EI、Scopus 收录
中文核心期刊

绕弹性水翼云状空化多级脱落特性研究

STUDY ON MULTI-STAGE SHEDDING CHARACTERISTICS OF CLOUD CAVITATION AROUND FLEXIBLE HYDROFOILS

  • 摘要: 采用实验和数值模拟相结合的方法, 对绕弹性水翼云状空化开展了研究, 主要分析了云状空化多级脱落现象及其导致的水翼振动特性. 实验方面, 利用高速相机观测了空泡形态演化过程. 数值模拟方面, 结合标准PANS (partially-averaged Navier-Stokes)湍流模型和Zwart空化模型对流场进行数值模拟, 并运用紧耦合算法实现了流固耦合计算. 结果表明: 当空化数处于0.65 ~ 0.85范围内时, 绕弹性水翼云状空化存在多级脱落现象, 其中一次脱落和二次脱落过程存在明显差异. 一次脱落尺度和周期明显大于二次脱落; 一次脱落和二次脱落机制不同, 前者是中部回射流所致, 后者是自由端回射流所致; 一次脱落空泡产生的高压区面积显著大于二次脱落空泡但压力峰值相对较小, 并且一次脱落空泡产生的高压区对附着空泡生长抑制作用更强, 使二次脱落附着空泡生长速度和最大长度相对于一次脱落分别减小47%和40%; 一次脱落附着空泡表面旋转流动强度更大, 一次脱落空泡主要受剪切效应影响, 而二次脱落空泡主要受旋转效应影响; 弹性水翼所受水动力载荷变化主要与一次脱落有关, 二次脱落的影响较弱, 其中一次脱落阶段尖端变形最大值比二次脱落大5%, 同时结构振动各阶主频与空泡脱落频率一致.

     

    Abstract: The study investigates the cloud cavitation around a flexible hydrofoil using a combined approach of experimentation and numerical simulation. It focuses on analyzing the multi-stage shedding phenomenon of cloud cavitation and its induced hydrofoil vibration characteristics. Experimental observations of the evolution of cavity morphology are conducted using high-speed cameras. Numerical simulations of the flow field are performed using the standard PANS (partially-averaged Navier-Stokes) turbulence model and Zwart cavitation model, with a tight coupling algorithm for fluid-structure interaction analysis. Results indicate that within the range of cavitation numbers between 0.65 and 0.85, multi-stage shedding of cloud cavitation occurs around the flexible hydrofoil, with significant differences between primary and secondary shedding processes. Primary shedding exhibits larger scales and periods compared to secondary shedding; the mechanisms behind primary and secondary shedding differ, with the former attributed to mid-chord re-entrant jet and the latter to free-end re-entrant jet. The high-pressure area generated by primary shedding cavity is significantly larger but with relatively smaller pressure peaks compared to secondary shedding, exerting a stronger inhibitory effect on the growth of attached cavity, resulting in slower growth rates and smaller maximum lengths of secondary shedding cavity compared to primary ones. Primary shedding attached cavity surface rotational flow intensity is greater, the primary shedding cavity is mainly affected by shear effects, while the secondary shedding cavity mainly affected by rotational effects. The change of hydrodynamic loads on the elastic hydrofoil is mainly related to the primary shedding, and the effect of secondary shedding is weaker, while the main frequency of each order of structural vibration is consistent with the shedding frequency of cavity.

     

/

返回文章
返回