Compressors

31. Efficiency of gas turbine is increased by

1. reheating
2. inter cooling
3. adding a regenerator
4. all of the above
5. none of the above.

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32. Euler’s equation is applicable for

1. centrifugal compressor
2. axial compressor
3. pumps
4. all of the above
5. none of the above.

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33. Fighter bombers use following type of engine

1. turbo-jet
2. turbo-propeller
3. rocket
4. ram-jet
5. pulsojet.

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34. For a compressor, least work will be done if the compression is

1. isentropic
2. isothermal
3. polytropic
4. somewhere in between isentropic and isothermal
5. none of the above.

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35. For a two stage compressor* if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will

1. increase
2. decrease
3. remain unaffected
4. other factors control it
5. unpredictable.

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36. For actual single stage centrifugal compressor, the maximum pressure ratio is of the order of

1. 01:01.2
2. 01:02
3. 01:04
4. 01:10
5. 01:01

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37. For an irreversible gas turbine cycle, the efficiency and work ratio both depend on

1. pressure ratio alone
2. maximum cycle temperature alone
3. minimum cycle temperature alone
4. both pressure ratio and maximum cycle temperature
5. none of the above.

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38. For minimum work in multistage compression, assuming same index of compression in all stages

1. work done in first stage should be more
2. work done in subsequent stages should increase
3. work done in subsequent stages should decrease
4. work done in all stages should be equal
5. work done in any stage is no criterion for minimum work but depends on other factors.

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39. For slow-speed large capacity compressor, following type of valve will be best suited

1. poppet valve
2. mechanical valve of the corliss, sleeve, rotary or semirotary type
3. disc or feather type
4. any of the above
5. none of the above.

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40. For speed above 3000 km/hour, it is more advantageous to use

1. turbo-jet engine
2. ram-jet engine
3. propellers
4. rockets
5. hydraulic jet propulsion.

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