Water turbine is a machine which is converts hydraulic energy into mechanical energy. Turbine when coupled to an alternator (electrical generator) electricity is produced this is called hydel power.
Water turbines are classified into two types they are Impulse turbine and reaction turbine on action of water on blades. Impulse turbine works under the impulse effect or impact of jet on blades due to kinetic energy in it. Impulse turbine is also known as velocity turbine.
Reaction turbine works under the pressure energy and adopts principle of reaction force. Reaction turbine is known as a pressure turbine.
Direction of flow
Depending on the direction of flow of water on turbine runner, the turbines are classified as.
- Axial flow turbines
- Radial flow turbines
- Tangential flow turbines
- Mixed flow turbines
Francis turbine is an inward flow reaction turbine. Kaplan turbine is axial flow type and Pelton wheel is tangential flow type turbine.
Impulse turbine is used for high heads and they do not require draft tubes at their exit end. The wheel should not be run full and they do not require air tight casing. Flow of water can be easily regulated. The water may be admitted over a part of perimeter.