Mechanical Engineering - Steam Nozzles and Turbines

Exercise :: Steam Nozzles and Turbines - Section 3

31. 

The blade friction in the impulse turbine reduces the velocity of steam by __________ while it passes over the blades.

A. 10 to 15%
B. 15 to 20%
C. 20 to 30%
D. 30 to 40%

Answer: Option A

Explanation:

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32. 

The effect of bleeding is that

A. it increases the thermodynamic efficiency of the turbine
B. boiler is supplied with hot water
C. it decreases the power developed by the turbine
D. all of the above

Answer: Option D

Explanation:

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33. 

The expansion of steam, as it flows over the blades in reaction turbine, represents

A. isothermal process
B. isentropic process
C. throttling process
D. free-expansion process

Answer: Option B

Explanation:

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34. 

The critical pressure ratio for initially superheated steam is __________ as compared to initially dry saturated steam.

A. more
B. less

Answer: Option B

Explanation:

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35. 

For a Parson's reaction turbine, if α1 and α2 are fixed blade angles at inlet and exit respectively and β1 and β2 are the moving blade angles at entrance and exit respectively, then

A. α1 = α2 and β1 = β2
B. α1 = β1 and α2 = β2
C. α1 < β1 and α2 > β2
D. α1 = β2 and β1 = α2

Answer: Option D

Explanation:

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