基于动边界LES的离心泵非稳定流固耦合及振动特性研究

Obvious inner flow instability exists when centrifugal pump is operating under off-design conditions, resulting in, therefore, unstable fluid-structure interaction (FSI) phenomenon. The FSI effects can cause strong flow-induced vibration of pump and is a key scientific issue that can influence the safe and stable operation of pump unit. Due to the interdisciplinary complexity, the understanding of unstable FSI mechanism under off-design condition is still blank. This project will investigate the unstable FSI effects and induced vibration behaviors of centrifugal pump based on moving boundary LES method. Flow instability in centrifugal pump will be precisely simulated under off-design conditions using LES, and flow patterns as well as pressure fluctuation behaviors will be studied when the frequency characters of unstable flow excitation can be obtained. The prediction model of strong coupling effects between unstable flow and structure will be established based on moving boundary LES, and bottleneck problems of the calculation, such as accuracy, stability, convergence and efficiency problems, will be solved. Then, the experimental research of flow-induced vibration will be carried out by establishing a measurement system based on eddy current vibration sensors, and the FSI simulation results based on LES level can be verified. The FSI laws and vibration behaviors of centrifugal pump will be revealed by using time-frequency analysis based on wavelet transform method, and the relations between main geometrical parameters of hydraulic components and FSI effects will be studied. The project is expected to put forward preliminary control method of FSI vibration of centrifugal pump under off-design conditions, which has important theoretical value and certain actual engineering significance to improve the pump operating stability.

离心泵在非设计工况运行时，内部流动呈现明显的不稳定性，非稳定的流固耦合作用将导致泵的强烈振动，是影响泵机组安全稳定运行的关键科学问题。由于流固耦合多学科交叉的复杂性，对离心泵偏工况不稳定流动作用下流固耦合机制的认识尚属空白。本项目将基于动边界LES方法对离心泵非稳定流固耦合及振动特性开展研究。采用LES方法对离心泵偏工况不稳定流场进行精确数值模拟，揭示流态及压力脉动特性，掌握不稳定流动激励频率特性；建立动边界LES非稳定流固强耦合预测模型，解决耦合计算的精度、稳定性、收敛性及计算效率等瓶颈问题；采用电涡量振动测量系统开展水力振动试验研究，实现对LES层面流固耦合计算的验证；采用基于小波变换的时频域联合分析，揭示非稳定流固耦合规律及振动特性；研究水力部件主要几何参数与流固耦合作用间的关系，初步提出离心泵偏工况非稳定流固耦合振动控制方法。本项目对提高离心泵运行稳定性具有重要的学术和工程价值。

非稳定的流固耦合作用易导致泵的强烈振动，影响泵机组安全稳定运行。本项目对离心泵偏工况运行区域全流道内部复杂流动进行了精确的DES（LES/RANS混合湍流模型）数值模拟，采用统计法和快速傅立叶变换方法全面地分析了由动静干涉引起的压力脉动特性，获得了压力脉动强度分布特性和压力脉动频域特性，掌握了不稳定流动激励频率特性。建立了动边界法的非稳定流固强耦合预测方法，研究了离心泵极端工况下的流固耦合作用，获得了离心泵在启动过程的高温高压动力学特性，同时也建立了在有无空化条件下的离心泵流固强耦合高精度、高可靠性数值预测方法，获得了泵内非定常流固耦合作用下内流与结构的关联特性。搭建了离心泵外特性、压力脉动和振动测量的开式试验台，应用动态压力传感器、加速度传感器采集离心泵不稳定流动状态及空化发展过程中泵进出口处压力脉动信号和蜗壳壁面上的不同测点振动信号，揭示了离心泵不稳定流动作用下的非定常流固耦合机理。对比分析了水力部件不同结构设计参数与结构变形之间的关系，为有效地控制离心泵偏工况非稳定流固耦合振动提供了解决方法。本项目的研究对离心泵非稳定流动的流固耦合数值模拟和实验研究，准确获得泵内部压力脉动和流体结构的流固耦合特性，具有重要的理论与学术价值，同时在工程应用领域具有借鉴意义。.发表项目号标注论文23篇，其中SCI论文检索13篇，EI论文检索7篇。出版学术专著2本。申请发明专利19项，其中发明专利授权14项，发明专利受理5项。申请软件著作权1件。获省部级科技进步二等奖4项，三等奖2项，获镇江市政府论文专著特等奖，获亚洲流体机械青年科学家奖。举办国际学术会议3次，参会人数超过1000人。受邀国际学术会议大会报告2次，国内学术会议大会报告1次。参加国际学术会议12人次。培养博士研究生7名，毕业4名，在读3名，培养硕士研究生12名，毕业8名，在读4名。超额完成项目指标。