Mechanical Engineering - Steam Nozzles and Turbines

Exercise :: Steam Nozzles and Turbines - Section 3

6. 

In a nozzle, the effect of supersaturation is to

A. decrease dryness fraction of steam
B. decrease specific volume of steam
C. increase the entropy
D. increase the heat drop

Answer: Option C

Explanation:

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7. 

Which of the following statement is correct?

A. The efficiency of steam turbines is greater than steam engines.
B. A flywheel is a must for steam turbine.
C. The turbine blades do not change the direction of steam issuing from the nozzle
D. The pressure of steam, in reaction turbines, is increased in fixed blades as well as in moving blades

Answer: Option A

Explanation:

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8. 

The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ number of stages are required.

A. more
B. less

Answer: Option B

Explanation:

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9. 

If the critical pressure ratio for steam is 0.546, then the steam is initially

A. wet steam
B. dry saturated steam
C. superheated steam
D. none of these

Answer: Option C

Explanation:

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10. 

Which of the following statement is wrong?

A. The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
B. The flowin the convergent portion of the nozzle is sub-sonic.
C. The flow in the divergent portion of the nozzle is super-sonic.
D. To increase the velocity of steam above sonic velocity (super-sonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary.

Answer: Option D

Explanation:

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