Impeller radial force evolution in a large double-suction centrifugal pump during startup at the shut-off condition

Zou, Zhichao; Wang, Fujun; Yao, Zhifeng; Tao, Ran; Li, Huaicheng

doi:10.1016/j.nucengdes.2016.10.034

Cited by 29 publications

(19 citation statements)

References 9 publications

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“…The causes of induced vibration in centrifugal pumps mainly include the mechanical and hydraulic designs. [3][4][5] And so far, the unsteady fluid exciting force cannot be eliminated by effective means, [6][7][8] which is the hotspot and difficulty faced by the current researches. Centrifugal pump unsteady fluid-induced vibration refers to the vibration characteristics shown by a centrifugal pump under complex transient flow impacts such as rotating stall, rotor-stator interaction, inlet and outlet backflows, and cavitation.…”

Section: Introductionmentioning

confidence: 99%

Internal unsteady flow characteristics of centrifugal pump based on entropy generation rate and vibration energy

Jia

Zhu

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part E:

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The transient fluid exciting force induced by unsteady flow in the centrifugal pump is the only exciting force that cannot be effectively eliminated. In order to explore the vibration problem caused by unsteady flow in the centrifugal pump, the steady and unsteady numerical calculations of the internal flow in a centrifugal pump with low specific speed were carried out under different flow rate conditions. With volute circumferential pressure pulsation test, the accuracy of numerical calculations was verified. At the same time, the vibration acceleration sensors were arranged in different positions of the pump body to complete the vibration characteristics experiment under different working conditions. Based on the numerical results, the amount and location of the internal flow loss of the centrifugal pump were predicted by the entropy generation rate method. According to the results of the vibration test, the vibration energy distribution of the centrifugal pump under different working conditions was obtained. In combination with the entropy generation rate and vibration energy distribution, the change rules of flow loss and the vibration energy with the flow condition of the pump were analyzed. By using the frequency-domain analysis method, the pressure pulsation, the unsteady radial fluid exciting force fluctuation and the vibration acceleration were compared and analyzed to study the change rules of the pressure pulsation, the unsteady fluid exciting force and the vibration characteristics with the flow rate. The results show that the internal flow loss is mainly concentrated in the impeller runner near the volute tongue under low flow condition and the internal flow loss under large flow rate condition is mainly concentrated in the volute channel near the pump outlet. The vibration induced by the unsteady flow in the centrifugal pump is mainly low-frequency vibration, which is very sensitive to the change of the flow rate. The vibration energy in the middle- and high-frequency ranges is almost not affected by the working condition. The internal flow loss and the low-frequency vibration energy change with the flow condition, showing similar change rules.

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Section: Introductionmentioning

confidence: 99%

Internal unsteady flow characteristics of centrifugal pump based on entropy generation rate and vibration energy

Jia

Zhu

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part E:

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“…The other approach is to simulate the transient process by taking the boundary condition of the inlet flow rate or the rotational speed of the impeller as a function of time. Zou et al [20] . evaluated the variation of radial force during the starting period of a double-suction centrifugal pump by using this method and summarized the function, describing the variation of radial force with time during the starting period.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Transient Characteristics of a Double Suction Centrifugal Pump System during Starting Period

Jin

Yao

et al. 2019

Energies

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The starting phase for pumps in water transportation pipelines is crucial and has significant transient characteristics which merit further study in order to evaluate the operational stability of the pumping system. This paper presents the results of a study in which the relative steady operating conditions and starting period of a large double-suction centrifugal pump were monitored in real time, including pressure fluctuations, shaft run-out and vibration at the bearing. The transient characteristics of a double-suction centrifugal pump under different operating conditions have been analyzed using fast Fourier transform (FFT) and continuous wavelet transform (CWT). Results indicate broadband frequency components within the spectrum of pressure fluctuations in the volute casing under all test conditions, and the central frequency of the broadband frequency gradually decreases as flow rate increases and approaches the blade frequency, which is the primary reason for an increase in blade-frequency amplitude. This may produce a vibration frequency that is similar to the natural frequency of a certain part of the double-suction centrifugal pump during the starting period, which causes the resonance phenomenon. The radial force is also large during the starting period, which causes eccentric wear of the seal ring at the impeller inlet.

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“…They are widely used in the main feed water systems to ensure the cooling of steam generators as well as the continuous functioning of nuclear power plants. 1 They also have a better cavitation performance as compared to the ordinary centrifugal pumps. The axially split multistage centrifugal pumps with double entry impellers deliver much higher heads at larger flow rates than the conventional double suction pumps due to effects of the multistage and their symmetrical structure.…”

Section: Introductionmentioning

confidence: 99%

Flow loss analysis of a two-stage axially split centrifugal pump with double inlet under different channel designs

Osman

Yuan

Zhao

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part C:

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The double-stage axially split centrifugal pump is widely used in water diversion and water pumping stations due to their ability to deliver at high heads and large flow rate for long running hours. Their flow characteristics can be greatly influenced by the geometry of the channels between the stages, which is a prominent place for irreversible loss to occur. Numerical investigations were extensively carried out and a comparison was drawn between two multistage axially split centrifugal pumps, with different channel designs between its stages. The reliability of the numerical model was confirmed after a good agreement existed between numerical results and the experiments. Subsequently, entropy generation terms were used to evaluate turbulence dissipation to characterize the flow losses. The modified channels had a great effect on reducing swirl near the impeller eye, thereby improving pump head by 12.5% and efficiency by 4.98% at the design condition. They however induced flow impact, causing an unusual separation, which generated high turbulence dissipation at the blade surfaces. The channels and second stage impeller were identified as major areas for selective optimization since their turbulence dissipation was dominant. Consequently, entropy production analysis with computational fluid dynamics could be relied upon to reveal the loss locations for selective optimization in centrifugal pumps.

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Impeller radial force evolution in a large double-suction centrifugal pump during startup at the shut-off condition

Cited by 29 publications

References 9 publications

Internal unsteady flow characteristics of centrifugal pump based on entropy generation rate and vibration energy

Internal unsteady flow characteristics of centrifugal pump based on entropy generation rate and vibration energy

Experimental Investigation of Transient Characteristics of a Double Suction Centrifugal Pump System during Starting Period

Flow loss analysis of a two-stage axially split centrifugal pump with double inlet under different channel designs

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