Effect mechanism of cavitation on the hump characteristic of a pump-turbine

Li, Deyou; Song, Yechen; Lin, Sanbao; Wang, Hongjie; Qin, Yonglin; Wei, Xianzhu

doi:10.1016/j.renene.2020.11.095

Cited by 70 publications

(24 citation statements)

References 16 publications

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“…The turbulent flow in the multiphase pump is very complex, three-dimensional, random, and irregular, and changes with time and space, carrying countless vortices with different sizes and shapes depending on the geometric space of the flow field. In order to simulate such a flow accurately and efficiently, the RANS (Reynolds averaged Navier-Stokes) equations combined with k-ω SST (Shear Stress Transport) turbulence models were employed in this research, because of their good stability and applicability and which have been confirmed in a large number of examples in engineering practice and scientific research [34,35]. As the pump is one of rotating machinery, a two-dimensional simulation will reduce the accuracy of the results and lose lot information of the flow field, so a fully three-dimensional simulation is carried out in the present study as most researchers have done.…”

Section: Governing Equations Numerical Methods and Boundary Conditionsmentioning

confidence: 99%

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

et al. 2021

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The turbulence dissipation will cause the increment of energy loss in the multiphase pump and deteriorate the pump performance. In order to research the turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump, the spiral axial flow type multiphase pump is researched numerically in the present study. This research is focused on the turbulence dissipation rate distribution characteristics in the directions of inlet to outlet, hub to rim, and in the circumferential direction of the rotating impeller blades. Numerical simulation based on the RANS (Reynolds averaged Navier–Stokes equations) and the k-ω SST (Shear Stress Transport) turbulence model has been carried out. The numerical method is verified by comparing the numerical results with the experimental data. Results show that the regions of the large turbulence dissipation rate are mainly at the inlet and outlet of the rotating impeller and static impeller, while it is almost zero from the inlet to the middle of outlet in the suction surface and pressure surface of the first-stage rotating impeller blades. The turbulence dissipation rate is increased gradually from the hub to the rim of the inlet section of the first-stage rotating impeller, while it is decreased firstly and then increased on the middle and outlet sections. The turbulence dissipation rate distributes unevenly in the circumferential direction on the outlet section. The maximum value of the turbulence dissipation rate occurs at 0.9 times of the rated flow rate, while the minimum value at 1.5 times of the rated flow rate. Four turning points in the turbulence dissipation rate distribution that are the same as the number of impeller blades occur at 0.5 times the blade height at 0.9 times the rated flow rate condition. The turbulence dissipation rate distribution characteristics in the pressurized unit of the multiphase pump have been studied carefully in this paper, and the research results have an important significance for improving the performance of the multiphase pump theoretically.

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Section: Governing Equations Numerical Methods and Boundary Conditionsmentioning

confidence: 99%

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

et al. 2021

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“…Since the clearance backflow and structure in the full tubular pump increase the complexity of the pump inlet flow field, it is very necessary to select a suitable turbulence model to capture the details of these flow fields. As we all know, the SST k-ω turbulence model has a high predictability in the internal flow and the external energy characteristics, which gives highly accurate predictions of flow separation under adverse pressure gradients [27,28]. In this simulation, the turbulent energy k equation and turbulent eddy frequency ω equation can be written as follows [29]:…”

Section: Boundary Conditions and Turbulence Modelmentioning

confidence: 99%

Comparative Analysis of Strength and Modal Characteristics of a Full Tubular Pump and an Axial Flow Pump Impellers Based on Fluid-Structure Interaction

Shi

Zhu

Wang³

et al. 2021

Energies

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Fluid-structure interaction (FSI) was used to determine the structural mechanical characteristics of full tubular and axial-flow pumps. The results showed that as the flow rate increases, the total deformation and equivalent stress are significantly reduced. The max total deformation (MTD) and the max equivalent stress (MES) of the full tubular pump impeller occur on the outer edge of the blade. There are two stress concentrations in the full tubular pump impeller, one of which is located in the outlet area of the rim, and the other is located in the outlet area of the hub. However, the MES of the axial-flow pump appears in the center of the blade hub. The performance difference between the full tubular pump and the axial-flow pump is mainly caused by the clearance backflow. The natural frequency of the full tubular pump is lower than that of the axial-flow pump on the basis of the modal results. The MES of the full tubular pump is mainly concentrated at the junction of the blade and the motor rotor, and the max thickness of the rim is 6mm, which can be more prone to cracks and seriously affect the safety and stability of the pump.

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“…In order to intuitively reproduce the interna operating point in the S-shaped region, and comprehensively simulation results and the feasibility of calculation resources Naiver-Stokes (RANS) method was adopted in this study turbulence model is a two-equation model based on turbu turbulent dissipation rate, which is suitable for a high Reynolds [25]. The k-ω model takes into account the compressibility of propagation rate of the free shear flow, which is commonly u [26][27][28]. In this study, the SST k-ω model provided by comm selected.…”

Section: Numerical Simulation Strategymentioning

confidence: 99%

“…The common k-ε turbulence model is a two-equation model based on turbulent kinetic energy and turbulent dissipation rate, which is suitable for a high Reynolds number unseparated flow [25]. The k-ω model takes into account the compressibility of the flow and predict the propagation rate of the free shear flow, which is commonly used in the near-wall flow [26][27][28]. In this study, the SST k-ω model provided by commercial software CFX was selected.…”

Section: Numerical Simulation Strategymentioning

confidence: 99%

Investigations on Pressure Fluctuations in the S-Shaped Region of a Pump–Turbine

Wang

Gong

et al. 2021

Energies

Self Cite

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Hydraulic pumped storage is a special power generation and electricity shortage technology, which is usually operated with thermal power and nuclear power units, and plays a key role in ultra-high voltage and smart grid. Pressure fluctuations are the main reasons for the instability of the S-shaped region of pump–turbines, which seriously affects their lifespan and operation stability. To reveal the mechanism and propagation law of pressure fluctuations in the S-shaped region as well as numerical simulations at the turbine, the braking and the reverse pump operating conditions of a pump–turbine were carried out. Numerical results were validated using the performance experiments, and the generation mechanism and propagation law of pressure fluctuation were analyzed in detail. The analyses show that high-amplitude pressure fluctuations mainly occur in the braking and reverse pump operating conditions. Under the braking condition, a 0.49-fn low-frequency pressure fluctuation was captured, which is caused by the rotation of the backflow in the vanes. Under the reverse pump condition, a 0.19-fn low-frequency pressure fluctuation was confirmed, which is caused by the periodic rotation of the vortex between the vaneless space. This study has important guiding significance for practical engineering application.

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Effect mechanism of cavitation on the hump characteristic of a pump-turbine

Cited by 70 publications

References 16 publications

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

Effect of Flow Rate on Turbulence Dissipation Rate Distribution in a Multiphase Pump

Comparative Analysis of Strength and Modal Characteristics of a Full Tubular Pump and an Axial Flow Pump Impellers Based on Fluid-Structure Interaction

Investigations on Pressure Fluctuations in the S-Shaped Region of a Pump–Turbine

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