3.2.1 Reaction turbine
In a reaction turbine, the runners are fully immersed in water
and are enclosed in a pressure casing. The runner blades are
angled so that pressure differences across them create lift
forces, like those on aircraft wings, and the lift forces cause
the runner to rotate [5]. The casing is scrolled to distribute
water around the entire perimeter of the runner hence the
runner and the casing are carefully engineered so that the
clearance between them is minimized. Examples of reaction
turbines are the Francis and Kaplan type of turbines.