This paper investigates the hydrodynamic characteristic of a single-stage centrifugal pump with inlet inducer and outlet Radial Guided Vanes (RGVs) influenced by the clocking effect for the first time. Different from general ones, the outlet RGVs in this paper have specificities. The hydraulic performance and dynamic characteristics of the centrifugal pump are numerically studied and validated by experiments. The results indicate that there is an optimum position of RGVs that can not only increase the pump head and efficiency but also reduce the pressure fluctuation intensity. A non-dimensional parameter describing the velocity non-uniformity of the impeller outlet is first proposed, which is negatively related to the pump’s hydraulic performance. The clocking position of the RGVs will affect the velocity homogeneity at the impeller outlet, and further influence the hydraulic characteristics of the pump. Besides, the clocking effect of outlet RGVs mainly affects the amplitudes of BPF for both the pressure fluctuation and radial force, and the most obvious frequency of pressure pulsation and radial force is 3 BPF correlating with the inlet inducer. It is recommended to install the volute-tongue tip near the middle of two vanes.

In this paper, the wake and potential flow effects of the rotor–stator interaction in a centrifugal pump with guide vanes are investigated from the view of the separation of turbulent and acoustic pressure fluctuations. The highest vibration levels in pumps are, in general, originated in the potential flow and wake effects. However, it is challenging to distinguish their effects on flow evolution. The pellicular mode decomposition method is applied to innovatively separate potential flow and wake disturbances in a centrifugal pump. By pellicular, we mean an infinitely thin layer of air located on the monitoring surface. The pellicular modes are a set of acoustic modes, with which a set of normalized orthogonal basis can be constructed. The impacts of potential flow and wake disturbances are visualized and evaluated quantitatively. The results show that only a very limited region is where the potential flow disturbance works. The higher the harmonics, the smaller the disturbance range. The wake disturbance is responsible for the modal pressure field. Modal pressure fields with low diametrical nodes decay more slowly than those with low harmonics. In addition, special attention is paid to the impact of the geometric asymmetry of the volute on the impeller force. The circular volute with a two-stage pressure drop improves the radial force of the impeller. More deep understandings on the mechanism of the rotor–stator interaction are reached by decoupling the potential flow and wake disturbances. This work serves as a guide for further research in fault diagnosis and vibration control of centrifugal pumps.

In this paper, the aerodynamic noise of a centrifugal fan with an eccentric impeller is investigated and analyzed by adopting a hybrid method combining detached-eddy simulation and the acoustic finite element method (FEM). The impeller-eccentric effect of high-speed centrifugal fans, frequently ignored in theoretical studies, is objective in practical engineering applications owing to machining and installation errors, which have a significant influence on flow characteristics and subsequently noise characteristics. An impeller-whirling model combined with the sliding mesh method is introduced to obtain the actual flow with an eccentric impeller. First, the internal flow field handled with different eccentricities is investigated. The total pressure and internal efficiency decline, and the flow field near the leading edge shows intense unsteadiness, inducing a rise in the pressure fluctuation amplitude at the rotating frequency (RF) in both impeller flow passage and volute domain. Second, the variational formulation of Lighthill’s analogy is implemented by acoustic FEM to better account for the interaction between the solid surface and aerodynamic sound, capturing a contribution by turbulence noise at the second RF. Under eccentric conditions, the sound source intensity shows a circumferential non-uniform distribution in a similar region to the flow field. The calculated sound pressure level captures the variation in the experimental result, which shows an obvious rise at RF induced by the impeller-eccentric effect. The characteristics of the noise spectrum and sound directivity change significantly, and the overall sound pressure level rises with the increase in eccentricity. This study provides an effective simulation strategy for predicting the aerodynamic noise of centrifugal fans under realistic conditions.