The whirl velocity at inlet of Francis turbine is given to be 20 m/s. The blade velocity is given as 35 m/s. What is the hydraulic efficiency for a head of 100 m?

Correct Answer: 70%
The hydraulic efficiency of a Francis turbine is given by ηh = Vw1.u1/ gH. Substituting the values of the given parameters in the equation, we get hydraulic efficiency = 70%.