The scale effect of vortex generators, as microstructures, influences cavitation erosion remains unclear, posing a key challenge to applying vortex generators in large-scale hydraulic machinery. In this study, the vortex generators (VGs) with heights of 0.25 mm (micro-VG) and 2.5 mm (large-VG), installed at the leading edge of a smooth NACA0015 hydrofoil, were investigated through experimental and simulation methods. The results demonstrate that the vortex generators can induce tubular vortexes that enhance near-wall flow stability. After installing the VGs, the large-scale cloud cavitation is effectively controlled. On the hydrofoil with micro-VGs, this control manifests as localized, small-scale cavitation shedding and collapse, while on the hydrofoil with large-VGs, the cavitation shedding is entirely absent, which shows that larger VGs further mitigate cavitation effects. Pressure signal analysis reveals that the VGs alter the pressure fluctuation period and reduce the main frequency amplitude compared to that on the smooth hydrofoil, with larger VGs providing superior suppression of pressure fluctuations. Additionally, an improved strength function method is proposed and applied, highlighting that the reduction in large-scale cloud cavitation by the VGs contributes to decreased erosion risk on the hydrofoil, with larger VGs showing enhanced effectiveness in preventing cavitation erosion.

中文翻译：

---

不同尺度上微观结构影响的空化侵蚀特性


作为微观结构，涡流发生器对空化侵蚀的尺度效应仍不清楚，这对涡流发生器在大型液压机械中的应用构成了关键挑战。在本研究中，通过实验和模拟方法研究了安装在光滑NACA0015水翼前缘的高度为 0.25 mm （micro-VG） 和 2.5 mm （large-VG） 的涡旋发生器 （VG）。结果表明，涡流发生器可以诱导管状涡流，从而增强近壁流的稳定性。安装 VG 后，大规模的云空化得到了有效控制。在具有微型 VG 的水翼上，这种控制表现为局部的、小规模的空化脱落和塌陷，而在具有大型 VG 的水翼上，空化脱落完全不存在，这表明较大的 VG 进一步减轻了空化效应。压力信号分析表明，与光滑水翼相比，VG 改变了压力波动周期并降低了主频率幅度，较大的 VG 提供了对压力波动的出色抑制。此外，提出并应用了一种改进的强度函数方法，强调 VG 减少大尺度云空化有助于降低水翼的侵蚀风险，较大的 VG 在防止空化侵蚀方面表现出更强的有效性。