大型立式泵叶轮振动及疲劳特性研究

Study on Vibration and Fatigue Characteristics of a Large-scale Vertical Pump Impeller

大型立式泵叶轮是将机械能转换为流体动能以及势能的核心部件。为了研究某大型立式泵叶轮的振动及疲劳特性,运用ANSYS软件,采用声-固耦合法,计算了叶轮在湿态工况下的固有频率,研究了叶轮可能的激励频率,并将之与湿态固有频率进行对比分析。分析结果表明:叶轮最小湿态固有频率至少高于可能激励频率45%,叶轮无共振风险;计算了叶轮在离心力以及稳态CFD压力载荷共同作用下的静强度,再结合模型泵的压力脉动测试数据以及原型泵的现场运行工况信息,设置了相应的叶轮疲劳载荷谱,并根据德国机械工业委员会(FKM)规范对其进行了多工况疲劳性能校核;最后,根据Miner疲劳损伤累积理论,计算得出叶轮的最大疲劳累积损伤利用度仅为29.5%,叶轮无疲劳破坏风险。

The large-scale vertical pump impeller is the core component to convert the mechanical energy into the fluid kinetic energy and potential energy.In order to study the vibration and fatigue characteristics of a certain large-scale vertical pump impeller,firstly,its natural frequencies under wet condition are calculated by using acoustic-solid coupling method in the ANSYS software,and its possible excitation frequencies are also investigated,both mentioned above are analyzed contrastively.The analysis results show that the minimum natural frequency of the impeller under wet condition is 45%higher than the possible excitation frequencies at least and there is no resonance risk.Then,the static strength of the impeller is calculated under the joint action of centrifugal force and steady-state CFD pressure load.And the corresponding fatigue load spectrum of the impeller is set through combining with model pump pressure pulsation test data and prototype pump field operation condition information,and the fatigue performance verification under multiple working conditions are carried out according to Forschungskuratorium Maschinenbau(FKM)guideline.Finally,the maximum fatigue damage utilization degree of impeller is only 29.5%by calculation according to Miner fatigue damage accumulation theory,and there is no fatigue damage risk for impeller.