The pressure fluctuation taking place at the whole passage of a prototype Francis hydraulic turbine is studied by carrying out both experimental and numerical simulation. Unsteady wall pressure measurements at six different typical operating conditions are performs to thoroughly investigate pressure fields in the spiral case and straight draft tube dynamically. 3-D unsteady turbulent simulations are performed and compared to the experimental data. The computed flow domain includes the spiral case, stay vanes, guide vanes, rotating runner and the draft tube. The characteristic of unsteady flow and the pressure pulsation as well as their relationships are discussed in this paper, which also analyzed the correlation between the unsteady flow pattern and the pressure fluctuation at different parts of the turbine. In order to optimize the internal flow distribution in Francis turbines at partial loads, this paper presents some preliminary methods to control the unsteady flow pattern.

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