潮流能水平轴水轮机振动位移时间序列的自相似性研究

Research on self-similarity characteristics of horizontal axis tidal turbine vibration displacement time series

为了研究潮流能水平轴水轮机振动位移时间序列的自相似性,文章在不同的波流共同作用下对20kW潮流能水平轴水轮机进行数值模拟和波浪水槽试验,并将数值模拟与试验结果利用分形维数的方法计算得到Hurst指数,再由Hurst指数判断上述位移时间序列是否具有自相似性。数值模拟和试验结果表明:潮流能水轮机振动位移时间序列具有自相似特征,为采用自相似理论研究潮流能水轮机的动态特性奠定了数学基础,所揭示的时间序列整体与局部之间的关系及其自相似性为潮流能水轮机的故障诊断提供了技术支撑。

In order to test the hypothesis of self-similarity characteristic of the horizontal axis tidal turbine vibration displacement time series, the performances of a 20 kW tidal turbine under different conditions of wave and current interactions was studied. Simulation and flume experiments were carried out on the turbine and Hurst indexes were calculated respectively on the results of simulation and experiments by using method of the fractal dimension, which indicates how self-similar the tidal turbine vibration displacements were in time domain. The result of the simulation and experiments all showed that the tidal turbine vibration displacement time series could be characterized as self-similar,which means that dynamic characteristics of tidal turbines could be studied by using self-similarity theory and this self-similarity characteristic between partial and the whole time series could be used as a basis for fault diagnosis and fatigue analysis of tidal turbines.