PRESSURE PULSATION IN THE STATIONARY AND ROTATING SYSTEM OF A HIGH SPECIFIC SPEED KAPLAN PIT-TYPE TURBINE – CFD-SIMULATIONS AND EXPERIMENTAL VERIFICATION

Research output: Contribution to conferencePaperResearchpeer-review

Abstract

Power generation in irrigation channels and at other low head locations becomes more interesting due to the still increasing demand for green energy. For these applications a low-cost standardised turbine concept was developed with a high specific speed Kaplan pit-type turbine with a belt drive as core component. The horizontal axis 3-blade runner with a nominal specific speed in the best efficiency point of nq = 230 rpm has such a flat characteristic that operation with nq = 260 rpm practically provides the same peak efficiency. The optimisation of the runner was realised by means of CFD with a special focus on the unfavourably high susceptibility of cavitation for such a high specific speed unit. As the built-in situation is very variable and as the encasing of the turbine in concrete is not guaranteed, the structure itself must be stiff and able to resist all possible load cases. Pressure pulsations during the operation are of special interest.
The design of the turbine was tested during a model test according to IEC 60193[1] with a nominal runner diameter of D = 0.3 m. The measurements of the pressure pulsation were realised for selected operation points with 24 pressure transmitters in total, whereas 8 transmitters were located in the stationary system in the draft tube conus and 16 transmitters were located on both, the pressure and the suction side of a blade in the rotating system. A telemetry system transferred the signal from the rotating runner to the measurement system. The numerical model comprises mainly structured meshes of all components, including the intake with the pit, a 360 degree model of the distributer for different wicket gate positions, the complete runner for different positions, the draft tube and the tail water downstream. A loss analysis for each of the components was monitored during the solver run, to verify the convergence for different mesh qualities and different operation points of these pre-calculations in stationary mode [2]. Afterwards transient simulations were realised with a scale resolving turbulence model for different operation points for more than 10 revolutions of the runner and a small time-step.
The pressure pulsations show a clear influence of the pit on the rotating runner blades as well as pressure pulsations downstream of the runner and an interaction with the draft tube.
LanguageEnglish
PagesCMFF18-074
StatusPublished - 7 Sep 2018
Event2018 Conference on Modelling Fluid Flow - Hotel Gellert, Budapest, Hungary
Duration: 4 Sep 20187 Sep 2018

Conference

Conference2018 Conference on Modelling Fluid Flow
Abbreviated titleCMFF 18
CountryHungary
CityBudapest
Period4/09/187/09/18

Fingerprint

Computational fluid dynamics
Turbines
Transmitters
Belt drives
Telemetering
Turbulence models
Irrigation
Cavitation
Power generation
Numerical models
Concretes
Costs
Water

Fields of Expertise

  • Sustainable Systems

Treatment code (Nähere Zuordnung)

  • Experimental

Cite this

PRESSURE PULSATION IN THE STATIONARY AND ROTATING SYSTEM OF A HIGH SPECIFIC SPEED KAPLAN PIT-TYPE TURBINE – CFD-SIMULATIONS AND EXPERIMENTAL VERIFICATION. / Benigni, Helmut; Schiffer-Rosenberger, Jürgen; Bodner, Christian; Jaberg, Helmut.

2018. CMFF18-074 Paper presented at 2018 Conference on Modelling Fluid Flow , Budapest, Hungary.

Research output: Contribution to conferencePaperResearchpeer-review

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abstract = "Power generation in irrigation channels and at other low head locations becomes more interesting due to the still increasing demand for green energy. For these applications a low-cost standardised turbine concept was developed with a high specific speed Kaplan pit-type turbine with a belt drive as core component. The horizontal axis 3-blade runner with a nominal specific speed in the best efficiency point of nq = 230 rpm has such a flat characteristic that operation with nq = 260 rpm practically provides the same peak efficiency. The optimisation of the runner was realised by means of CFD with a special focus on the unfavourably high susceptibility of cavitation for such a high specific speed unit. As the built-in situation is very variable and as the encasing of the turbine in concrete is not guaranteed, the structure itself must be stiff and able to resist all possible load cases. Pressure pulsations during the operation are of special interest.The design of the turbine was tested during a model test according to IEC 60193[1] with a nominal runner diameter of D = 0.3 m. The measurements of the pressure pulsation were realised for selected operation points with 24 pressure transmitters in total, whereas 8 transmitters were located in the stationary system in the draft tube conus and 16 transmitters were located on both, the pressure and the suction side of a blade in the rotating system. A telemetry system transferred the signal from the rotating runner to the measurement system. The numerical model comprises mainly structured meshes of all components, including the intake with the pit, a 360 degree model of the distributer for different wicket gate positions, the complete runner for different positions, the draft tube and the tail water downstream. A loss analysis for each of the components was monitored during the solver run, to verify the convergence for different mesh qualities and different operation points of these pre-calculations in stationary mode [2]. Afterwards transient simulations were realised with a scale resolving turbulence model for different operation points for more than 10 revolutions of the runner and a small time-step.The pressure pulsations show a clear influence of the pit on the rotating runner blades as well as pressure pulsations downstream of the runner and an interaction with the draft tube.",
author = "Helmut Benigni and J{\"u}rgen Schiffer-Rosenberger and Christian Bodner and Helmut Jaberg",
year = "2018",
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AU - Schiffer-Rosenberger, Jürgen

