McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 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 | |
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