Numerical and experimental analysis of biomimetic tubercle for cavitation suppression in viscous oil flow around hydrofoil

This study explores the cavitation suppression mechanisms of biomimetic hydrofoils inspired by whale flipper tubercles, focusing on viscous oil flow around hydrofoils. A novel test system for viscous oil cavitation was developed, featuring a high-speed camera to capture transient cavitation phenomena. The study compared the cavitation behaviour of the flow around a basic blade (Base-blade) with that around a biomimetic blade (Bio-blade) designed with leading-edge tubercles. The visualization results demonstrated that the biomimetic structure significantly reduced the degree and unsteadiness of cavitation. The study also employed a three-dimensional CFD model using the Stress-Blended Eddy Simulation (SBES) method and the Zwart-Gerber-Belamri (ZGB) cavitation mass transfer model to reveal the flow mechanism. The Bio-blade reduced the vapour volume fraction by 9.67%, decreased the drag coefficient (<i>C_d</i>) by 9.36%, and minimized the lift fluctuations compared to the Base-blade. The biomimetic design reduces the transient shedding cavitation scale, effectively suppressing severe cavitation events. The Bio-blade inhibited the formation of leading-edge separation vortices and reduced the scale of U-shaped vortices that enhance cavitation evolution. In summary, this study provides a comprehensive analysis of the cavitation suppression mechanisms of biomimetic hydrofoils in high-viscosity fluids, offering valuable insights for future research and engineering applications.

本研究以鲸鳍结节为仿生原型，针对仿生水翼的空化抑制机理展开探究，重点关注水翼周围的粘性油液绕流流动。研发了一套新型粘性油液空化测试系统，搭载高速相机以捕捉瞬态空化现象。本研究对比了基础叶片（Base-blade）与带有前缘结节的仿生叶片（Bio-blade）的绕流空化行为特性。可视化结果显示，仿生结构可显著降低空化的发展程度与非定常特性。本研究同时采用了基于应力混合涡模拟（Stress-Blended Eddy Simulation, SBES）方法与兹瓦特-格贝尔-贝拉姆里（Zwart-Gerber-Belamri, ZGB）空化传质模型的三维计算流体动力学（Computational Fluid Dynamics, CFD）模型，以揭示绕流流动机理。相较于基础叶片，仿生叶片的蒸汽体积分数降低了9.67%，阻力系数（C_d）降低了9.36%，且升力波动得到有效抑制。该仿生设计可缩小瞬态脱落空化的尺度，有效抑制剧烈空化事件的发生。仿生叶片可抑制前缘分离涡的形成，并削弱促进空化演化的U型涡的尺度。综上，本研究全面分析了高粘性流体中仿生水翼的空化抑制机理，为后续相关研究与工程应用提供了极具参考价值的理论依据。