绕水翼空化流动及振动特性的实验研究  

EXPERIMENTAL INVESTIGATION OF THE VIBRATION CHARACTERISTICS OF HYDROFOIL IN CAVITATING FLOW

作　　者：高远[1] 黄彪[1] 吴钦[1] 王国玉[1] 

机构地区：[1]北京理工大学机械与车辆学院,北京100081

出　　处：《力学学报》2015年第6期1009-1016,共8页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(51306020);北京市自然科学基金(3144034)资助项目~~

摘　　要：空化是发生在水力机械内部的一种水动力现象,其发展具有显著的非定常特性.空化流动中空穴的脱落以及溃灭会诱发结构振动,对水力机械的效率、噪声、安全性等造成影响.研究空化流动中结构的振动特性具有重要的工程意义.采用实验的方法研究了绕NACA66水翼空化流动的空穴形态和水翼振动特性.实验在一闭式空化水洞中进行.采用高速摄像技术观测不同空化阶段的空穴形态,应用多普勒激光测振仪测量水翼的振动速度,并通过一套同步系统实现了高速相机和多普勒激光测振仪的同步触发和测量.采用小波分析方法对不同空化阶段下的空穴形态和水翼振动数据在时域和频域中的特性进行了分析.对云状空化阶段的同步测量结果进行了研究,分析了振动与空穴发展过程的联系.结果表明,随着空化数的降低,流场经历了无空化、初生空化、片状空化和云状空化4个阶段,水翼的振动强度呈逐渐增大趋势.在片状空化和云状空化阶段,空穴脱落导致水翼振动,诱发的振动频率与空穴脱落频率相同.对于云状空化,在附着型空穴生长阶段水翼发生高频小幅度振动,在空穴脉动和断裂脱落期间水翼表现为低频大幅振动.Cavitation is a kind of complex and unsteady hydrodynamics phenomenon occurred in hydraulic machinery.The cavity shedding leads to structure vibration which affects the efficiency, noise and safety of hydraulic machinery, so it is important to study the structure vibration in cavitating flow. The characteristics of the cavity shape around a NACA66 hydrofoil and the vibration response are analyzed experimentally. A high-speed video camera is used to visualize the unsteady cavitating flow patterns and a laser doppler vibration meter is used to measure the vibration velocity. The highspeed video camera and the laser doppler vibration meter can be triggered synchronously by a synchronization system.The characteristics of cavity shape and vibration in different cavitation stages are analyzed both in time field and frequency field. Synchronous results of cloud cavitation are studied. It is found that as the cavitation number decreases, four stages of cavitation are visualized in which are non-cavitation, cavitation inception, sheet cavitation and cloud cavitation. The vibration amplitude of the hydrofoil increases as the cavitation number decreases. Cavities shedding leads to vibrations whose dominant frequencies are same with the frequencies of cavities shedding at sheet cavitation and cloud cavitation stages. At the cloud cavitation stage, the vibration is high-frequency and low-amplitude when the attached cavity develops.At the stages of cavity pulsation and cavity shedding, the vibration is low-frequency and high-amplitude.

关 键 词：水翼 振动特性 空化 实验研究 

分 类 号：O35[理学—流体力学]