采用扭杆单元分析汽轮机长叶片振动的有限元法

A FINITE ELEMENT METHOD WITH TWISTED BEAM ELEMENTS FOR ANALYSING VIBRATION OF LONG BLADES OF STEAM TURBINE

本文提出了计算电站汽轮机长叶片固有振动的一种数值方法。为了反映长叶片自然扭曲度大的特点和缩减自由度,该方法将长叶片简化为扭杆,并从扭杆位移函数出发推导出扭杆的弹性势能、动能以及离心力势能,进而将长叶片沿高度离散为扭杆单元,并建立扭杆单元的弹性力刚度矩阵、离心力刚度矩阵和质量矩阵。应用实例表明,该方法的频率计算值和实测值相当接近,能满足工程实际要求。

A numerical method is presented for predicting the natural vibration of the long blade of steam turbine of power stations. The long blade is simplifided as a twisted beam to reflect the twist and to reduce the degrees of freedom of the long blade. By introducing the displacement function of the twisted beam the kinetic energy, elastic energy and centrifugal energy functions are formed. Then the long blade is dispersed along its height to elements of the twisted beam. thus the elastic stiffness matrix, centrifugal stiffness matrix and mass matrix are all established. The numerical results and experimental data agree reasonably well.