考虑旋转效应的离心式叶轮水力阻尼特性研究

Hydrodynamic damping is a phenomenon of mechanical energy dissipation when a dynamic system operates in a fluid environment. Specific to a pump, it is the process that the relative motion of the impeller and the fluid produces energy dissipation, and the amplitude of the vibration attenuates continuously. As one of the key parameters of the fluid induced vibration and fatigue life prediction, the hydrodynamic damping characteristics are still lack of scientific description and in-depth investigation. The research target is to establish a hydrodynamic damping prediction method of a centrifugal impeller with the consideration of rotation effect. In view of the influence of rotation effect on hydraulic damping of a centrifugal impeller, the experimental method is mainly used to break through the relationship between the single mode synergistic excitation and the responses of rotating impeller structure in fluid environment. The hydrodynamic damping characteristics under the low order mode of the impeller structure in the rotating condition to be investigated, in combination with the earlier experimental results of the hydrofoil. Based on the methods of theoretical analysis and numerical calculation, the problems of numerical damping equivalent by adjusting the initial damping and calculation time step are emphatically to be broken through, and the rotation effect correction are to be realized for both structure and fluid domain with Coriolis force. Finally, taking a large centrifugal pump as the analysis object, the hydrodynamic damping characteristic calculation of impeller structure with full channel flow field excitation is to be realized, and the influence of the operating conditions on the hydrodynamic damping characteristics of the impeller is to be analyzed. The investigation results to provide a scientific support for the structural design of the large centrifugal pump impeller in industry.

水力阻尼是动态系统由于水介质的原因引起机械能耗散的现象。具体到水泵中，是叶轮与流体相对运动产生能量耗散，振动幅度不断地衰减的过程。水力阻尼是决定水泵振动幅值和疲劳寿命预测精度的关键参数，至今仍缺乏对其规律的科学描述与深入研究。本项目的研究目标是建立一种考虑旋转效应的离心式叶轮水力阻尼预测方法。为实现这一目标，必须针对离心式叶轮旋转效应对水力阻尼影响问题，以实验研究为主要手段，重点突破旋转叶轮结构单一模态协同激励与响应关系的问题，结合水翼实验结果，研究旋转条件下叶轮结构低阶模态下的水力阻尼特性。采用理论分析和数值计算相结合的方法，重点突破初始阻尼、时间步长与数值阻尼的等效关系难题，实现科氏力对流场和结构场双重影响的旋转修正。最后，以大型离心泵为分析对象，实现基于全流道流场激励下的叶轮结构水力阻尼特性计算，分析多种典型流动状态对水泵水力阻尼特性的影响，为大型离心泵叶轮结构设计提供科学依据。

叶轮与流体相对运动产生能量耗散产生水力阻尼效应。水力阻尼是决定水泵振动幅值和疲劳寿命预测精度的关键参数。本项目针对离心式叶轮旋转效应对水力阻尼影响问题，以实验研究为主要手段，重点突破旋转叶轮结构单一模态协同激励与响应关系的问题，结合水翼实验结果，提出了一种旋转叶轮结构的水下瞬态动力学响应测试方法，并基于该测试方法和数值模拟，揭示了旋转条件下水介质环境中离心式叶轮结构的水力阻尼特性，获得旋转叶轮结构的水力阻尼参数实验值。研究旋转条件下叶轮结构低阶模态下的水力阻尼特性。采用理论分析和数值计算相结合的方法，重点突破初始阻尼、时间步长与数值阻尼的等效关系难题，实现科氏力对流场和结构场双重影响的旋转修正。构建了一种考虑旋转效应的水力阻尼数值预测方法，建立了关键计算参数的定量化确定方法，解决了离心式叶轮的水力阻尼参数精准预测问题。最后，以大型离心泵为分析对象，实现基于全流道流场激励下的叶轮结构水力阻尼特性计算，分析多种典型流动状态对水泵水力阻尼特性的影响，揭示了典型工况下大型离心泵叶轮的水力阻尼特性，构建了工况参数与水力阻尼参数的关系，为大型离心泵叶轮结构设计提供科学依据。项目研究目标已全部实现，已发表学术论文28篇，其中SCI/EI收录25篇；获得授权发明专利5项，获得软件著作权4项；获2021年农业农村部神农优秀创新团队奖（排名第3）。