振动水翼低阶振型的阻尼特性试验研究  

Experimental Investigation on Damping Characteristics of a Vibrating Hydrofoil in Low-Order Modes

作　　者：曾永顺 齐鑫 姚志峰[1,2] 王静竹 王一伟 王福军[1,2] CENG Yong-shun;QI Xin;YAO Zhi-feng;WANG Jing-zhu;WANG Yi-wei;WANG Fu-jun(College of Water Resources&Civil Engineering,China Agricultural University,Beijing 100083;Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System,Beijing 100083;Key Laboratory for Mechanics in Fluid Solid Coupling Systems,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190)

机构地区：[1]中国农业大学水利与土木工程学院,北京100083 [2]北京市供水管网系统安全与节能工程技术研究中心,北京100083 [3]中国科学院力学研究所流固耦合系统力学重点实验室,北京100190

出　　处：《机械工程学报》2022年第5期108-118,共11页Journal of Mechanical Engineering

基　　金：国家自然科学基金(51879266,51839001);中央高校基本科研业务费专项资金(2020TC116);中国农业大学研究生自主创新研究基金(2020XYZC03A)资助项目。

摘　　要：水力机械过流部件与环境流体相互作用产生的附加质量和阻尼效应,对其动力响应特性有显著影响。本研究重点测量了空气和水中振动水翼前四阶振型的阻尼特性参数。通过在水翼前缘嵌入一个压电片施加激励,采用激光测振仪和水翼尾缘的压电片同时获取振动响应信号并相互校准,构建了叶片式结构模态参数测试系统。将压电片信号作为基准信号,同步激光测振仪的多点响应信号,提出了一种单振型测量方法。重点分析了对数衰减法、希尔伯特变换法、共振放大法、半功率带宽法和圆圈拟合法五种常用的阻尼比识别方法。结果表明:五种阻尼比识别方法的精度和不确定度在同一量级,综合比较后认为,对于自由振动响应信号推荐采用对数衰减法,强迫振动响应信号则推荐采用半功率带宽法;空气和水中在同一振型条件下,水翼不同位置点的阻尼比基本保持不变,最大偏差为5.8%;相比空气环境,水中水翼各阶固有频率下降率在6.49%~26.73%之间,各阶模态对应的振型未见明显差异;水中振动水翼阻尼比变化趋势依赖于具体振型,其中,1阶弯曲、1阶扭转和1阶弯扭振型对应的阻尼比分别增大13.09%、8.61%和14.34%,但2阶弯曲振型对应的阻尼比则减小16.25%。Added mass and damping effects are induced by the fluid structure interaction(FSI) between submerged structure of hydraulic machines and the environmental fluid, which have significant influences on the vibration characteristics of submerged structures. The damping characteristic parameters of the first four-order modes of a vibrating hydrofoil in air and water are measured,based on experimental tests. By inserting a piezoelectric patch(PZTp) on the leading edge of the hydrofoil to apply excitation, a laser Doppler vibrometer(LDV) and another PZTp(on the trailing edge) are used to simultaneously obtain vibration response signals and calibrate each other, and then a modal parameter testing system is constructed. A single mode shape measurement method is proposed by taking the signal obtained by the PZTp as the reference signal and synchronizing the multi-point response signals obtained by the LDV. Five kinds of commonly used damping ratio identification methods including logarithmic decay method, Hilbert transform method, resonance amplification method, half power bandwidth method and circle fitting method are analyzed. The results show that the accuracies and uncertainties of the five damping ratio identification methods are at the same level. After comprehensive comparisons, the logarithmic decay method is recommended for the free vibration response signal, and the half power bandwidth method is recommended for the forced vibration response signal. At the same vibration mode in air and water, the damping ratios of different measurement positions of the hydrofoil are nearly the same with the maximum deviation of 5.8%. The natural frequency reduction rates of hydrofoil in water range from 6.49%-26.73% as compare to air condition, and no difference in the mode shapes of test modes is observed. The damping characteristics of the vibrating hydrofoil in water are depended on the specific modes.Specifically, the damping ratios of the first bending, first torsional and first bending-torsion combined modes in water are a

关 键 词：水力机械 水翼 阻尼识别方法 阻尼比 振型 

分 类 号：TV136[水利工程—水力学及河流动力学]