3. Francis turbines

The Francis turbine has the widest range of applications. It can operate in a wide range of head conditions, from a few dozen meters up to 800 m. Unit power can reach considerable values, and there's no reason why we can't envisage groups of 1,000 MW or even more.

An example of a Francis turbine with a horizontal axis is shown in (figure 17 ).

On the one hand, in-depth hydraulic studies have enabled us to increase specific power and flow rates, improve efficiencies and impeller cavitation resistance, and gain in-depth knowledge of transient phenomena.