三叶片垂直轴水轮机结构动力响应分析

提出采用改进离散涡和几何精确梁理论混合方法对三叶片垂直轴水轮机进行结构动力响应分析.相比传统的有限元方法，该方法具有求解速度快、建模简单、计算精确等优点.在模态分析中，计算了不同叶片高度下，水轮机叶片和整体的前五阶固有频率，分析了水轮机半径大小和叶片高度对固有频率的影响，结果显示:随着尺寸的增加，叶片和整体固有频率显著减小，整体固有频率更易受到半径大小的影响.在瞬态分析中，考虑了离心载荷和叶片的水动力载荷，得到在工作状况下，旋转一周过程中叶片的最大变形曲线；分析了在不同H/R（叶片高度和半径的比值）的情况下的叶片强度问题，结果显示:当H/R大于3.0时，叶片强度将会失效.

Investigation on Structural Dynamic Responses of Vertical-Axis Tidal Current Turbines

The 3D numerical analysis on the blade dynamic responses of the vertical-axis tidal turbines was presented based on the discrete vortex method of University of British Columbia (DVM-UBC) and the geometrically exact beam theory (GEBT).For the first time the GEBT was used to perform the dynamic analysis for tidal current turbines.Compared with the traditional 3D finite element method,the proposed method has advantages of saving computing cost,easily building the model,high calculation accuracy and so on.In the modal analysis,the obtained natural frequencies of the single blade and the entire turbine with various height-to-radius (H/R) ratios show that,the arm size has larger influence on the frequency than the blade size.In the transient dynamic analysis,the deflections at blade tips in one rotation cycle with various H/R ratios were calculated.According to the design optimization of the turbine geometry,it is found that when the H/R ratio is greater than 3.0,the maximum blade deflection will go beyond the critical blade deflection,which means strength failure of the turbine blades.