Steam Nozzles and Turbines problems
- 1. The velocity of whirl at outlet for an axial discharge turbine is
Options- A. minimum
- B. maximum
- C. zero Discuss
Correct Answer: zero
- 2. In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade.
Options- A. equal to
- B. less than
- C. greater than Discuss
Correct Answer: equal to
- 3. The friction present between the steam and the nozzle surfaces reduces the heat drop by
Options- A. 10 to 15 percent
- B. 15 to 25 percent
- C. 25 to 40 percent
- D. 40 to 60 percent Discuss
Correct Answer: 10 to 15 percent
- 4. In a reaction turbine when the degree of reaction is zero, then there is
Options- A. no heat drop in moving blades
- B. no heat drop in fixed blades
- C. maximum heat drop in moving blades
- D. maximum heat drop in fixed blades Discuss
Correct Answer: no heat drop in moving blades
- 5. Degree of reaction is defined as the ratio of
Options- A. heat drop in fixed blades to the heat drop in moving blades
- B. heat drop in moving blades to the heat drop in fixed blades
- C. heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades
- D. heat drop in fixed blades plus heat drop in moving blades to the heat drop in moving blades Discuss
Correct Answer: heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades
- 6. The maximum efficiency of a De-Laval turbine is (where ? = Nozzle angle)
Options- A. sin2 ?
- B. cos2 ?
- C. tan2 ?
- D. cot2 ? Discuss
Correct Answer: cos2 ?
- 7. A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as
Options- A. back pressure turbine
- B. pass out turbine
- C. low pressure turbine
- D. impulse turbine Discuss
Correct Answer: pass out turbine
- 8. The critical pressure ratio is given by (where p1 = Initial pressure of steam, and p2 = Pressure of steam at throat or critical pressure)
Options- A. p1 p2
- B. p1/p2
- C. p2/p1
- D. p1 + p2 Discuss
Correct Answer: p2/p1
- 9. The effect of friction in the nozzle __________ dryness fraction of steam.
Options- A. has no effect on
- B. decreases
- C. increases Discuss
Correct Answer: increases
- 10. In a reaction turbine, when steam flows through the moving blades,
Options- A. pressure increases while velocity decreases
- B. pressure decreases while velocity increases
- C. pressure and velocity both decreases
- D. pressure and velocity both increases Discuss
Correct Answer: pressure and velocity both decreases
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