多级离心泵内流激励转子全自由度耦合模型及其动力学特性研究

The coupled dynamic characteristics and vibration mechanism of rotors are the key problems in the rotor dynamics research of multi-stage centrifugal pumps. This project focuses on the coupled vibration characteristics of the holonomic full degrees of freedom rotor system of the multi-stage pump including the multi-scale inner flow excitations by means of simulation, programming and experiment. The flow control equation of fluid element and the motion model of equivalent dynamic coefficients representing the interstitial fluid-induced excitation force under multiple disturbance scales will be established based on the flow patterns and boundary conditions of the real gap structures. The whole basin two-way coupled model of the single impeller will be established from the macro fluid-induced excitation force. The nonlinear functions of three-dimensional whirl and excited forces under multiple conditions will be fitted, and the relationship between the complex whirl of the eccentric impeller and the transient excitation will be explored. The final holonomic full degrees of freedom fluid-solid coupled time-varying motion model of the multi-stage pump rotors will be established based on the finite element method and matrix operation. The spatial-temporal evolution and inherent coupling mechanism of multidirectional coupled nonlinear vibration of high-dimensional rotor systems will be revealed. The project research will deepen the knowledge of the multi-scale coupled vibration phenomenon of the multi-stage centrifugal pump rotors. The coupled dynamic model and research method of multi-stage centrifugal pump rotors will be enriched, and the theoretical support will be provided for the design and research of multi-stage centrifugal pumps with low vibration and high stability.

转子耦合动力学特性及其耦合振动机制是多级离心泵转子动力学研究的关键问题。本项目采用数值模拟、理论编程和实验验证相结合的方法，考虑多尺度内流激励作用，研究完整多级离心泵全自由度转子系统的耦合振动特性。基于真实间隙结构流动形态及边界条件，构建流体微元的流动控制方程，建立多重扰动尺度下表征间隙流体激振力的等效动特性系数运动模型。从宏观流体激励力入手，建立单级叶轮全流域双向耦合模型，拟合多工况下三维涡动-激振力非线性函数方程，探索叶轮偏心复合涡动与瞬态激振的关联关系。最终基于有限元法和矩阵运算方法构建完整多级离心泵转子全自由度流-固耦合时变运动模型，揭示高维转子系统多向耦合非线性振动时空演变规律及内在耦合机理。项目研究将加深对多级离心泵转子多尺度耦合振动物理现象的认识，丰富多级离心泵转子耦合动力学模型和研究方法，为低振动、高稳定性的多级离心泵设计与研究提供理论支撑。

转子耦合动力学特性及耦合振动机理已成为多级离心泵转子动力学研究的关键问题。本项目针对不同尺度的内流激励作用，分别创建相应的流体激振力模型，并将其与转子运动方程进行整合，构建了完整的多级离心泵转子耦合模型，重点研究了内流激励对转子耦合动力学特性的影响作用。针对多级离心泵内部环形密封结构特征，基于整体流动理论，完善压力边界条件，建立了环形密封流体激振力的等效动特性系数模型。考虑平衡盘轴向间隙的动态变化情况，发展了一种可用于求解平衡盘动态轴向激振力的理论模型。建立了离心泵叶轮三维全流道模型，实现了叶轮的复合涡动形态，将数值计算结果与实验结果进行了对比，发现在偏心率为2%时计算得到的流量和扬程比未考虑偏心计算的结果更加接近实验值，进一步探索了叶轮偏心复合涡动与宏观流体激振力的关联关系，并采用最小二乘法拟合得到了非线性叶轮内流激振力的函数表达式。考虑转子轴系大变形带来的非线性弹性力作用，利用多尺度法求解了简化的离心泵转子系统非线性稳态响应，并采用李雅普诺夫相关稳定性理论研究了其稳定特性。基于有限差分法和小参数法求解了滑动轴承的动特性系数，并结合有限元法和空间欧拉角变换建立了多自由度转子轴系运动模型，在此基础上，应用矩阵运算方法实现了轴承和密封动特性系数与轴系运动方程的整合，最终建立了内流激振作用的多级离心泵转子多自由度耦合系统运动模型，研究发现，环形密封内流激励对于转子耦合系统横向动特性和稳定性具有重要影响，且对称结构的排布方式同非对称情况相比转子振幅更小，但是对于轴向动特性影响有限。项目研究成果为高稳定性及低振动的多级离心泵转子系统设计提供了理论参考。