Space-time frequency spectra analyses of the unsteady cavitating vortical flows inside a mixed-flow pump

OCEAN ENGINEERING

卷:238

Article

Huang, Renfang¹  Qiu, Rundi^1,2  Wang, Yiwei^1,2  Luo, Xianwu³  Zhang, Wei⁴ 

[1] Chinese Acad Sci, Inst Mech, Key Lab Mech Fluid Solid Coupling Syst, Beijing 100190, Peoples R China

[2] Univ Chinese Acad Sci, Sch Future Technol, Beijing 100049, Peoples R China

[3] Tsinghua Univ, Dept Energy & Power Engn, State Key Lab Hydrosci & Engn, Beijing 100084, Peoples R China

[4] Sci & Technol Water Jet Prop Lab, Shanghai 200011, Peoples R China

关键词: Mixed-flow pump;    Pressure fluctuations;    Cavitation;    Wavelet analysis;   

DOI  :  10.1016/j.oceaneng.2021.109758

来源: Elsevier

【 摘 要 】

The objective of this paper is to investigate the space-time frequency spectra for cavitating flows in a mixed-flow pump by using both fast Fourier transform and wavelet transform. Unsteady cavitating flows in a mixed-flow pump are numerically investigated by using the Reynolds-averaged Navier-Stokes method, which is closured with SST k-co turbulence model and Zwart cavitation model. The cavitation performance is fairly predicted when compared with available experimental data. There are two stages for unsteady cavitation evolution during one impeller rotating cycle, including the cavity growth stage and diminution stage. The cavitation in the impeller is characterized by the spatial non-uniform distribution since a high-pressure region presents at the impeller inlet plane. The pressure amplitude decreases when the cavitation becomes severer at a smaller operating velocity. Besides, the dominant frequency in the impeller is the impeller rotating frequency (f(n)), i.e. the cavity evolution frequency. Due to the rotor-stator interaction from the six-blade impeller, there is a dominant long-term frequency of 6f(n), in the intake duct and the diffuser inlet. Furthermore, a broadband low-frequency around 1.5f(n), exhibits near the diffuser exit, and the 1.5f(n), amplitude varies over time corresponding to different corner-vortex dynamics. Therefore, wavelet analysis is a more favorable and practical method to obtain time-dependent frequency information for unsteady cavitating flows.

【 授权许可】

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