Transient characteristics during the closure of guide vanes in a pump-turbine in pump mode

Li, Deyou; Wang, Hongjie; Li, Zhenggui; Nielsen, Torbjørn Kristian; Goyal, Rahul; Wei, Xianzhu; Qin, Daqing

doi:10.1016/j.renene.2017.10.088

Cited by 84 publications

(22 citation statements)

References 16 publications

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“…For example, Pavesi et al [28] conducted numerical simulations of a pump-turbine during the transient load following process in pump mode, and a full 3D flow structure was observed in the wicket gate channel, owing to boundary layer separation and stalling at lower rotational speeds. Li et al [29] simulated the transient guide vane closure process for a pump-turbine that was operated in pump mode, and confirmed that the dynamic instabilities that were observed at the end of the closure process originated from severe hydraulic variations that occurred in the guide vanes. Fu et al [30,31] discussed the energy conversion and dynamic instability of a pump-turbine during the transient load rejection process, and concluded that viscous dissipation effects of vortex flows in the tandem cascade regions mainly caused the dynamic instabilities and hydraulic losses.…”

Section: Introductionmentioning

confidence: 89%

Numerical Study on Flow Characteristics in a Francis Turbine during Load Rejection

et al. 2019

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Labyrinth seals are not usually included in the numerical models of hydraulic machinery to simplify the geometric modeling, and thereby reduce the calculation burden. However, this simplification affects the numerical results, especially in the load rejection process, because disc friction losses, volume losses, and pressure fluctuations in the seal ring (SR) clearance passage are neglected. This paper addresses the issue by considering all of the geometrical details of labyrinth seals when conducting multiscale flow simulations of a high head Francis turbine under a transient load rejection condition using the commercial software code. A comparison of the numerical results that were obtained with the experimental testing data indicates that the calculated values of both torque and mass discharge rate are 8.65% and 5% slightly less than the corresponding values that were obtained from experimental model testing, respectively. The obtained pressure fluctuations of the Francis turbine in the vaneless zone and the draft tube appear to more closely match with the experimental test data when including SR clearance. Moreover, the flow rates through SR clearance passages were very small, but the pressure fluctuations among them were significantly enhanced under the minimal load condition. The numerical model with SR clearance can more accurately reflect the fact that the water thrust on the runner only fluctuates from 800 N to 575 N during the load rejection process, even though the water thrust on the blades varies from −220 N to 1200 N. Therefore, multiscale flow study is of great significance in understanding the effect of clearance flow on the load rejection process in the Francis turbine.

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Section: Introductionmentioning

confidence: 89%

Numerical Study on Flow Characteristics in a Francis Turbine during Load Rejection

et al. 2019

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“…The turbulence model applied was the Shear Stress Transport (SST). This model is very accurate for the numerical investigation of flow within a centrifugal pump (Shojaeerd et al, 2012), also used by other authors, including Akemi et al (2015) and Li et al (2018) The fluid domain is a rotary domain with constant rotational speed of 1500 rpm. Therefore, all boundary rotated with this speed, except the inlet, which was stationary.…”

Section: Methodsmentioning

confidence: 99%

CFD simulation on centrifugal pump impeller with splitter blades

Rosa

Emerick

2020

Rev. bras. eng. agríc. ambient.

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The present paper aims to present the analysis and comparison of results of computational simulations using Computational Fluids Dynamics (CFD) in impellers of centrifugal pump. Three impellers were simulated: 1) original impeller, 2) original impeller with splitter blades at outlet; 3) original impeller with splitter blades at inlet. The splitters occupied 30% of the length of the main blades. They were simulated using the ANSYS-CFX software system in 1500 rpm rotational speed and at different flow rates. The turbulence model assumed was the Shear Stress Transport (SST). The results were used to build impeller blade head curves, besides the presentation of pressure distribution and streamline behaviour inside the impeller. It was verified that the insertion of the splitter blades reduced the impeller blade head, mainly the impeller with outlet splitter, whose reduction was more intense.

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“…This commercial software package is well validated and has a wide area of application. Examples of successful usage of this 3D-numerical code are the optimisation of turbine [35][36][37], intake structures [38,39], spillways [40], water-jet turbines [41], surge tank throttles [42], swirl generating devices [43] and also heat flux in photovoltaic system [44]. Key reasons for this decision are the adaptable post-processing as well as the very flexible meshing, which allows to include all needed details of the geometry in the spatial discretization.…”

Section: Numericsmentioning

confidence: 99%

Adaptation of an Existing Intake Structure Caused by Increased Sediment Level

Gabl

Gems

Birkner

et al. 2018

Water

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An unexpected and massive redistribution of fine sediment in a large Alpine reservoir was triggered by a further lowering of the water level to conduct maintenance work. This caused the need of a total redesign of the existing head race intake for a high head power plant in the Austrian Alps. Two main geometry options for the trash rack support structure are compared with numerical simulations (ANSYS-CFX) as well as with a scale model test (scale 1:20). The laboratory experiment substantially benefited from the preliminary numerical investigation in respect of the location and implementation of the model boundaries. In return was the confidence in the numerics strengthened by the successful validation of the local head loss and the velocity distribution for the main operation cases. This allowed that the main inputs for the structural design and the further optimisation is conducted only with the 3D-numerical tool. The paper presents the interlaced concept as well as the main finding of the investigation, which lead to a successful adaptation of the intake structure.

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Transient characteristics during the closure of guide vanes in a pump-turbine in pump mode

Cited by 84 publications

References 16 publications

Numerical Study on Flow Characteristics in a Francis Turbine during Load Rejection

Numerical Study on Flow Characteristics in a Francis Turbine during Load Rejection

CFD simulation on centrifugal pump impeller with splitter blades

Adaptation of an Existing Intake Structure Caused by Increased Sediment Level

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