pelton francis and kaplan are the most commonly used hydraulic turbines in this video we will compare these three turbines and see when to use which turbine when we move from pelton to kaplan the force producing mechanism changes from impulse to reaction in peltin pure impulse force of water jet is responsible for rotation of impeller water stored at high altitude can produce high impulse force due to its high velocity so pelt and turbine are suitable for operation when water energy is available at high head and low flow rate whereas kaplan turbine is suitable for the reverse
case a high water flow will guarantee efficient production of reaction force so when water is available at high flow rate and low head kaplan turbine is the best choice francis turbine comes in between for medium head to medium flow rate applications francis turbine is not a pure reaction turbine a portion of force comes from impulse action also this graph gives a clear idea about when to use which turbine depending upon available water head and flow rate it is obvious that francis turbine covers a wide range of operating conditions or they can work efficiently in wide
range of operating conditions this is why francis turbine is the most preferred hydraulic turbine if you use a turbine out of its recommended operating range it will work but less efficiently it is also interesting to note the direction of fluid flow with respect to axis of rotation in each case