AU - Bodner, Christian

AU - Jaberg, Helmut

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N2 - Power generation in irrigation channels and at other low head locations becomes more interesting due to the still increasing demand for green energy. For these applications a low-cost standardised turbine concept was developed with a high specific speed Kaplan pit-type turbine with a belt drive as core component. The horizontal axis 3-blade runner with a nominal specific speed in the best efficiency point of nq = 230 rpm has such a flat characteristic that operation with nq = 260 rpm practically provides the same peak efficiency. The optimisation of the runner was realised by means of CFD with a special focus on the unfavourably high susceptibility of cavitation for such a high specific speed unit. As the built-in situation is very variable and as the encasing of the turbine in concrete is not guaranteed, the structure itself must be stiff and able to resist all possible load cases. Pressure pulsations during the operation are of special interest.The design of the turbine was tested during a model test according to IEC 60193[1] with a nominal runner diameter of D = 0.3 m. The measurements of the pressure pulsation were realised for selected operation points with 24 pressure transmitters in total, whereas 8 transmitters were located in the stationary system in the draft tube conus and 16 transmitters were located on both, the pressure and the suction side of a blade in the rotating system. A telemetry system transferred the signal from the rotating runner to the measurement system. The numerical model comprises mainly structured meshes of all components, including the intake with the pit, a 360 degree model of the distributer for different wicket gate positions, the complete runner for different positions, the draft tube and the tail water downstream. A loss analysis for each of the components was monitored during the solver run, to verify the convergence for different mesh qualities and different operation points of these pre-calculations in stationary mode [2]. Afterwards transient simulations were realised with a scale resolving turbulence model for different operation points for more than 10 revolutions of the runner and a small time-step.The pressure pulsations show a clear influence of the pit on the rotating runner blades as well as pressure pulsations downstream of the runner and an interaction with the draft tube.

AB - Power generation in irrigation channels and at other low head locations becomes more interesting due to the still increasing demand for green energy. For these applications a low-cost standardised turbine concept was developed with a high specific speed Kaplan pit-type turbine with a belt drive as core component. The horizontal axis 3-blade runner with a nominal specific speed in the best efficiency point of nq = 230 rpm has such a flat characteristic that operation with nq = 260 rpm practically provides the same peak efficiency. The optimisation of the runner was realised by means of CFD with a special focus on the unfavourably high susceptibility of cavitation for such a high specific speed unit. As the built-in situation is very variable and as the encasing of the turbine in concrete is not guaranteed, the structure itself must be stiff and able to resist all possible load cases. Pressure pulsations during the operation are of special interest.The design of the turbine was tested during a model test according to IEC 60193[1] with a nominal runner diameter of D = 0.3 m. The measurements of the pressure pulsation were realised for selected operation points with 24 pressure transmitters in total, whereas 8 transmitters were located in the stationary system in the draft tube conus and 16 transmitters were located on both, the pressure and the suction side of a blade in the rotating system. A telemetry system transferred the signal from the rotating runner to the measurement system. The numerical model comprises mainly structured meshes of all components, including the intake with the pit, a 360 degree model of the distributer for different wicket gate positions, the complete runner for different positions, the draft tube and the tail water downstream. A loss analysis for each of the components was monitored during the solver run, to verify the convergence for different mesh qualities and different operation points of these pre-calculations in stationary mode [2]. Afterwards transient simulations were realised with a scale resolving turbulence model for different operation points for more than 10 revolutions of the runner and a small time-step.The pressure pulsations show a clear influence of the pit on the rotating runner blades as well as pressure pulsations downstream of the runner and an interaction with the draft tube.

M3 - Paper

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