The objective of this paper is to investigate the physical interaction of the cavitation-vortex dynamics around a 3D Delft hydrofoil by large eddy simulations combined with the Zwart–Gerber–Belamri cavitation model. Transient sheet/cloud cavitating flows around the twisted hydrofoil involves the primary and secondary cavity shedding characterized by a U-shape structure, which is consistent with previous experimental data. Different vortex identification methods, namely, the ω criterion, Q criterion, Ω method and Liutex method, are applied to identify and analyze the vortex structure. The Liutex method is further utilized to visualize the detail of vortex structure in the primary and secondary cavity shedding process, especially for formation and development of the U- shape structure. For the primary cavity shedding process, the U- shape structure is the main feature of the shedding process. The primary U- shape vortex structure experiences distortion, and breaks into two parts at the vortex neck. Then, the front part develops into a O-shape structure, whereas the rear part still maintains a U- shape structure. Finally, both parts are dissipative completely in the form of U-shape structures. The shear plays a major role in the primary cavity shedding. For the secondary cavity shedding, U-shape, Ω-shape, O-shape, and hairpin vortexes are observed. The secondary U-shape vortex structure twists and deforms to form a hairpin vortex when the secondary cavity sheds completely, and finally dissipates with a smaller magnitude hairpin vortex. Rotation plays a major role in the secondary cavity shedding.

本文的目的是通过结合Zwart-Gerber-Belamri空化模型研究大型涡模拟来研究3D Delft水翼周围空化涡旋动力学的物理相互作用。扭曲水翼周围的瞬态片/云空化流涉及以U形结构为特征的一次和二次腔脱落，这与先前的实验数据一致。不同的涡旋识别方法，即ω准则Q运用Ω法和Liutex法则对涡旋结构进行识别和分析。Liutex方法进一步用于在一次和二次腔脱落过程中可视化涡旋结构的细节，尤其是用于U形结构的形成和发展。对于主腔脱落过程，U形结构是脱落过程的主要特征。主要的U形涡旋结构会发生变形，并在涡旋颈处分成两部分。然后，前部发展为O形结构，而后部仍保持U形结构。最后，这两个部分完全呈U形结构耗散。剪在初级腔脱落中起主要作用。对于次级腔脱落，U形，Ω形，O形，并观察到发夹涡。当次级腔完全脱落时，次级U形涡旋结构扭曲并变形以形成发夹涡，最终消散成较小幅度的发夹涡。旋转在次生腔脱落中起主要作用。