Study of flow instability in off design operation of a multistage centrifugal pump

Shibata, Akiha; Hiramatsu, Hideto; Komaki, Shutaro; Miyagawa, Kazuyoshi; Maeda, Manabu; Kamei, S.; Hazama, R.; Sano, Takeshi; Iino, Masamichi

doi:10.1007/s12206-016-0101-1

Cited by 34 publications

(18 citation statements)

References 5 publications

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“…While numerous studies have investigated the pressure fluctuation and unsteady characteristics in different kinds of pumps, which includes the effects of working conditions [14,16], inlet guide vanes [17], tip clearance [18], and volute curvature [19][20][21], but the influence of the number of diffuser vanes on the pressure fluctuation in the centrifugal pump is unclear and further investigation is needed. So, in this paper a numerical approach was adopted in a centrifugal pump with a different number of diffuser vanes, and the pressure fluctuations are analyzed and compared in detail.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Pressure Fluctuation and Unsteady Flow in a Centrifugal Pump

et al. 2019

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A pump is one of the most important machines in the processes and flow systems. The operation of multistage centrifugal pumps could generate pressure fluctuations and instabilities that may be detrimental to the performance and integrity of the pump. In this paper, a numerical study of the influence of pressure fluctuations and unsteady flow patterns was undertaken in the pump flow channel of three configurations with different diffuser vane numbers. It was found that the amplitude of pressure fluctuation in the diffuser was increased gradually with the increase in number of diffuser vanes. The lower number of diffuser vanes was beneficial to obtain a weaker pressure fluctuation intensity. With the static pressure gradually increasing, the effects of impeller blade passing frequency attenuated gradually, and the effect of diffuser vanes was increased gradually.

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Section: Introductionmentioning

confidence: 99%

Numerical Study of Pressure Fluctuation and Unsteady Flow in a Centrifugal Pump

et al. 2019

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“…Especially, the inner flow instabilities intensify while the pumps operate under these conditions, which deviate a lot from the designed flow rate. Complicated flow instabilities can be easy to discover through visualization experiments and numerical simulations under part load conditions in pumps, which include the rotating stall, the backflow, and the viscous wake [10,11]. The unsteady flow in the pump not only results in the unsteady dynamic characteristics, which include the pressure pulsations and the hydraulic excitation force [12], but also causes the vibration of the structures and the noise [13].…”

Section: Introductionmentioning

confidence: 99%

Detection of the Flow State for a Centrifugal Pump Based on Vibration

Liu

Zeng

et al. 2019

Energies

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A combined numerical and experimental method study was performed to detect the inner flow state for a type of centrifugal pump. It was found that the inlet attack angles of blades in an impeller have a great influence on the flow instabilities in a centrifugal pump. The mechanism of the rotating stall in the impeller channel was explained. Meanwhile, flow state identification with vibration (FSIV) was proposed to detect the flow instabilities in a centrifugal pump. The relationship between the external vibration and the inner flow state has been established by FSIV. The characteristics and mechanism of the vibration produced by the flow instabilities in a centrifugal pump were investigated. It was found that the hump, the rotating stall, the backflow, the occurrence of unstable flow, and the cavitation in the centrifugal pump can be effectively detected by applying the vibration signals, which helps to obtain safe and steady operating conditions for the system.

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“…The periodical separation and detachment made the low-frequency components more complicated, with higher amplitudes. The characteristic frequency was 70% of the rotating frequency, which corresponded with the feature of the rotating stall phenomenon, inside the impeller [49][50][51][52].…”

Section: Discussionmentioning

confidence: 88%

Unsteady Flow Numerical Simulations on Internal Energy Dissipation for a Low-Head Centrifugal Pump at Part-Load Operating Conditions

et al. 2019

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Dredge pumps are usually operated at part-load conditions, in which the low-solidity centrifugal impeller could experience large internal energy dissipation, related to flow separation and vortices. In this study, SST k-ω and SAS-SST turbulence models were used, in steady and unsteady simulations, for a low-head centrifugal pump with a three-bladed impeller. The main focus of the present work was to investigate the internal energy dissipation in rotating an impeller at part-load operating conditions, related to flow separation and stall. The unsteady nature of these operating conditions was investigated. Performance experiments and transient wall pressure measurements were conducted for validation. A methodology for internal energy dissipation analysis has been proposed; and the unsteady pressure fluctuations were analyzed in the rotating impeller. The internal power losses in the volute and the impeller were mostly found in the centrifugal pump. The rotating stall phenomenon occurred with flow separation and detachment at the part-load operating condition, leading to a dissipation of the internal energy in the impeller. The rotating impeller experienced pressure fluctuations with low frequencies, at part-load operating conditions, while in the design operating condition only experienced rotating frequency.The energy loss in the centrifugal pump could be divided into flow dissipation, disk friction, and discharge leakage loss. Kara Omar et al. [7] calculated the losses through empirical and semi-empirical models, and verified them with experimental results. El-Naggar [8] conducted an experimental one-dimensional flow analysis and predicted the pump performance in a dimensionless form. Klas et al. [9] performed simulations on a centrifugal pump and investigated the energy loss in different flow components, to detect the influence of the component geometry. These studies focused on the whole energy transformation in flow components, without a detailed loss analysis.The inner flow characteristic was investigated as the energy loss reasons for centrifugal pumps. Posa et al. [10] investigated the streamline distribution on the impeller blade surface and found that a stall phenomenon developed near the impeller shroud. Zhang et al. [11] applied velocity vector distribution to detect the flow pattern near the volute tongue, and to discuss its effects on the efficiency fluctuation of a centrifugal pump. Barrio et al. [12] detected a counter-rotating vortex near the interface between the impeller and the volute, through velocity distribution. Pacot et al. [13] used the pressure distribution to explore the stall propagation mechanism. Asim et al. [14] applied the Q-criterion to illustrate that a secondary flow generated near the volute tongue, with an impact on the pump head. Miorini et al. [15] and Zhou et al.[16] adopted a vorticity study to investigate tip leakage flow and rotating stall, respectively, to describe the development of these unsteady flow phenomena and to prove their effects on pump performance. These m...

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Study of flow instability in off design operation of a multistage centrifugal pump

Cited by 34 publications

References 5 publications

Numerical Study of Pressure Fluctuation and Unsteady Flow in a Centrifugal Pump

Numerical Study of Pressure Fluctuation and Unsteady Flow in a Centrifugal Pump

Detection of the Flow State for a Centrifugal Pump Based on Vibration

Unsteady Flow Numerical Simulations on Internal Energy Dissipation for a Low-Head Centrifugal Pump at Part-Load Operating Conditions

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