Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope

C. Landry, A. Favrel, A. Müller, K. Yamamoto, S. Alligné, F. Avellan

研究成果: Conference article査読

1 被引用数 (Scopus)

抄録

At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of these operating conditions requires a numerical pipe model taking into account the complexity of the two-phase flow. Among the hydroacoustic parameters describing the cavitating draft tube flow in the numerical model, the mass flow gain factor, representing the mass excitation source expressed as the rate of change of the cavitation volume as a function of the discharge, remains difficult to model. This paper presents a quasi-static method to estimate the mass flow gain factor in the draft tube for a given cavitation vortex rope volume in the case of a reduced scale physical model of a ν = 0.27 Francis turbine. The methodology is based on an experimental identification of the natural frequency of the test rig hydraulic system for different Thoma numbers. With the identification of the natural frequency, it is possible to model the wave speed, the cavitation compliance and the volume of the cavitation vortex rope. By applying this new methodology for different discharge values, it becomes possible to identify the mass flow gain factor and improve the accuracy of the system stability analysis.

本文言語English
論文番号012022
ジャーナルJournal of Physics: Conference Series
813
1
DOI
出版ステータスPublished - 2017 4 4
外部発表はい
イベントHYdropower Plants PERformance and FlexiBle Operation Towards Lean Integration of New Renewable Energies Symposium, HYPERBOLE 2017 - Porto, Portugal
継続期間: 2017 2 22017 2 3

ASJC Scopus subject areas

  • 物理学および天文学(全般)

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