Francis Turbine is a reaction Turbine, which was developed by English born American Engineer Sir J.B. Francis. The water enters the turbine through the outer periphery of the runner in the radial direction and leaves the runner in axial direction and hence it is called a mixed flow turbine. As the water flows to the runner, a part of pressure energy goes on changing into kinetic energy. Thus the water through the runner is under pressure. The runner is completely enclosed in an air tight casing and the casing & runner is always full of water.