Details

Autor(en) / Beteiligte

• Feng, Jianjun
• Li, Wenfeng
• Luo, Xingqi
• Zhu, Guojun

Titel

Numerical analysis of transient characteristics of a bulb hydraulic turbine during runaway transient process

Ist Teil von

• Proceedings of the Institution of Mechanical Engineers. Part E, Journal of process mechanical engineering, 2019-08, Vol.233 (4), p.813-823

Ort / Verlag

London, England: SAGE Publications

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In this paper, the runaway transient process in a bulb turbine has been investigated by adopting commercial CFD code ANSYS CFX, and transient characteristics in the process have been examined and analyzed in detail. The results show that the predicted maximal runaway rotational speed and flow rate of the turbine are in close agreement with experimental data. During transient process, both the flow rate and rotational speed are rising with time, leading to an increase in both axial and circumferential velocities at the runner outlet. The velocity ratio between them has been diminished greatly at the draft tube inlet, inducing a spiral vortex rope growing with time. The cavitation will shorten the duration and reduce the maximal rotational speed of the runaway process. The runner blade pressure surface is much more critical to cavitation than the suction surface. The amplitude of pressure fluctuation in the runaway process is increasing in the main flow direction. Furthermore, the amplitude of pressure fluctuation reaches up to over 100% of the working head in the draft tube, considerably threatening the safe operation of the turbine.