The whirl velocity of water at the inlet of the Kaplan turbine is 15 m/s. The velocity of water at inlet of the turbine is 20 m/s. Find the guide vane angle at inlet (In degrees).

Correct Answer: 41.41
cos (α1) = Vw1/ V1= 15/20 = ¾. Hence, α1 = cos-1(3/4) = 41.41o.