离心泵小流量迟滞效应内流机理及其诱发振动特性研究

Flow instability and induced vibration in centrifugal pump is a key problem involving the operational stability of the whole system. The hysteresis effect is a special expression form in performance curve of the unstable flow in part load operational region, which reflects the nonlinear interaction law in flow transient process. This leads directly to the sharp change of hydraulic performance and the increase of flow induced vibration level. As a result, the stability of the unit operation could significantly reduce. It is necessary, therefore, to carry out in-depth study of the scientific problems involved. Based on the theoretical analysis, numerical simulation and experimental measurement, in this project, the calculation method of the transient flow with the consideration of water weak compressibility will be established, and the experimental measurement and analysis of the transient flow field characteristics will be carried out. The nonlinear transient flow mechanism of the hysteresis effect will be deeply studied. The numerical model of fluid-structure coupling in transient process will be established based on Moving Boundary Method and Large Eddy Simulation to reveal the nonlinear fluid load characteristics and the coupling vibration behaviors in the hysteresis process. The effect of flow control methods on the unstable flow in part load region will be investigated, and the active control technology for flow instability in hysteresis effect will be obtained. A multi-parameter Swarm Intelligent Optimization method for hysteresis effect will be established to realize global optimization for reducing hysteresis effect in centrifugal pump. On this basis, the operating stability of the centrifugal pump in part load region can be improved obviously, which has important academic significance and engineering application value.

离心泵不稳定流动及其诱导振动是涉及机组稳定运行的重大问题。迟滞效应作为小流量区不稳定流动的特殊外特性表现形式，反映了不稳定流动的暂态非线性作用规律，会直接导致水力性能的急剧改变以及水力振动现象的加剧，显著降低机组运行稳定性，因此，非常有必要对其中的科学问题进行深入研究。本项目以理论分析、数值模拟和实验测量为研究方法，拟建立考虑流体弱可压缩性的瞬变流数值计算方法，开展瞬态流场特征的实验测量与分析，获得迟滞效应暂态过渡过程中的非线性瞬变流机理；建立基于动边界法和大涡模拟的暂态过程流固耦合数值计算模型，揭示迟滞效应非线性流体载荷特性及耦合激振规律；研究流动控制方法对小流量不稳定流动的影响规律，获得迟滞效应不稳定流动的主动控制技术，建立外特性曲线迟滞效应的多参数群智能优化方法，实现对离心泵迟滞效应的全局优化。本项目研究将显著提升离心泵小流量区的运行稳定性，具有重要的学术意义和工程应用价值。

离心泵不稳定流动及其诱导振动是涉及机组稳定运行的重大问题。迟滞效应作为小流量区不稳定流动的特殊外特性表现形式，会直接导致水力性能的急剧改变以及水力振动现象的加剧，显著降低机组运行稳定性。本项目搭建了离心泵瞬态特性测量系统，开展了瞬态流场特征的实验测量与分析，实现了外特性和压力脉动特性参数的同步采集，获得了离心泵压力脉动特性；基于CEL语言实现了在CFX求解过程中工况连续变化，构建了迟滞效应流态转换暂态过程中非线性瞬变流数值模拟方法，获得了离心泵内部压力脉动强度分布，揭示了迟滞效应区域泵内部不稳定内流机理；通过小波分析获得了迟滞效应区域压力脉动时频域特性，掌握了迟滞效应临界点附近压力脉动特性、外特性和不稳定内流之间的关系；采用DES方法数值模拟了离心泵内部不稳定流动特性，基于Omega涡识别方法对泵内部非定常涡结构进行了分析，掌握了涡结构的空演化规律。提出了离散遗传算法的改进策略，基于Workbench平台实现了叶片参数化建模、数值模拟和数据分析的自动化运行，建立了基于改进离散遗传算法和近似模型的离心泵压力脉动优化方法，显著降低了离心泵隔舌压力脉动。. 本项目以理论分析、数值模拟和实验测量为研究方法，对离心泵不稳定内流特征、压力脉动特性、迟滞效应区瞬变流及压力脉动特性、瞬态涡结构演化特性及压力脉动优化方法进行了研究，具有重要的理论与学术价值，同时在工程应用领域具有指导意义。. 发表学术论文15篇，其中SCI收录13篇，EI收录2篇；国家发明专利授权4件。出版学术著作1部；培养毕业博士研究生1名和硕士研究生5名。获得包括英国机械工程师学会最佳论文奖（Edwin Walker Prize）和中国精品科技期刊顶尖学术论文（学科被引次数前1%）等学术荣誉。. 项目已圆满完成全部预期目标。