Due to their versatile design, Francis turbines are suitable for a wide range of pressures and flow rates. Due to this wide operating range, the Francis turbine is the most common type of hydroelectric turbine employed today. Francis turbines convert potential energy to mechanical energy. This type of turbine is classified as a reaction turbine, as it operates within a pressure system and relies upon a continuous body of water from the suction to pressure side of the turbine. Water is delivered through a pressurised water conductor known as a penstock. The water travels along the spiral case and passes through the guide vanes. The guide vanes convert the water’s potential energy to kinetic energy and can also be used to start, stop and regulate flow to the runner. The water enters the Francis runner radially, flowing from the outside to inside of the runner. The water is then discharged downwards, out of the base of the runner; this type of flow is known as axial flow due to the flow being in a parallel direction to the runner shaft.
