Nature of the Prime force
When we move from Pelton to Kaplan the force producing mechanism changes from impulse to reaction.
Suitability of Pelton, Francis and Kaplan turbines
In Pelton pure impulse force of the water jet is responsible for the rotation of the impeller. Water stored at high altitude can produce high impose force due to its high velocity. So Pelton turbines are suitable for operation when water energy is available at high head and low flow rate.
- Head = 2-25 m
- Flow rate = 70-800 m3/s
- Head = 45-400 m
- Flow rate = 10-700 m3/s
Turbine Selection graph
The following graph gives a clear idea about when to use which turbine depending upon the available water head and flow rate. It is obvious that Francis turbine covers a wide range of operating conditions or they can work efficiently under wide range of operating conditions.