透平机械离心压缩机和离心泵叶轮动力分析的三维旋转循环对称C_N群算法

Application of C_N Group Cyclic Symmetry Method to Three-Dimensional Dynamic Analysis of Centrifugal Compressor and Pump Impeller

以离心压缩机叶轮为例,建立三维有限元模型,采用循环对称CN群算法计算了它的动力特性,详细讨论离心力作用下叶轮的应力状态,分析与轴连接的不同方式对叶轮应力的影响。应用循环对称算法能大大减少建模与计算的工作量,有很好的实用价值。计算结果表明,离心压缩机叶轮在旋转中,叶轮外缘应力比较高,轮盖上的应力较轮盘上的应力大,叶片根部容易产生应力集中,应采用适当的园角避免应力集中,过盈配合的叶轮内孔处应力比较大,需要确定合理的过盈量,既要保证叶轮不松动也要保证叶轮内孔处的强度条件。

For a centrifugal compressor impeller, three-dimensional finite element model is established to evaluate the dynamic characters with CN group cyclic symmetry method, then to obtain stress distribution. Furthermore, the effects of various techniques connecting shaft with impeller of the stress distribution are analyzed. Cyclic symmetry method enables to obviously reduce workload of modeling and calculating to outperform the competing methods in analysis of turbine wheel impeller. It is concluded that in a rotating impeller, its outer part is under a higher stress state and the stress of cover is higher than plate; stress concentration may arise at the blade root. To avoid stress concentration, the blade root ought to be filleted properly. If the impeller is connected with a surplus shaft, the stress near the hole is much higher, so the appropriate surplus is necessary to consider.