摘要
为了精确分析离心泵叶轮内复杂的非稳态流动特性,基于泵内流动的大涡模拟(large eddy simulation,LES)数值计算结果,在设计工况及小流量工况下对叶轮内非定常相对速度场进行动态模态分解(dynamic modal decomposition,DMD),得到能够反映叶轮内复杂流动特征的前4阶主要模态及其相应的频率信息。分析结果表明:DMD方法能够有效识别叶轮内复杂流动的脉动频率,提取出相应的流场结构,将叶轮内复杂的流场特征分解为基本模态特征、反映叶轮流道内流动分离及不稳定涡结构的高阶动态模态特征;基本模态能够反映由流道几何形状引起的叶轮出口高速射流区与低速尾迹区及叶片背面流动分离区域。设计工况速度场2阶~4阶动态模态流场反映出叶轮内流动受蜗壳干扰在叶片背面产生的流动分离及不稳定涡结构脱落特征;小流量工况速度场动态模态表征了由于叶轮旋转及蜗壳干扰在流道内发生流动分离、失速等流场特征。通过DMD方法能够有效地对叶轮内重要流场结构进行低维近似,清楚地分析离心泵叶轮内复杂流场的非定常特性。
In order to accurately analyze the complex unsteady flow characteristics in a centrifugal pump impeller,the large eddy simulation(LES)of unsteady flow in the pump was carried out to obtain the flow field distribution within the impeller.Dynamic modal decomposition(DMD)was performed on the transient relative velocity field of the impeller under the designed flow rate condition and small flow rate condition,and the first four modes and corresponding frequency information that can reflect the complex flow characteristics were obtained.The analysis results show that the DMD method can effectively identify the pulsation frequencies of complex flow in impeller and extract the corresponding flow field structures.The complex flow field characteristics in the impeller can be decomposed into basic mode and high order dynamic modes reflecting the flow separation and unsteady vortex structure within the impeller channel.The basic mode can reflect the steady-state flow field characteristics in all the following three regions of the flow passage,caused by the geometrical configuration of the flow passage,namely,the high-speed jet region,low-speed wake region at the impeller outlet and flow separation region on the blade suction side.The second to fourth dynamic modes of the relative velocity field under the designed flow rate condition reflect the flow field characteristics of the flow separation and unsteady vortex structure shedding on the blade suction side caused by the interference of the volute.The dynamic modes of the relative velocity field under small flow rate condition represent the flow field characteristics such as flow separation and stalling in the channel due to impeller rotation and volute interference.The DMD method can effectively approximate the important flow field structures in the impeller,and clearly analyze the complex transient flow characteristics in centrifugal pump impellers.
作者
陈学炳
张人会
蒋利杰
郭广强
CHEN Xuebing;ZHANG Renhui;JIANG Lijie;GUO Guangqiang(School of Energy and Power Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Key Laboratory of Fluid Machinery and Systems,Gansu Province,Lanzhou University of Technology,Lanzhou 730050,China)
出处
《振动与冲击》
EI
CSCD
北大核心
2022年第14期33-40,57,共9页
Journal of Vibration and Shock
基金
甘肃省高等学校产业支撑计划项目(2021CYZC-14)
国家自然科学基金(51979135)。
