Computational cavitating viscous liquid flows in a pump as turbine and Reynolds number effects

Li, Wenguang; Zhang, Yuliang

doi:10.1177/0954408918770057

Cited by 4 publications

(5 citation statements)

References 34 publications

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“…The cavitation wa more prone to appear in the pump impeller under high viscosity conditions. Li and Zhan [24] also found that an increased viscosity was favorable to cavitation in a pump as th turbine. The cavitation number, σa, is one of the important parameters characterizing the cav itation of the pump.…”

Section: Cavitation Characteristic Curve Of Hampmentioning

confidence: 95%

“…The cavitation was more prone to appear in the pump impeller under high viscosity conditions. Li and Zhang [24] also found that an increased viscosity was favorable to cavitation in a pump as the turbine. Under the NPSHAC condition, the NPSHA under different fluid viscosities is show in Figure 7.…”

Section: Cavitation Characteristic Curve Of Hampmentioning

confidence: 96%

“…The fluids used in the present simulation were machine oils that have been employed by Li [14] and Li and Zhang [24]. Their density, kinematic viscosity, saturated vapor pressure, and surface tension are shown in Table 3.…”

Section: Numerical Schemementioning

confidence: 99%

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Influence of Fluid Viscosity on Cavitation Characteristics of a Helico-Axial Multiphase Pump (HAMP)

Zhao

et al. 2022

Energies

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Fluid viscosity is one of the key factors affecting the cavitation characteristics of the Helico-axial Multiphase Pump (HAMP). In this paper, fluids with viscosities of 24.46 mm2/s, 48.48 mm2/s, 60.70 mm2/s, and 120.0 mm2/s were investigated by numerical simulation. The Ansys Fluent software was employed to conduct the simulation. The mixture multiphase flow model and the RNG k-ε turbulence model were adopted. The Singhal cavitation model was employed to consider the effects of the non-condensable gas on cavitation. An experiment was carried out to validate the numerical method. The results showed that the Net Positive Suction Head-available (NPSHA) of the pump decreased as the fluid viscosity increased. Under the critical NPSHA condition, the NPSHA decreased from 5.11 m to 3.68 m as the fluid viscosity increased from 24.46 mm2/s to 120.0 mm2/s. This suggested that the cavitation performance of the pump was deteriorated under high fluid viscosity. The impeller passage area occupied by the vapor increased when the fluid viscosity increased. Nearly half of the flow passages were occupied by cavitation bubbles when the fluid viscosity increased to 120.0 mm2/s. The vapor volume fraction, both on the suction surface and pressure surface of the blade, increased with the fluid viscosity. The vapor on the suction surface was mainly distributed in the region with the streamwise between 0 and 0.36 when the fluid viscosity was 24.46 mm2/s; while the high vapor volume fraction range increased to the streamwise of 0.42 when the fluid viscosity increased to 120.0 mm2/s. The higher vapor volume fraction corresponded with the lower pressure. It was also found that the turbulent kinetic energy, both on the suction surface and pressure surface, increased with the fluid viscosity, which was the favorite for producing more cavitation bubbles. Furthermore, the maximum velocity area was mainly concentrated in the inlet area of the impeller. The velocity distribution in the impeller was basically the same with the viscosity of 24.46 mm2/s and 48.48 mm2/s. When the viscosity further increased to 60.70 mm2/s, the maximum velocity area in the impeller was relatively large. This study provides a reference for designing the HAMP.

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Section: Cavitation Characteristic Curve Of Hampmentioning

confidence: 95%

Section: Cavitation Characteristic Curve Of Hampmentioning

confidence: 96%

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Influence of Fluid Viscosity on Cavitation Characteristics of a Helico-Axial Multiphase Pump (HAMP)

Zhao

et al. 2022

Energies

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“…CFD technology has been found to be effective for analyzing the cavitation zone and associated decreases in inefficiency. The validation of models with the prevailing outcomes allows researchers to redesign, select, and forecast performance [221]. Among the models applied by CFD, Rayleigh-Plesset is the leading model for modeling and prediction of many characteristics of cavitation including the formation, decay, and vapor production rate [222].…”

Section: State-of-the-art Assessment and Evaluationmentioning

confidence: 99%

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

Yaseen‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

Ameen

Aldlemy

et al. 2020

Sustainability

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Dam and powerhouse operation sustainability is a major concern from the hydraulic engineering perspective. Powerhouse operation is one of the main sources of vibrations in the dam structure and hydropower plant; thus, the evaluation of turbine performance at different water pressures is important for determining the sustainability of the dam body. Draft tube turbines run under high pressure and suffer from connection problems, such as vibrations and pressure fluctuation. Reducing the pressure fluctuation and minimizing the principal stress caused by undesired components of water in the draft tube turbine are ongoing problems that must be resolved. Here, we conducted a comprehensive review of studies performed on dams, powerhouses, and turbine vibration, focusing on the vibration of two turbine units: Kaplan and Francis turbine units. The survey covered several aspects of dam types (e.g., rock and concrete dams), powerhouse analysis, turbine vibrations, and the relationship between dam and hydropower plant sustainability and operation. The current review covers the related research on the fluid mechanism in turbine units of hydropower plants, providing a perspective on better control of vibrations. Thus, the risks and failures can be better managed and reduced, which in turn will reduce hydropower plant operation costs and simultaneously increase the economical sustainability. Several research gaps were found, and the literature was assessed to provide more insightful details on the studies surveyed. Numerous future research directions are recommended.

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“…Cavitation is an important source of instabilities, so it was included in the same query as instabilities. In this group, the following topics are addressed: geometry, efficiency, cavitation [4,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], flow structures [8,[22][23][24][25], pressure fluctuations [16,21,26,27], vortex rope [27], energy losses when switching from pump to turbine mode [28], and application of entropy production theory for energy losses [29]. None of them addresses the measurement of instabilities.…”

Section: Introductionmentioning

confidence: 99%

Periodic Instabilities in a Specific Low-Speed Pump Working as a Turbine

Bolaños¹,

Botero²

2023

Advances in Turbomachinery

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The hydrodynamic instabilities in a turbomachine can be divided into two main groups: periodic (or quasi-periodic) and nonperiodic. And the total instability, calculated from a statistical parameter with linear characteristics, such as variance, can be defined as the sum of periodic and nonperiodic instabilities. Based on the above, the main objective of the study was to estimate the periodic instabilities in a pump operating as a turbine. For this purpose, pressure fluctuation signals from sensors installed on the turbomachine volute and spaced 135° apart were used. The signals were analyzed in the time and frequency domain to identify, initially, the periodic instabilities and their relationship with the spectral components and, subsequently, to estimate the magnitude of these instabilities as the variance of the filtered series in the spectral band related to the periodic instability. In addition, the study aims to establish the contribution of periodic instabilities to total instability.

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Computational cavitating viscous liquid flows in a pump as turbine and Reynolds number effects

Cited by 4 publications

References 34 publications

Influence of Fluid Viscosity on Cavitation Characteristics of a Helico-Axial Multiphase Pump (HAMP)

Influence of Fluid Viscosity on Cavitation Characteristics of a Helico-Axial Multiphase Pump (HAMP)

State-of-the Art-Powerhouse, Dam Structure, and Turbine Operation and Vibrations

Periodic Instabilities in a Specific Low-Speed Pump Working as a Turbine

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