Abstract
The aim of this study was to investigate the action mechanism of the rotor–stator interaction (RSI) on the transient flow field and hydrodynamic noise field inside the impeller of jet centrifugal pumps (JCPs) and optimize effects of the guide vane on the hydraulic and hydroacoustic characteristics of the impeller. The numerical method of CFD (computational fluid dynamics) coupled with CFA (computational fluid acoustics) was used to analyze the correlation between the guide vane and the flow/sound performances of the impeller. The orthogonal test method, with the hydroacoustic performance of the impeller taken as the objective, was used to optimize the structural parameters of the guide vane for the stability of the hydraulic performance of the JCP. The results show that the RSI leads to a significant increase in the hydroacoustic level of the impeller, but it is indispensable for improving the hydraulic performance of the pump. The RSI effect on the fluctuation intensity of the transient flow field inside the impeller is much more sensitive than the time-average, and the fluctuation intensity of the flow field is positively correlated with the vortex intensity inside the impeller. When the impeller geometry is constant, the evolution processes of the flow field inside the impeller are mainly related to the blade number of the guide vane; when the number of guide vanes is given, the RSI effect on the hydroacoustic characteristic of the impeller is characterized by a positive correlation between the total sound pressure level (SPL) and the fluctuation intensity of the flow field. The frequency spectrum characteristics of the hydroacoustic SPL of the impeller are not consistent with the pressure fluctuation characteristics inside the impeller. The pressure fluctuation characteristics are related not only to the blade number and speed of the impeller but also to its wake characteristics determined by the guide vane. The optimization scheme for the stable hydraulic performance of the JCP significantly reduced the total SPL of the impeller compared with the original scheme, which verifies the feasibility of using the weight matrix optimization method to obtain the global optimization scheme.
Highlights
The rotor–stator interaction (RSI) is a ubiquitous phenomenon in turbomachinery [1]
A numerical method that couples Computational Fluid Dynamics (CFD)/Computational Fluid Acoustics (CFA) was used to analyze the correlation between the guide vanes and the hydraulic/hydroacoustic characteristics of an impeller
The RSI leads to a significant increase in the hydroacoustic level of the impeller, but it is indispensable for improving the hydraulic performance of the pump; a good guide vane can improve the transient flow field structure inside the impeller, reduce the flow field distortion phenomena, and improve the hydraulic and hydroacoustic performance of the impeller
Summary
The rotor–stator interaction (RSI) is a ubiquitous phenomenon in turbomachinery [1]. It spreads up- and downstream, resulting in the formation of strong flow field fluctuations in the vaneless area between the dynamic and static cascades, which have an important impact on the stability, safety, and robustness of machines. Zhu et al [9,10] simulated the flow in the centrifugal pump with different volute casings by using a shear stress transport turbulent model, and their findings indicated that the blade passing frequency dominated the pressure fluctuation, radial hydraulic force, and torque in the impeller, whose fluctuations were periodic. They studied the rotor–stator interaction of three tongues of the centrifugal pump using dynamical subgrid-scale models. The flow rate distribution in the guide vanes was relatively uniform, and the amplitude of the pressure pulsation reached the minimum
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