利用有限元理论,基于Ansys Workbench工作平台,针对某小型水平轴风力发电机组,计算了不同工况时叶片应变特性的变化。计算结果显示:叶片在气动力作用下最大应变位置位于叶根与叶片径向的0.65 R处、叶片在离心力作用下最大应变位置位于叶根处;在恒定来流风速、低尖速比时,气动力引起的叶片应变大于离心力引起的应变,但随着尖速比的增加,离心力引起的应变值大于气动力作用时的应变值,其原因为离心力正比于尖速比和风速乘积的二次方,而气动载荷仅正比于风速的二次方;气动力与离心力耦合作用时,最大应变位置位于叶根处,离心力与气动力耦合作用时引起的应变不等于离心力与气动力单独作用引起应变之和。研究结果可为风力机叶片机械强度设计提供一定的理论支撑。
Based on Ansys Workbench platform,a simulation was carried out to study the strain change of small horizontal axis wind turbine blade at different conditions using the finite element theory. The solution shown that the position of maximum strain was located at the blade root and at blade radial of 0.65 R caused by aerodynamic force,and the maximum strain was located at the blade root caused by centrifugal force. At a constant wind speed, the strain caused by the aerodynamic force was bigger than that caused by centrifugal force at low tip speed ratio, but with increasing of the tip speed ratio, effect of the centrifugal force was far greater than aerodynamic force. The reason of it was that aerodynamic force was directly proportional to the square of the wind speed u, but the centrifugal force was directly proportional to the square of product between the wind speed u and wind turbine tip speed ratio λ. The maximum strain was also located at the blade root under coupling of the aerodynamic force and the centrifugal force, and the strain value caused by coupling of the aerodynamic force and the centrifugal force was not equal to sum of the strains caused by the centrifugal force and aerodynamic force respectively. The related research results could provide a certain theoretical support for the design of mechanical strength of the wind turbine blades.