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1. |
Normal standard of compression for rotary compressor is |
A. | polytropic compression |
B. | constant pressure compression |
C. | isentropic compression |
D. | adiabatic compression |
Answer» C. isentropic compression |
2. |
The continuity equation in compressible fluids is derived on the basis of |
A. | conservation of velocity head |
B. | conservation of mass |
C. | conservation of energy |
D. | conservation of momentum |
Answer» B. conservation of mass |
3. |
Gas turbine used in aircraft is of |
A. | closed cycle type with reheating and regeneration and intercooling |
B. | closed cycle type with reheating |
C. | open cycle type with reheating, regeneration and intercooling |
D. | open cycle type |
Answer» D. open cycle type |
4. |
With increase in pressure ratio, thermal efficiency of a simple gas turbine plant with fixed turbine inlet temperature |
A. | increases |
B. | decreases |
C. | first increases and then decreases |
D. | none of the above |
Answer» C. first increases and then decreases |
5. |
The ratio of actual velocity to the local velocity of sound is called |
A. | Velocity factor |
B. | Speed ratio |
C. | Mach number |
D. | Velicity ratio |
Answer» C. Mach number |
6. |
Actual gas turbine cycle is different from ideal cycle because |
A. | of internal irreversibility of the process due to friction, turbulence, etc. |
B. | of variation of specific heats with temperature |
C. | of losses due to incomplete combustion |
D. | all of the above |
Answer» D. all of the above |
7. |
Gas turbines are taken to |
A. | the gasoline and diesel engines in its working medium |
B. | the petrol and diesel engines in its internal combustion |
C. | the steam turbine in its aspect of steady flow of the working medium |
D. | All of the above |
Answer» D. All of the above |
8. |
Which component of a gas turbine consumes maximum power? |
A. | Combustion chamber |
B. | Regenerator |
C. | Starter |
D. | Compressor |
Answer» D. Compressor |
9. |
Critical pressure for steam is |
A. | 185.85 kg/cm2 |
B. | 245.55 kg/cm2 |
C. | 225.65 kg/cm2 |
D. | 212.55 kg/cm2 |
Answer» C. 225.65 kg/cm2 |
10. |
Which of the following preferred for supercharging of internal combustion engines? |
A. | Roots blower |
B. | Reciprocating compressor |
C. | Sliding vane type compressor |
D. | Axial flow compressor |
Answer» A. Roots blower |
11. |
Which gas turbine has lest weight per bhp developed? |
A. | Simple open cycle gas turbine |
B. | Open cycle gas turbine with intercooling, reheating and regeneration |
C. | Closed cycle gas turbine |
D. | Open cycle gas turbine with intercooling and reheating |
Answer» A. Simple open cycle gas turbine |
12. |
In which of the following plant inferior quality fuel can be used? |
A. | Open cycle gas turbine with regeneration |
B. | Open cycle gas turbine with intercooling |
C. | Closed cycle gas turbine |
D. | Open cycle gas turbine with reheating and regeneration |
Answer» C. Closed cycle gas turbine |
13. |
Which of the following loss in steam turbines is negligible? |
A. | Residual velocity loss |
B. | Radiation loss |
C. | Leakage loss |
D. | Mechanical friction loss |
Answer» B. Radiation loss |
14. |
Most serious energy loss in reaction steam turbine |
A. | Steam leakage between diaphragm and shaft |
B. | Impact loss as steam enters moving blades |
C. | Frictional resistance between steam and nozzle side |
D. | Leakage over blade ends through radia clearance passages |
Answer» D. Leakage over blade ends through radia clearance passages |
15. |
An axial flow compressor is suitable for |
A. | low volume flow rates with high pressure rise |
B. | high volume flow rates with a small pressure rise |
C. | low volume flow rates with low pressure rise |
D. | high volume flow rates with high pressure rise |
Answer» B. high volume flow rates with a small pressure rise |
16. |
For a jet prepulsion unit, ideally the compressor work and turbine work are |
A. | unequal |
B. | equal |
C. | not related to each other |
D. | none of the above |
Answer» B. equal |
17. |
Stalling of the blades of axial flow compressor is |
A. | an unsteady periodic and reversal of flow |
B. | the fixed mass flow rate regardless of pressure ratio |
C. | the reduction in lift force at higher angle of incidence |
D. | none of the above |
