Steam Nozzles and Turbines problems
- 1. The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ number of stages are required.
Options- A. more
- B. less Discuss
Correct Answer: less
- 2. In velocity compounding of an impulse turbine, the expansion of steam takes place in a nozzle or a set of nozzles from the boiler pressure to condenser pressure.
Options- A. True
- B. False Discuss
Correct Answer: True
- 3. If the critical pressure ratio for steam is 0.546, then the steam is initially
Options- A. wet steam
- B. dry saturated steam
- C. superheated steam
- D. none of these Discuss
Correct Answer: superheated steam
- 4. In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be
Options- A. 160/3 m/s
- B. 320/3 m/s
- C. 640/3 m/s
- D. 640 m/s Discuss
Correct Answer: 640/3 m/s
- 5. In an impulse turbine, steam expands
Options- A. wholly in blades
- B. wholly in nozzle
- C. partly in the nozzle and partly in blades
- D. none of these Discuss
Correct Answer: wholly in nozzle
- 6. A nozzle is said to be a convergent-divergent nozzle, when the cross-section of a nozzle first decreases from its entrance to throat and then increases from its throat to exit.
Options- A. True
- B. False Discuss
Correct Answer: True
- 7. In an ideal impulse turbine, the
Options- A. absolute velocity at the inlet of moving blade is equal to that at the outlet
- B. relative velocity at the inlet of the moving blade is equal to that at the outlet
- C. axial velocity at inlet is equal to that at the outlet
- D. whirl velocity at inlet is equalto that at the outlet Discuss
Correct Answer: relative velocity at the inlet of the moving blade is equal to that at the outlet
- 8. The effect of bleeding is that
Options- 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 Discuss
Correct Answer: all of the above
- 9. A single stage turbine is not used because it requires large reduction gearing due to very high rotational speed.
Options- A. Agree
- B. Disagree Discuss
Correct Answer: Agree
- 10. Which of the following statement is wrong?
Options- 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. Discuss
Correct Answer: 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.
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