冲压焊接多级离心泵叶轮的疲劳强度  

Fatigue strength on stamped and welded impeller in multistage centrifugal pump

作　　者：王洋[1] 王维军[1] 王洪玉[1] 叶道星[1] 李贵东[1] 

机构地区：[1]江苏大学流体机械工程技术研究中心,江苏镇江212013

出　　处：《排灌机械工程学报》2013年第3期215-219,229,共6页Journal of Drainage and Irrigation Machinery Engineering

基　　金：国家自然科学基金资助项目(51239005);江苏省自然科学基金资助项目(BK2009218);江苏高校优势学科建设工程项目

摘　　要：为了研究叶轮在运行过程中流场压力脉动作用下的疲劳特性,根据流动及结构的相似性,借助Ansys Workbench多物理场协同仿真平台中的CFX软件,对LVS 3-9型立式多级泵首级内的流场进行数值求解,计算了首级叶轮和导叶中的非定常压力脉动特性.采用流固耦合技术(FSI)中的弱耦合方法将计算得到的叶轮表面流场压力施加到叶轮结构上,分析了叶轮在流场中的受力情况,结合叶轮表面的压力分布特征利用叶轮材料的S-N最小二乘拟合曲线确定了冲压焊接叶轮的疲劳极限,并采用Goodman疲劳极限线图对叶轮结构进行了疲劳强度校核评估.研究结果表明:随着半径的增大,叶轮应力沿叶轮流道从进口到出口逐渐减小,叶轮的变形不断增大,在叶轮边缘达到最大值;在相同半径上,盖板与叶片接合的焊接区域应力明显较大;叶轮的变形均表现为沿轴向的弯曲变形,变形方向指向叶轮进口;电阻凸焊叶轮焊点在各工况下均满足疲劳强度要求,其中叶轮在小流量工况下的应力和应力幅最大.In order to study the fatigue characteristics of an impeller under the pressure fluctuation in a flow field during its operation, the flow field in the first stage of the LVS 3 - 9 vertical multistage pump was simulated by software CFX on the multi-physics platform-Ansys Workbench according to the simi- larity of flow and structure among various stages, then the characteristics of pressure fluctuation in the impeller and diffuser have been obtained. The fluid static pressure obtained by CFD was applied on the structural model of impeller, and the stress and deformation of the structure were analyzed under such a load based on the one-way coupling method for fluid-structure interaction （FSI） in Ansys. Conside- ring the feature of pressure on bladed the fatigue limit of the welded impeller was estimated by best fit- ting the S -N curve of the impeller material obtained based on the least square method. Eventually, the fatigue strength of the impeller structure was assessed by means of the modified Goodman fatigue limit diagram. The results show that the stress in the impeller structure decreases steadily from the inlet to the outlet, the deformation, however, increases gradually and a peak one can be found at the impel- ler outlet. At the same radial position, the obvious stress concentration is located at the welding zones between the shroud and blades. The impeller structure exhibits a bending deformation, which is to- wards to the impeller eye, all in the axial direction. The fatigue strength of the impeller with two wel-ding spots is lower lhan the fatigue limit at all the flow rates and the mean stress and stress fluctuating amplitude are the highest at the low flow rate.

关 键 词：离心泵 叶轮 冲压焊接 流固耦合 疲劳特性 

分 类 号：S227.9[农业科学—农业机械化工程] TH311[农业科学—农业工程]