Answer» C. the reduction in lift force at higher angle of incidence |
18. |
In a two stage gas turbine plant reheating after first stage |
A. | increases thermal efficiency |
B. | decreases thermal efficiency |
C. | doesoes not affect thermal efficiency |
D. | none of the above |
Answer» B. decreases thermal efficiency |
19. |
In a nozzle if back pressure is equal to inlet pressure |
A. | maximum flow occurs |
B. | no flow occurs |
C. | flow is subsonic in diverging section |
D. | flow is supersonic in converging as well as supersonic sections |
Answer» B. no flow occurs |
20. |
The source of power for driving a turbocharger is |
A. | chemical energy of exhaust gases |
B. | air motor |
C. | kinetic energy of exhaust gases from the engine |
D. | electric motor |
Answer» C. kinetic energy of exhaust gases from the engine |
21. |
The diverging portion of the nozzle acts as a diffuser for |
A. | the subsonic flow |
B. | the supersonic flow |
C. | both the subsonic as well as supersonic flow |
D. | none of the above |
Answer» A. the subsonic flow |
22. |
Efficiency of gas turbine is increased by |
A. | Reheating |
B. | Intercooling |
C. | Adding a regenerator |
D. | All of the above |
Answer» D. All of the above |
23. |
Curtis turbine is |
A. | a velocity pressure compounded turbine |
B. | a velocity compounded turbine |
C. | in impulse turbine |
D. | a pressure compounded turbine |
Answer» A. a velocity pressure compounded turbine |
24. |
Which of the following is a pressure compounded turbine? |
A. | Parson's turbine |
B. | Curtis turbine |
C. | Rateau turbine |
D. | All of the above |
Answer» C. Rateau turbine |
25. |
The work ratio of closed cycle gas turbine plant with fixed top temperature of the cycle and fixed pressure ratio rp |
A. | increases with increase in an inlet temperature to compressor |
B. | increases with decrease in an inlet temperature to compresor |
C. | remain same irrespective of inlet temperature to compressor |
D. | none of the above |
Answer» B. increases with decrease in an inlet temperature to compresor |
26. |
In an axial flow compressor, the pressure rise occurs in |
A. | fixed blades only |
B. | Moving blades only |
C. | Both fixed and moving blades |
D. | none of the above |
Answer» C. Both fixed and moving blades |
27. |
Surging is |
A. | an unsteady, periodic and reversal of flow in the compressor |
B. | the fixed mass flow rate regardless of pressure ratio |
C. | the reduction in lift force at higher angles of incidence |
D. | none of the above |
Answer» A. an unsteady, periodic and reversal of flow in the compressor |
28. |
A regenerator can be used on |
A. | open cycle gas turbines only |
B. | closed cycle gas turbines only |
C. | both open as well as closed cycle gas turbines |
D. | none of the above |
Answer» C. both open as well as closed cycle gas turbines |
29. |
Maximum delivery pressure in a rotary air compressor is of the order of |
A. | 10 KSC |
B. | 16 KSC |
C. | 6 KSC |
D. | 25 KSC |
Answer» B. 16 KSC |
30. |
An axial flow compressor has |
A. | smaller blades at gas entry and larger blades at exit |
B. | identical dlades at exit as well as entry |
C. | larger blades at gas entry and smaller blades at exit |
D. | size of blades remains same only angles changes |
Answer» C. larger blades at gas entry and smaller blades at exit |
31. |
In a gas turbine cycle regenerator is used to |
A. | heat fuel supplied to combustion chamber |
B. | heat air supplied to combustion chamber |
C. | heat the gases coming out of combustion chamber |
D. | heat exhaust gases released from low pressure turbine |
Answer» B. heat air supplied to combustion chamber |
32. |
In a nozzle, once the critical conditions are achieved at the throat, than which of the following remains constant |
A. | Density of fluid |
B. | Velocity of fluid |
C. | Flow rate |
D. | All of the above |
Answer» D. All of the above |
33. |
The range of compression ratio in a gas turbine is |
A. | 3 to 6 |
B. | 5 to 8 |
C. | 12 to 22 |
D. | 8 to 12 |
Answer» B. 5 to 8 |
34. |
In a hot wire anemometer the rate of heat loss from sensing element is a function of |
A. | pressure |
B. | mass rate of flow |
C. | velocity of flow |
D. | none of the above |
Answer» C. velocity of flow |
35. |
When working substance is released through nozzles, the direction of reaction will be |
A. | clockwise |
