# Mechanical Engineering - Steam Nozzles and Turbines - Discussion

### Discussion :: Steam Nozzles and Turbines - Section 1 (Q.No.13)

13.

The efficiency of reaction turbine is maximum when (where α = Angle made by the absolute velocity (V) at inlet)

 [A]. Vb = 0.5 V cos α [B]. Vb = V cos α [C]. Vb = 0.5 V2 cos α [D]. Vb = V2 cos α

Explanation:

No answer description available for this question.

 Saikumar said: (Mar 12, 2015) Velocity ratio for impulse turbine = 0.5 cosθ. Velocity ratio for reaction turbine = cosθ.

 Yashfa said: (Jul 23, 2016) How is this possible?

 Pal said: (Aug 19, 2016) The answer should be the option (a).

 N Suresh said: (Dec 6, 2016) When the efficiency of reaction turbine is maximum where blade velocity should be half. So that Vb = 0.5 V cos a.

 Vijay said: (Dec 22, 2016) Maximum efficiency is option B because (Vb/v)= cos.

 Biplab said: (Dec 31, 2016) For reaction turbine, max efficiency condition is cos alpha and in case of impulse turbine (cos alpha)/2.

 K910 said: (Feb 7, 2020) The answer is correct for rxn it is U/V=cos alpha for impulse it is cos(alpa)/2.