一种分析四级离心泵转子系统模态的计算方法

A Method for Modal Analysis of Rotor System of Four-stage Centrifugal Pump

为了提高集中质量解析法求解叶轮质量平衡和偏心时悬臂式四级离心泵转子系统模态的精度,分别采用简化的集中质量数学模型和ANSYS对质量平衡的转子系统固有频率进行求解,通过分析2种计算方法结果的差异,提出了融合轴系质量和模态刚度修正系数的优化数学模型。采用新模型对平衡和有偏心时转子系统的固有频率进行了求解,并将有偏心时的计算结果与ANSYS仿真结果进行比较。结果表明:集中质量解析法得到的固有频率略小;前四阶固有频率的误差由优化前1.28%、2.03%、8.64%和11.82%分别下降至优化后0.77%、1.02%、3.41%和4.52%,刚度的简化是造成误差偏大的主要因素;偏心时各阶固有频率略增大,偏心的叶轮位置越靠近吸入室侧,对固有频率的影响越大;新模型求解偏心时比平衡时所得固有频率的误差大。

To improve the analytical method for solving the modal accuracy of the four-stage centrifugal pump rotor system under the condition of impeller with mass balance and mass eccentricity,a simplified lumped mass mathematical model and ANSYS were used respectively to solve the natural frequency of the rotor system of impeller with mass balance.By analyzing the differences between the two results,an optimized mathematical model combining the shafting mass and the correction coefficient of modal stiffness was presented.The new model was used to solve the natural frequencies of the rotor system under normal and eccentric conditions,and the calculation results under eccentricity were compared with the ANSYS simulation results.Results show that the natural frequency obtained by the analytical method is slightly smaller;the error of the first four-order natural frequency is reduced respectively from 1.28%,2.03%,8.64%,11.82%before optimization to 0.77%,1.02%,3.41%,4.52%after optimization,and the simplification of stiffness is the main factor that causes the error to be large;the natural frequencies of each order increase slightly when the mass is eccentric,and the closer the impeller of mass eccentricity to the suction chamber side,the greater the influence on the natural frequency;the error of solving the natural frequency of the impeller with mass eccentricity is greater than that of mass balance eccentricity in the optimized model.