B. | counter clockwise |
C. | either of (A) and (B) above |
D. | direction depends on other design features |
Answer» B. counter clockwise |
36. |
Though there are no cyclic variations even then rotary compressors need precise balancing because |
A. | It is bulky in size |
B. | it is driven by an electric motor |
C. | cooling arrangement does not exist |
D. | operating speeds are too high |
Answer» D. operating speeds are too high |
37. |
In a velocity compounded steam turbine, as steam moves along moving and guide blades |
A. | both pressure and velocity gradually decrease |
B. | Both pressure and velocity gradually increase. |
C. | pressure gradually increases and velocity is low |
D. | pressure is low and velocity gradually decreases |
Answer» D. pressure is low and velocity gradually decreases |
38. |
Generally, steam turbines in power stations operate at |
A. | 3000 rpm |
B. | 375 rpm |
C. | 1000 rpm |
D. | 1500 rpm |
Answer» A. 3000 rpm |
39. |
An ideal fluid for vapour turbine cycle should have |
A. | low critical temperature with high pressure |
B. | high critical temperature with low pressure |
C. | high critical temperature with high pressure |
D. | low critical temperature with low presure |
Answer» B. high critical temperature with low pressure |
40. |
Overall efficiency of a gas turbine is |
A. | less than Diesel cycle efficiency |
B. | more than Otto or Diesel cycle efficiency |
C. | equal to Rankine cycle efficiency |
D. | equal to Carnot cycle efficiency |
Answer» A. less than Diesel cycle efficiency |
41. |
In gas turbines, intercooling results in |
A. | decrease in net output and increase in thermal efficiency |
B. | decrease in net output as well as thermal efficiency |
C. | increase in net output as well as thermal efficiency |
D. | increase in net output but decrease in thermal efficiency |
Answer» C. increase in net output as well as thermal efficiency |
42. |
Maximum delivery pressure in case of rotary compressors is usually restricted to |
A. | 5 atmospheres |
B. | 10 atmospheres |
C. | 2 atmospheres |
D. | 20 atmospheres |
Answer» B. 10 atmospheres |
43. |
For efficient operation of axial flow compressors the blades are made |
A. | aerofoil section |
B. | forward curved |
C. | straight |
D. | slightly curved |
Answer» A. aerofoil section |
44. |
Under standard atmospheric condition, the velocity of air is |
A. | 236 m/s |
B. | 436 m/s |
C. | 336 m/s |
D. | 536 m/s |
Answer» C. 336 m/s |
45. |
A diffuser |
A. | converts thermal energy into kinetic energy |
B. | converts pressure energy into kinetic energy |
C. | converts kinetic energy into thermal energy |
D. | converts potential energy into kinetic energy |
Answer» C. converts kinetic energy into thermal energy |
46. |
Which of the following is a positive displacement rotory compressor? |
A. | Roots blower |
B. | Centrifugal compressor |
C. | Axial flow compressor |
D. | All of the above |
Answer» A. Roots blower |
47. |
In which of the following heat exchanger, heat is extracted from air? |
A. | Regenerator |
B. | Reheater |
C. | Intercooler |
D. | All of the above |
Answer» C. Intercooler |
48. |
The following property is the most important for material used for gas turbine blades |
A. | Fatigue |
B. | Strength against bending |
C. | Strength against direct force |
D. | Group |
Answer» D. Group |
49. |
Which of the following fluid can be used in binary vapour cycle? |
A. | Mercury |
B. | Diphenyl oxide |
C. | Aluminium bromide |
D. | any of the above |
Answer» D. any of the above |
50. |
A control volume has an inlet area of 0.1 m2 and exit area of 0.05 m2. The density is 3.89 kg/m2 and constant. If the inlet velocity is 30 m/s, the force on the control volume will be |
A. | 350 N |
B. | 150 N |
C. | 50 N |
D. | 250 N |
Answer» A. 350 N |
51. |
In a reheating gas turbine cycle, reheating is done |
A. | by gases from turbine exhaust |
B. | by gases from intercooler |
C. | in separate combustion chamber |
D. | any of the above |
Answer» C. in separate combustion chamber |
52. |
The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called |
A. | Blade efficiency |
B. | Diagram efficiency |
C. | slip factor |
D. | Velocity ratio |
Answer» C. slip factor |
53. |
Thermal efficiency of a gas turbine is in the range |
A. | 20 to 30 percent |
B. | 40 to 50 percent |
C. | 50 to 60 percent |
D. | 30 to 40 percent |
