非定常流动环境下大功率多级流程离心泵动力学特性研究

The purpose of the project is to carry out systematic and in-depth study on dynamic characteristics of high-power multistage process centrifugal pump under unsteady flow condition from theoretical analysis, numerical simulation and experiment. There are three key scientific problems to solve: the first is to accomplish the precise numerical simulation on the interior whole flow field of the pump; the second is the distribution laws of fluid force induced by unsteady flow under the whole flow field; the last one is the establishment of the dynamic model on the rotor system based on the fluid exiting force.. The project is to construct the dynamic subgrid stress model for large eddy simulation based on the Reynolds stress constraints and Lagrange track average. And then numerical simulation of the entire unsteady flow field in multistage centrifugal pump is carried out in the whole flow range. The internal correlation between unsteady flow and fluid exiting force is analyzed. The distribution law of fluid exciting force under the whole flow field is revealed. A function of fluid exciting force is established. The dynamic model on the rotor system is established under the action of fluid exciting force. It is to present the analysis and calculation method of dynamic characteristics and dynamic behavior of rotor system. And the influence law of fluid exiting force on the vibration of the centrifugal pump is analyzed. The suppression methods in fluid-induced vibration problem are presented. The project would lay theoretical foundation and technological support for research method and industrial application of high performance high-power multistage process centrifugal pump.

本项目拟采用理论分析、数值模拟和实验的方法针对非定常流动环境下大功率多级流程离心泵动力学特性开展深入研究，涉及三个关键科学问题：一是流程离心泵内全流场非定常精确数值计算，二是全流场作用下流体激振力的分布规律，三是流体激振力作用下转子系统动力学模型的建立。. 本项目首先构建基于雷诺应力约束和拉格朗日轨迹平均的动态亚格子应力模式，用大涡模拟法获得离心泵全流量工况、高精度的流场信息；分析非定常流动和流体激振力的关联，揭示全流场作用下流体激振力的分布规律，建立流体激振力的表征函数；构建流体激振力作用下转子系统动力学模型，提出大功率多级流程离心泵轴系的动力学特性与动力学行为的分析计算方法；分析流体激振力对振动的影响规律，提出流体激振的抑制措施。通过研究将形成较为完善的大功率多级流程离心泵动力特性研究方法，为高性能泵的设计制造及其应用提供理论支撑。

多级离心泵广泛应用于石油化工和电力工业等行业，是国民经济必不可少的重要流体输送设备。但泵内非定常流体激励造成的振动是影响多级离心泵安全稳定运行的重要因素。目前还未很好掌握大功率多级流程离心泵内部流动特性和转子动力特性，流程离心泵内全流场非定常精确数值模拟计算、流体激励力作用下转子系统动力学模型等关键科学问题未能有效解决。. 本项目围绕非定常流动环境下大功率多级流程离心泵动力学特性，通过理论分析、数值计算和实验方法开展研究，基于螺旋度和拉格朗日轨迹追踪方法对非线性亚格子模型进行构建，确立了适合多级离心泵内瞬态旋转湍流的计算方法，实现了内部流动的精确模拟和性能预测。通过对比不同流量下泵内压力、速度、熵产、涡分布等特征，发现泵内叶片尾缘脱落涡与隔舌等的动静干涉是引起泵内压力脉动的重要因素，为多级离心泵流体激振抑制提供重要的参考和依据。建立了以主流场激振力为主要激振源、间隙流场激振力影响等效刚度、附加质量和等效阻尼的多级离心泵转子系统非定常流体激振模型，实现了非定常流体激励下的转子动力学特性的准确预测。基于多级离心泵流体和转子动力学特性分析，提出了切割叶轮尾缘、改变叶片出口形状等流体激振抑制措施，通过改善叶轮叶片出口的流动结构，降低泵内压力脉动强度及叶轮上径向力，降低多级离心泵内非定常流体激励的振动，为多级离心泵减振设计提供了重要的理论依据。. 研究成果完善了多级离心泵的设计理论，现已应用于多台多级及单级离心泵的水力性能和转子动力特性的预测、设计开发，降低了实验成本并缩短了设计开发周期，为离心泵的安全稳定运行提供了保障。