Compressors, Gas Dynamics and Gas Turbines problems
- 1. The reason for volumetric efficiency of reciprocating compressor being less than 100 percent is
Options- A. pressure drop across the valves
- B. superheating in compressor
- C. clearance volume and leakages
- D. all of these Discuss
Correct Answer: all of these
- 2. A 3 m3/min compressor means that it
Options- A. compresses 3 m3/min of standard air
- B. compresses 3 m3/ min of free air
- C. delivers 3 m3/ min of compressed air
- D. delivers 3 m3/ min of compressed air at delivery pressure Discuss
Correct Answer: compresses 3 m3/ min of free air
- 3. Slip factor in a centrifugal compressor indicates the amount of air leaked from the storage vessel.
Options- A. Yes
- B. No Discuss
Correct Answer: No
- 4. The compression ratio for the compressor is always __________ unity.
Options- A. equal to
- B. less than
- C. more than Discuss
Correct Answer: more than
- 5. The thrust of a jet propulsion power unit can be increased by
Options- A. injecting water into the compressor
- B. burning fuel after gas turbine
- C. injecting ammonia into the combustion chamber
- D. all of the above Discuss
Correct Answer: all of the above
- 6. With the decrease in compression ratio, the volumetric efficiency
Options- A. does not change
- B. increases
- C. decreases Discuss
Correct Answer: increases
- 7. The overall isothermal efficiency of the compressor is defined as the ratio of
Options- A. work required to compress the air isothermally to the actual work required to compress the air for the same pressure ratio
- B. isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor
- C. volume of free air delivery per stroke to the swept volume of the piston
- D. isentropic power to the power required to drive the compressor Discuss
Correct Answer: isothermal power to the shaft power or B.P. of the motor or engine required to drive the compressor
- 8. In a single stage, single acting reciprocating air compressor, without clearance volume, the workdone is minimum during
Options- A. isothermal compression
- B. isentropic compression
- C. polytropic compression
- D. none of these Discuss
Correct Answer: isothermal compression
- 9. The volumetric efficiency of the compressor is defined as the ratio of volume of free air delivery per stroke to the swept volume of the piston.
Options- A. Yes
- B. No Discuss
Correct Answer: Yes
- 10. The gas in cooling chamber of a closed cycle gas turbine is cooled at
Options- A. constant volume
- B. constant temperature
- C. constant pressure
- D. none of these Discuss
Correct Answer: constant pressure
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