1. School of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou 730050, China;
2. Key Laboratory of Fluid Machinery and Systems, Gansu Province, Lanzhou University of Technology, Lanzhou 730050, China
Abstract：In order to accurately analyze the complex unsteady flow characteristics in 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 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 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 impeller can be divided into basic mode, high order dynamic mode reflecting flow separation and unsteady vortex structure within the impeller channel. The basic mode can reflect the steady-state flow field characteristics caused by flow passage, including the high-speed jet region and 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 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 stall 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 impeller.
Key words: centrifugal pump; unsteady flow; large eddy simulation(LES); flow separation; dynamic modal decomposition(DMD)
陈学炳1，张人会1,2，蒋利杰1，郭广强1. 离心泵叶轮内非定常流动的动态模态分解分析[J]. 振动与冲击, 2022, 41(14): 33-40.
CHEN Xuebing1，ZHANG Renhui1,2，JIANG Lijie1，GUO Guangqiang1. DMD analysis on the unsteady flow in a centrifugal pump impeller. JOURNAL OF VIBRATION AND SHOCK, 2022, 41(14): 33-40.
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