New & Renewable Energy (신재생에너지)

Korean Society for New and Renewable Energy (한국신·재생에너지학회)
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Loss Analysis by Impeller Blade Angle in the S-Curve Region of Low Specific Speed Pump Turbine

  • Ujjwal Shrestha (Graduate School, Department of Mechanical Engineering, Mokpo National University) ;
  • Young-Do Choi (Department of Mechanical Engineering, Institute of New and Renewable Energy Technology Research, Mokpo National University)
  • Received : 2024.05.03
  • Accepted : 2024.06.18
  • Published : 2024.06.25
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Abstract

A pump turbine is a technically matured option for energy production and storage systems. At the off-design operating range, the pump turbine succumbed to flow instabilities, which correlated with the pump turbine geometry. A low specific speed pump turbine was designed and modified according to the impeller blade angle. Reynolds-Average Navier-Stokes is carried out with a shear stress transport turbulence model to evaluate the detailed flow characteristics in the pump turbine. The impeller blade inlet angle (𝛽1) and outlet angle (𝛽2) are used to evaluate hydraulic loss in the pump turbine. When 𝛽1 changed from low to high value, the maximum efficiency is increased by 4.75% in turbine mode. The S-Curve inclination is reduced by 8% and 42% for changes in 𝛽1 and 𝛽2 from low to high values, respectively. At α = 21°, the shock loss coefficient (𝜁s) is reduced by 16% and 19% with increases of 𝛽1 and 𝛽2 from low to high values, respectively. When 𝛽1 and 𝛽2 values increased from low to high, the impeller friction coefficient (𝜁f) increased and decreased by 20% and 8%, respectively. Hence, the high 𝛽2 effectively reduced the loss coefficient and S-Curve inclination.

Keywords

References

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