Answer» D. 30 to 40 percent |
54. |
A roots blower compresses 0.06 cubic metres of air from 1.0 bar to 1.45 bar per revolution. The compressor efficiency is nearly |
A. | 75% |
B. | 63% |
C. | 87% |
D. | 99% |
Answer» C. 87% |
55. |
Basic closed cycle for gas turbine is |
A. | Carnot cycle |
B. | Rankine cycle |
C. | Brayton cycle |
D. | none of the above |
Answer» C. Brayton cycle |
56. |
The advantage of a gas turbine over a reciprocating engine is |
A. | perfect balancing of rotor |
B. | continuous and uniform power |
C. | usually small working pressures |
D. | all of the above |
Answer» D. all of the above |
57. |
A diffuser is used to |
A. | increase velocity and decrease pressure |
B. | increase velocity as well as pressure |
C. | decrease velocity as well as pressure |
D. | decrease velocity and increase pressure |
Answer» D. decrease velocity and increase pressure |
58. |
Air fuel ratio for a gas turbine is closer to |
A. | 60 ; 1 |
B. | 10 ; 1 |
C. | 15 ; 1 |
D. | 20 ; 1 |
Answer» A. 60 ; 1 |
59. |
Which of the following steam turbine has identical fixed and moving blades? |
A. | Curtis turbine |
B. | Rateau turbine |
C. | Parson's turbine |
D. | none of the above |
Answer» C. Parson's turbine |
60. |
Bleeding in steam turbine refers to |
A. | purposely withdrawn steam for process application |
B. | leakage of steam through bearings |
C. | purposely withdrawn for feed water heating |
D. | leakage of steam through packings |
Answer» C. purposely withdrawn for feed water heating |
61. |
As a result of blade friction, the outlet relative velocity of impulse turbine compared to inlet relative velocity is |
A. | Nearly same |
B. | 2% less |
C. | 10% - 15% less |
D. | 30% less |
Answer» C. 10% - 15% less |
62. |
As there is plenty of time for heat transfer across the walls, the flow in long pipes at low velocities attains |
A. | adiabatic conditions |
B. | isothermal conditions |
C. | polytropic conditions |
D. | isentropic conditions |
Answer» B. isothermal conditions |
63. |
The normal shock wave in compressible flow is analogous to |
A. | hydraulic bore in tidal rivers |
B. | vortex formation in centrifugal pump |
C. | hydraulic jump in channel flow |
D. | surges in open channel |
Answer» C. hydraulic jump in channel flow |
64. |
Greater the difference between jet velocity and aeroplane velocity |
A. | greater the propulsive efficiency |
B. | Lesser the propulsive efficiency |
C. | unaffected is the propulsive efficiency |
D. | None of the above |
Answer» B. Lesser the propulsive efficiency |
65. |
If stage efficiency is S, blade efficiency is B and nozzle efficiency in N, then |
A. | BSN = 1 |
B. | N = B.S |
C. | S = B.N |
D. | B = SN |
Answer» C. S = B.N |
66. |
Choking is |
A. | Variation of mass flow rate in proportion to pressure ratio |
B. | variation of mass flow rate in inverse proportion to pressure ratio |
C. | fixed mass flow rate regardless of pressure ratio |
D. | none of the above |
Answer» C. fixed mass flow rate regardless of pressure ratio |
67. |
The advantage of closed cycle gas turbine over open cycle gas turbine is |
A. | no contamination of working substance with combustion gases |
B. | inferior quality fuel can be used |
C. | low maintenance costs |
D. | All of the above |
Answer» D. All of the above |
68. |
Brayton cycle cannot be used in reciprocating engines even for same compression ratio and work output because |
A. | Large volume of low pressure gas cannot be efficiently handled in reciprocating engines |
B. | Brayton cycle is less efficient |
C. | Otto cycle is more efficient |
D. | Brayton cycle is for slow speed engines only |
Answer» A. Large volume of low pressure gas cannot be efficiently handled in reciprocating engines |
69. |
Working medium for closed cycle gas turbine should have |
A. | high molecular weight |
B. | low specific volume |
C. | higher adiabatic index |
D. | lower specific speed |
Answer» C. higher adiabatic index |
70. |
Thermal efficiency of a gas turbine cycle can be improved by |
A. | reheating between expansion stage |
B. | intercooling between compression stges |
C. | regeneration |
D. | any of the above |
Answer» D. any of the above |
71. |
Thermal efficiency of closed cycle gas turbine plant increases by |
A. | reheating |
B. | intercooling |
C. | regenerator |
D. | All of the above |
Answer» D. All of the above |
