Investigation of cavitation instabilities in a centrifugal pump based on one-element theory

Asian Working Group- IAHR's Symposium on Hydraulic Machinery and Systems

Zhao, G.S.^1,2 ; Zhao, W.G.^1,2

College of Power and Energy Engineering, Lanzhou University of Technology, Lanzhou

730050, China^1

Key Laboratory of Fluid Machinery and System, Gansu Province, Lanzhou

730050, China^2

关键词: Cavitation compliance;    Cavitation inception;    Cavitation instability;    K-Omega turbulence model;    Low specific speed centrifugal pump;    Mass flow gain factor;    Rotating cavitations;    Unsteady cavitating flows;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/163/1/012042/pdf
DOI  :  10.1088/1755-1315/163/1/012042

来源: IOP

【 摘 要 】

In order to investigate the cavitation instabilities in a centrifugal pump, the unsteady cavitating flow in a low-specific speed centrifugal pump was simulated by using a modified SST k-ω turbulence model combined with Kubota cavitation model. The intrinsic and system instabilities of cavitating flow were comprehensively analyzed and interpreted. For the cavity patterns formation process in a centrifugal pump, the separated flow is dominant instead of re-entrant jet flow. The transient incidence angle, cavitation number, cavitation compliance and mass flow gain factor of the middle streamline were addressed in the centrifugal pump at design point based on classical one-element theory in order to characterize the system instability. The results show that the bubbles are static stability at cavitation inception stage, which can reduce pressure fluctuations by varied cavity volume and hard to develop to rotating cavitation. It performs static instability at the stage of development because of the positive-feedback between cavity volume and flow rates, the decreasing of bubble volume would lead to the increasing of flow rate, which can induce undesirable cavitation instabilities.