CFD configurations for hydraulic turbine startup

This paper presents various numerical setups for modelling Francis turbine startups involving moving meshes and variable runner speed in order to help define best practices. During the accelerating phase of the startup, the flow is self-similar between channels, thus making single sector configuration appropriate. Adding the draft tube improves the results by allowing pressure recovery midway during in the startup. At the speed no-load regime, a rotating stall phenomenon occurs and can only be capted with the full runner included in the simulation. Comparison with experimental data, such as runner speed and strain gauge measurements, generally shows good agreement.