Experimental investigation on a high head model Francis turbine during load rejection

Goyal, Rahul; Bergan, Carl Werdelin; Cervantes, Michel; Gandhi, Bhupendra K.; Dahlhaug, Ole Gunnar

doi:10.1088/1755-1315/49/8/082004

Cited by 14 publications

(25 citation statements)

References 6 publications

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“…The numerical validation on corresponding hydroturbine models has been performed and great insights on the formation of RVR at lower operating conditions have been presented in several numerical studies. Understanding the nature and formation of RVR is important to mitigate its effects on the turbine [5]. The formation of 'snake' like RVR happens mainly due to the deceleration of the swirling flow in the draft tube [5,6].…”

Section: Authorsmentioning

confidence: 99%

“…However, in case of load decrease, i.e., from BEP to PL, the formation of a very low-frequency signal that had a dominating effect was observed. The formation of a very lowfrequency signal inside the draft tube is associated with the formation of rotating vortex rope (RVR) and leads to flow instabilities [4][5][6]. Similar studies about pressure pulsations in the draft tube were performed on FLINDT project Francis turbine [8], Kaplan prototype turbine [9], and pump as turbine (PAT) working in pump mode [10].…”

Section: Introductionmentioning

confidence: 99%

“…Also, their ability to produce clean output energy could counter the adversity caused by limited resources. Among such renewable energy resources, the use of hydraulic turbines is the most favoured technique for power production [1][2][3][4][5]. Hydroturbines can operate at varying operating loads that make it a relatively superior technology when compared to other alternative renewable resources-based technologies.…”

Section: Introductionmentioning

confidence: 99%

“…The water is then released back to nature. Though hydro-turbines are designed to operate at best efficiency point (BEP), varying energy demands in recent years imply a flexible operation of hydraulic turbines [1][2][3][4][5]. This means that the efficiency of the turbine should not be largely compromised in off-design conditions, which is not the actual case today [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

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Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Joy¹,

Cervantes²,

Raisee³

2021

IJFMS

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In the present study, a reduced model of the Francis-99 model turbine was investigated numerically at part load operating condition. The reduced model consists of a standalone draft tube domain of the Francis-99 model turbine. Numerical studies performed in the past on nearly complete hydro-turbine models (inclusive of the spiral casing, distributor domains, runner, and draft tube) reportedly consist of a large number of computational grids. This may increase the computational costs and data storage required to perform numerical analysis, which could be a setback for future research on new design concepts and optimization study of the draft tube domain. The reduced model was developed by mapping the phase averaged axial, radial, and tangential velocity profiles from the runner exit to the inlet of the standalone draft tube domain. Additionally, turbulent kinetic energy (k) and turbulent eddy dissipation (ε) variables were also considered for better flow prediction inside the draft tube domain. Two methods for mapping inlet boundary conditions were considered in the present study. In the first method, the entire planar profile of the runner-draft tube interface was considered. In the second method, the variables along a radial profile at the runner exit were considered with an axissymmetric flow assumption over the entire draft tube inlet plane. The numerical results obtained from the Francis-99 reduced model turbine were validated against the numerical model of the NVKS Francis-99 model turbine (with available structured mesh) that was also analysed using the passage flow numerical technique and available experimental results. The results were found to be in reasonable agreement, with each other. The present study could be useful for the future mitigation study of rotating vortex rope by modifying the draft tube domain.

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Section: Authorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Joy¹,

Cervantes²,

Raisee³

2021

IJFMS

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“…Pressure vessels have been in use as a compressed air receivers, pressure reactors, pressure filters, and hot water storage tanks. However, these vessels have been found to be used in hydraulic turbines erosion test rigs to stabilize the inlet pressure head and also to stabilize the flow in the pipes [2] [3]. The hydraulic turbine test facility designed and constructed based on IEC standard also employ these vessels to ensure uniform velocity profile and to decrease turbulence [4] [5].…”

Section: Introductionmentioning

confidence: 99%

Pressure fluctuation measurement in pressure vessels

Kapali

Neopane

Chitrakar

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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Pressure vessels are mechanical devices that act as a reservoir of fluids at pressure more or less than atmospheric pressure. This research focuses on the application of the pressure vessel for hydraulic testing of hydro turbines to maintain uniform velocity profile and to suppress the pressure surge in the pipeline. An initial assumption for the design of a thin-walled horizontal type pressure vessel with the ellipsoidal type of head is based on the mathematical relations as per ASME code, Section VIII, Division I, for an operating pressure of 0.3 MPa and design pressure of 0.6 MPa. The pressure vessel has been placed, close to outlet of the main pump to prevent the water hammering in the pipeline. The measurement of the pressure fluctuations at the inlet, outlet, and inside of the vessel, due to the dynamic action of fluid forced by the pump are recorded. The study attempts to relate the use of pressure vessels to generate stable flow and pressure at the outlet for hydraulic testing of turbines.

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Review of hydrodynamics instabilities in Francis turbine during off-design and transient operations

2018

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Experimental investigation on a high head model Francis turbine during load rejection

Cited by 14 publications

References 6 publications

Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Reduced Numerical Modeling of a High Head Francis Turbine Draft Tube at Part Load

Pressure fluctuation measurement in pressure vessels

Review of hydrodynamics instabilities in Francis turbine during off-design and transient operations

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