Theoretical Estimates of Rotordynamic Fluid Forces on a Front Shroud of Francis Turbine Caused by Leakage Flow

Haruka Nishimura; Kazuyasu Sugiyama; Yoshinobu Tsujimoto; Hajime Koyama

doi:10.5293/IJFMS.2018.11.3.344

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저널정보

한국유체기계학회
International Journal of Fluid Machinery and Systems 학술저널
International Journal of Fluid Machinery and Systems Vol.11 No.3
2018.9 344 - 356 (13page)
DOI : 10.5293/IJFMS.2018.11.3.344

저자정보

Haruka Nishimura (Osaka University)
Kazuyasu Sugiyama (Osaka University)
Yoshinobu Tsujimoto (Osaka University)
Hajime Koyama (Toshiba Energy Systems & Solutions Corporation)

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초록·키워드

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The rotordynamic fluid forces on a columnar rotor modeling the front shroud of Francis turbine caused by the leakage flow and whirling motion are evaluated by the experiments and the computations, to explain the self-excited vibration observed in free vibration tests. In addition to the leakage flow models previously proposed, a new model is proposed to include the effects of the rotation and whirling motion of the rotor to evaluate the rotordynamic fluid forces. After checking the validity of the models by comparisons with experiments and CFD, the characters of each component are discussed based on the physical mechanism producing the forces. It was found that the rotordynamic force component normal to the whirling orbit is mainly caused by the centrifugal forces of the added mass of the fluid in the clearance and that the tangential force is mainly caused by the acceleration of the axial leakage flow through the clearance.

#Rotordynamic Fluid Force #Whirling Motion #Francis Turbine #Columnar Rotor #Leakage Flow