Mechanical Engineering - Steam Nozzles and Turbines - Discussion

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

Answer: Option B

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.

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