二维垂直轴水轮机强迫振荡水动力性能分析

Hydrodynamic performance analysis of a 2D vertical current turbine with forced oscillation

潮流能水轮机水动力主要和叶片的相对运动速度有关,为了探讨实际海况条件下,漂浮式立轴水轮机水动力特性与波浪及水轮机的波浪运动响应之间的关系,采用水轮机旋转运动与强迫振荡运动的组合模拟立轴水轮机的纵荡和横荡运动,并用CFX软件对均匀来流中二维水轮机强迫振荡时的流场和水动力特性进行了分析,阐明了不同振荡圆频率、幅值、速比等参数对水轮机水动力的影响规律。研究表明:与水轮机在均匀来流环境中仅做旋转运动相比,横荡使水轮机产生类似卡门涡街的尾迹,纵荡使尾涡间距发生疏密变化;同时水轮机载荷瞬时值的峰值产生较大波动,峰值包络线的波动频率为水轮机振荡频率,在小振幅情况下,包络线波动幅值和水轮机振荡速度的振幅成线性关系。

The hydrodynamic force of the tidal current turbine is related with the relative velocity of the blades. In order to study the relationship between wave motion response and hydrodynamic performance of the floating verticalaxis tidal turbine in the actual ocean environment,this paper simulates the surge and sway motion of the vertical current turbine by combining the turbine rotation and the axial forced oscillation. Using the CFX software,the flow field and hydrodynamic performance of the 2D turbine with forced oscillation in the uniform flow are studied. The influence rule of the parameters at different oscillations,including frequency,amplitude,tip-ratio,etc. on the hydrodynamic performance of the turbine is expounded. The research results showed that,compared with the case that in the uniform flow,the turbine only has rotation motion and the sway motion leads to the wake which is similar to Karman vortex Street. It also showed that the surge motion leads to the change in the interval of wake vortex and at the same time,the peak of the transient load has obvious fluctuation. The fluctuation frequency of the envelope of peaks is equal to the turbine＇s oscillation frequency. When the oscillation amplitude is small the fluctuation amplitude of the envelope has linear relation with the amplitude of the turbine＇s oscillation velocity