72. |
For gas turbine, compressors used are |
A. | Centrifugal type |
B. | Lobe type |
C. | Axial flow type |
D. | Reciprocating type |
Answer» C. Axial flow type |
73. |
Which of the following is the least efficient method of governing steam turbines? |
A. | Combined throttle and nozzle governing |
B. | Throttle governing |
C. | Nozzle control governing |
D. | Bypass governing |
Answer» B. Throttle governing |
74. |
The effect of blade friction in a steam turbine is to |
A. | increase the specific output |
B. | reduce work done |
C. | reheat the steam |
D. | reduce exhaust pressure |
Answer» B. reduce work done |
75. |
In rotory compressors, the ratio of isentropic work to Eulers work is known as |
A. | degree of reaction |
B. | slip factor |
C. | work factor |
D. | pressure coefficient |
Answer» D. pressure coefficient |
76. |
Ljungstrom steam turbine is a |
A. | radial flow turbine |
B. | axial flow turbine |
C. | mixed flow turbine |
D. | any of the above |
Answer» A. radial flow turbine |
77. |
A constant volume combustion gas turbine operates on |
A. | Joule cycle |
B. | Ericsson cycle |
C. | Brayton cycle |
D. | Atkinson cycle |
Answer» D. Atkinson cycle |
78. |
All of the following are positive displacement compressors EXCEPT |
A. | Vane blower |
B. | Roots blower |
C. | Screw compressor |
D. | Axial flow compressor |
Answer» D. Axial flow compressor |
79. |
De Laval turbine is used for applications requiring |
A. | High power, low speed |
B. | Low power, high speed |
C. | High power, high speed |
D. | Low power, low speed |
Answer» B. Low power, high speed |
80. |
Which type of rotary compressor is used in oil fired furnaces? |
A. | Sliding vane type blower |
B. | Axial flow compressor |
C. | Screw compressor |
D. | Centrifugal blower |
Answer» D. Centrifugal blower |
81. |
In a two stage gas turbine plant, reheating after first stage |
A. | increases work ratio |
B. | decreases work ratio |
C. | does not affect work ratio |
D. | none of the above |
Answer» A. increases work ratio |
82. |
The efficiency of a simple open cycle gas turbine depends upon |
A. | pressure ratio |
B. | compressor efficiency |
C. | turbine inlet temperature |
D. | All of the above |
Answer» D. All of the above |
83. |
In a nozzle under choked flow conditions pressure waves travel, in the divergent portion, at |
A. | subsonic to supersonic speed |
B. | supersonic speed |
C. | sonic speed |
D. | subsonic speed |
Answer» C. sonic speed |
84. |
Which of the following is a displacement compressors? |
A. | Reciprocating air compressor |
B. | Centrifugal blower |
C. | Axial flow compressors |
D. | Vane blower |
Answer» D. Vane blower |
85. |
With ideal regencrative heat exchanger, the thermal efficiency of gas turbine cycle is |
A. | equal to work ratio |
B. | is less than work ratio |
C. | is more than work ratio |
D. | none of the above |
Answer» A. equal to work ratio |
86. |
In a modern steam turbine, the steam rte is nearly |
A. | 1 kg/kWhr |
B. | 8 kg/kWhr |
C. | 4 kg/kWhr |
D. | 2 kg/kWhr |
Answer» C. 4 kg/kWhr |
87. |
In air compressor performance curve a surge line represents |
A. | limits of compressor discharge |
B. | limit of compressor efficiency |
C. | lower critical speed of shaft |
D. | limit of stable operation |
Answer» D. limit of stable operation |
88. |
In rotary compressors, slip factor is the ratio of |
A. | stagnation pressure to static pressure |
B. | isentropic work done to actual work |
C. | outlet whirl velocity to the blade velocity |
D. | none of the above |
Answer» C. outlet whirl velocity to the blade velocity |
89. |
In a gas turbine combined cycle plant, a waste heat boiler is used to |
A. | heat air from intercooler |
B. | gases from regenerator |
C. | recover heat form exhaust gases |
D. | none of the above |
Answer» C. recover heat form exhaust gases |
90. |
The flow on two sides of a normal shock wave is |
A. | supersonic on one side and subsonic on the other side |
B. | subsonic |
C. | supersonic |
D. | sonic |
Answer» A. supersonic on one side and subsonic on the other side |
91. |
Which of the following rotary compressor has two shafts? |
A. | Sliding vane compressor |
B. | Centrifugal compressor |
C. | Lobe type compressor |
D. | Axial flow compressor |
Answer» C. Lobe type compressor |
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