Abstract
Multistage centrifugal pumps can provide high-pressure fluid flow, and is widely used in various engineering applications. However, the pressure fluctuation in the pumps strongly affects the flow and pressure stability. To gain further insight into the pressure fluctuation of multistage centrifugal pumps, a numerical model of a typical multistage centrifugal pump model was constructed and the flow investigated systematically under different operating conditions. Changes in amplitude, frequency, and phase of pressure fluctuation in the impellers, diffusers, and pump cavities were observed and analyzed in both time-domain and frequency-domain. The pressure fluctuations of the fluid in the impeller were found to originate from the inlet side of the outward diffuser, whereas that in the diffuser arose from the outlet side of the impeller blade. In contrast, the pressure fluctuations in the pump cavity were initiated from the outlet side of the impeller blade and the interstage leakage of fluid. This study also conclude that the pressure fluctuations are essentially a wave with identifiable amplitude, frequency, and phase.
Highlights
Multistage centrifugal pumps are widely used in various engineering sectors, such as oil, mining, power, and irrigation.1–5 Any increase in the number of pump stages renders the instability of the multistage centrifugal pump system vital
The pressure fluctuation caused by the rotor-stator interaction (RSI) between the rotational impeller and the stationary diffuser may lead to strong vibration and noise in the multistage centrifugal pump during its operation
Shi et al.27 simulated the pressure fluctuation at the downstream of the impeller outlet in a diffuser pump using computational fluid dynamics (CFD); they found that RSI between the impeller and the diffuser is due to the impact of the wake flow on the diffuser
Summary
Multistage centrifugal pumps are widely used in various engineering sectors, such as oil, mining, power, and irrigation. Any increase in the number of pump stages renders the instability of the multistage centrifugal pump system vital. The pressure fluctuation caused by the rotor-stator interaction (RSI) between the rotational impeller and the stationary diffuser may lead to strong vibration and noise in the multistage centrifugal pump during its operation. Shi et al. simulated the pressure fluctuation at the downstream of the impeller outlet in a diffuser pump using CFD; they found that RSI between the impeller and the diffuser is due to the impact of the wake flow on the diffuser. Liu et al. studied the pressure fluctuation of radial diffusers in a multistage centrifugal pump, and showed that the impeller blade passing frequency has the strongest influence and the amplitude of pressure fluctuation is reduced gradually with an increase in the number of pump stages. While most of the studies focused on the main flow parts of the pumps (such as the impellers, diffusers, and pump cavities), the volumetric leakage and interstage leakage have not been investigated. The phase of the pressure fluctuation wave in a multistage pump is to be investigated
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