Mechanical Engineering - Steam Nozzles and Turbines - Discussion


The critical pressure ratio for initially wet steam is

[A]. 0.546
[B]. 0.577
[C]. 0.582
[D]. 0.601

Answer: Option C


No answer description available for this question.

Lakshmi Kant said: (Jan 17, 2014)  
The critical pressure ratio in nozzles for max. discharge is,

{P2/P1}= [2/(n+1)]^{n/(n-1)}.

For saturated steam, n= 1.135.

Therefore, P2/P1 = [2/2.135]^(1.135/0.135).
= 0.58.

Clearly for wet steam, it will be slightly more than the above value. Hence, for wet steam,

P2/P1 = 0.582.

Raj said: (Feb 24, 2014)  
For wet steam n1=1.132,
For super heated steam n2=1.35.

So n2>n1
Then value of p2/p1 will decrease from n1 to n2.

Saikumar said: (Mar 12, 2015)  
The answer is coming as 0.577 and 0.5776 by substituting above values.

Saikumar said: (Mar 12, 2015)  
Steam where most of the process occurs in the wet region: n = 1.135.

Steam super heated: n = 1.30.

Air: n = 1. 4.

Methane: n = 1.31.

Helium: n = 1.667.

Dheena said: (Jul 7, 2015)  
What is n?

Sharad said: (Jul 19, 2016)  
N is the indix for steam.
N for superheated steam is 1.135.
N for dry saturated steam is 1.3.
Then N for wet steam is?

Raviraj said: (Dec 9, 2016)  
The answer is 0.577 as for wet stream n=1.135.

Vijay said: (Dec 22, 2016)  
The critical pressure ratio is 0.58 because n= 1.135 for wet steam and critical pressure formula is given above.

Balu said: (Aug 20, 2017)  
The Exact answer is 0.577.

Raju said: (Nov 14, 2017)  
What is the value of n when steam is wet?

Cr7 said: (Feb 5, 2018)  
n means? Explain it.

Sohan said: (Aug 28, 2018)  
Superheated or supersaturated=0.546.
Dry saturated=0.578.

Mani Selvan said: (Jul 26, 2019)  
For wet steam n=1.113.

If substituted in eqn p2/p1=(2/n+1)^(n/n-1), we get p2/p1= 0.581963802, which is approximately equal to 0.582.

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