High-speed flow visualization in a pump-turbine under off-design operating conditions

Hasmatuchi, Vlad; Roth, Steven F.; Botero, Francisco; Avellan, François; Farhat, Mohamed

doi:10.1088/1755-1315/12/1/012059

Cited by 31 publications

(12 citation statements)

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“…Experimental research was conducted on the flow hydrodynamics of a low-specific-speed pump-turbine model under off-design operating conditions, including runaway and S-shaped turbine brake curves by [9,18]. they also performed high-speed flow visualizations in the vaneless space amongst the runner and the guide vanes as well as Wall pressure measurements in the stator.…”

Section: Experimental Studiesmentioning

confidence: 99%

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Review on S-Shape Characteristics of Pump Turbine for Hydropower Generation

Adu¹

2017

EPES

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This paper presents and discussed the results of an experimental investigation of S-shape characteristics of pump turbine. An experimental study of pump turbine has been carried out by many researchers to study its characteristics. By using the experimental results of tested pump of some previous researchers, The Numerical analysis and Experimental studies on the S-shaped characteristics of a pump turbine model, Impact of Parameters on S-shaped characteristics, mechanism of the internal flow of pump turbines as well as measurements of pressure fluctuations on reduced-scale model pump-turbines have been discussed.

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Section: Experimental Studiesmentioning

confidence: 99%

“…A lot has been dealt with on this phenomenon in many previous studies [18,19]. And experimental studies been done [20] to measure the characteristics of flow with the use of PIV and image processing technology.…”

Section: Experimental Analysis Of S-shape Characteristicsmentioning

confidence: 99%

Review on S-Shape Characteristics of Pump Turbine for Hydropower Generation

Adu¹

2017

EPES

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“…Backman (2008) and Sun et al (2012; predicted the distribution of pressure fluctuations in pump-turbines using 3D unsteady simulations. Hasmatuchi et al (2010; and Yan et al (2012) concluded that one stall cell rotating with the runner with subsynchronous rotating velocity was the main reason of flow separation and flow passages blockage. Similar results were also presented that there exists rotating-stall in the turbine brake operation of pump-turbines by Widmer et al (2011).…”

Section: Introductionmentioning

confidence: 99%

Fluid flow analysis of drooping phenomena in pump mode for a given guide vane setting of a pump-turbine model

Gong

Wang

et al. 2015

JZUS-A

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Abstract:The energy-discharge characteristics of pump-turbines in pump mode with a hump region are significantly important for operating stability. To investigate the flow characteristics, 3D steady numerical simulations are conducted for a given guide vane opening of 32 mm by solving Reynolds-averaged Navier-Stokes (RANS) equations using the shear-stress transport (SST) k-ω turbulence model. Based on the validation of computational fluid dynamics (CFD) results using experimental benchmarks, the part-load (0.45φ BEP ), drooping zone load (0.65φ BEP ), near best efficiency point (BEP) (0.90φ BEP ), BEP (1.00φ BEP ), and overload (1.24φ BEP ) regions are chosen to analyze how and why the fluid properties change in the runner. The causes of flow separation and spatial characteristics of flow at different load points are obtained through the analysis of flow angle and hydraulic losses. The results show that flow angle at the leading and trailing edge from the crown to the band distributes differently among these five operating points. Then, the reasons for drooping are investigated based on the Euler theory. It is found that drooping behavior comes from both the incidence/deviation effect and frictional losses. In addition, the runner losses are more consequential to drooping as shown by hydraulic loss analysis.

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“…The analysis of the pressure fluctuations resulting from the rotor-stator excitation showed that the rotating diametrical pressure mode and standing wave are properly simulated for a pump-turbine of 20 guide vanes and 9 impeller vanes. Besides the experimental measurements focusing on the flow through these two cascades [26,27], the numerical simulations combining pressure oscillations with mechanical properties have been carried out [28,29]. Lais et al (2008) also did experiments and simulation to study the natural frequencies, accompanying the fluid-structure interaction [30].…”

Section: Introductionmentioning

confidence: 99%

On the Flow Instabilities and Turbulent Kinetic Energy of Large-Scale Francis Hydroturbine Model at Low Flow Rate Conditions

et al. 2014

Advances in Mechanical Engineering

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This paper is to make a better understanding of the flow instabilities and turbulent kinetic energy (TKE) features in a largescale Francis hydroturbine model. The flow instability with aspect of pressure oscillation and pressure-velocity correlation was investigated using large eddy simulation (LES) method along with two-phase cavitation model. The numerical simulation procedures were validated by the existing experimental result, and further the TKE evolution was analyzed in a curvilinear coordinates. By monitoring the fluctuating pressure and velocities in the vanes' wake region, the local pressure and velocity variations were proven to have a phase difference approaching /2, with a reasonable cross-correlation coefficient. Also the simultaneous evolution of pressure fluctuations at the opposite locations possessed a clear phase difference of , indicating the stresses variations on the runner induced by pressure oscillation were in an odd number of nodal diameter. Considering the TKE generation, the streamwise velocity component ⟨ 2 ⟩ contributed the most to the TKE, and thus the normal stress production term and shear stress production term imparted more instability to the flow than other production terms.

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High-speed flow visualization in a pump-turbine under off-design operating conditions

Cited by 31 publications

References 1 publication

Review on S-Shape Characteristics of Pump Turbine for Hydropower Generation

Review on S-Shape Characteristics of Pump Turbine for Hydropower Generation

Fluid flow analysis of drooping phenomena in pump mode for a given guide vane setting of a pump-turbine model

On the Flow Instabilities and Turbulent Kinetic Energy of Large-Scale Francis Hydroturbine Model at Low Flow Rate Conditions

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