Investigation of pressure fluctuation and pulsating hydraulic axial thrust in Francis turbines

Xing Zhou, Changzheng Shi, Kazuyoshi Miyagawa, Hegao Wu, Jinhong Yu, Zhu Ma

Research output: Contribution to journalArticlepeer-review

Abstract

Under the circumstances of rapid expansion of diverse forms of volatile and intermittent renewable energy sources, hydropower stations have become increasingly indispensable for improving the quality of energy conversion processes. As a consequence, Francis turbines, one of the most popular options, need to operate under off-design conditions, particularly for partial load operation. In this paper, a prototype Francis turbine was used to investigate the pressure fluctuations and hydraulic axial thrust pulsation under four partial load conditions. The analyses of pressure fluctuations in the vaneless space, runner, and draft tube are discussed in detail. The observed precession frequency of the vortex rope is 0.24 times that of the runner rotational frequency, which is able to travel upstream (from the draft tube to the vaneless space). Frequencies of both 24.0 and 15.0 times that of the runner rotational frequency are detected in the recording points of the runner surface, while the main dominant frequency recorded in the vaneless zone is 15.0 times that of the runner rotational frequency. Apart from unsteady pressure fluctuations, the pulsating property of hydraulic axial thrust is discussed in depth. In conclusion, the pulsation of hydraulic axial thrust is derived from the pressure fluctuations of the runner surface and is more complicated than the pressure fluctuations.

Original languageEnglish
Article number1734
JournalEnergies
Volume13
Issue number7
DOIs
Publication statusPublished - 2020 Apr 1

Keywords

  • Francis turbine
  • Hydraulic axial thrust
  • Numerical simulation
  • Partial load operation
  • Pressure fluctuation

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Energy (miscellaneous)
  • Control and Optimization
  • Electrical and Electronic Engineering

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