动态模式分解 (DMD) 方法用于研究空化流的主要相干结构。POD方法揭示了大规模的云腔在流场中占据了大量的能量。DMD方法准确地提取了主频率和模态特征，第一模态对应于平均流场，第二模态为腔体脱落，第三和第四模态为涡旋脱落。其他对应于水中的涡旋脱落频率和固有频率。适当正交分解 (POD) 和动态模式分解 (DMD) 方法用于研究空化流的主要相干结构。POD方法揭示了大规模的云腔在流场中占据了大量的能量。DMD方法准确地提取了主频率和模态特征，第一模态对应于平均流场，第二模态为腔体脱落，第三和第四模态为涡旋脱落。它揭示了大规模的云腔在流场中占据了大量的能量。DMD方法准确地提取了主频率和模态特征，第一模态对应于平均流场，第二模态为腔体脱落，第三和第四模态为涡旋脱落。它揭示了大规模的云腔在流场中占据了大量的能量。DMD方法准确地提取了主频率和模态特征，第一模态对应于平均流场，第二模态为腔体脱落，第三和第四模态为涡旋脱落。