Thermal Engineering 28

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Objective Questions and Answer: Thermal Engineering 28

Subject: Thermal Engineering 28

Part 28: Objective questions and answers of Thermal Engineering

 

Q1. In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of

a) Vacuum

b) Atmospheric air

c) Compressed air

d) Oxygen alone

 

Q2. Which of the following fuels can be used in turbojet engines?

a) Liquid hydrogen

b) High speed diesel oil

c) Kerosene

d) Demethylated spirit

 

Q3. Turbo propeller has the following additional feature over the turbojet

a) Propeller

b) Diffuser

c) Intercooler

d) Turbine and combustion chamber

 

Q4. Propulsive efficiency is defined as ratio of

a) Thrust power and fuel energy

b) Engine output and propulsive power

c) Propulsive power and fuel input

d) Thrust power and propulsive power

 

Q5. In jet engines, paraffin is usually used as the fuel because of its

a) High calorific value

b) Ease of atomization

c) Low freezing point

d) (a) and (c) above

 

Q6. A rocket engine for the combustion of its fuel

a) Carries its own oxygen

b) Uses surrounding air

c) Uses compressed atmospheric air

d) Does not require oxygen

 

Q7. A rocket works with maximum overall efficiency when air craft velocity is equal to the

a) Jet velocity

b) Twice the jet velocity

c) Half the jet velocity

d) Average of the jet velocity

 

Q8. Propulsion efficiency of the following order-is obtained in practice

a) 50%

b) 60%

c) 72%

d) 34%

 

Q9. The maximum propulsion efficiency of a turbojet is attained at around following speed –

a) 550 km/hr

b) 1050km/hr

c) 1700 km/hr

d) 2400km /hr

 

Q10. In jet propulsion power unit, the inlet duct of diverging shape is used in order to

a) Collect more air

b) Convert kinetic energy of air into pressure energy

c) Provide robust structure

d) Beautify the shape

 

Q11. In jet engines the products of combustion after passing through the gas turbine are discharged into

a) Atmosphere

b) Back to the compressor

c) Discharge nozzle

d) Vacuum

 

Q12. The air entry velocity m a rocket as compared to aircraft is

a) Same

b) More

c) Less

d) Zero

 

Q13. The weight per horse power ratio for gas. Turbine as compared to I.C. engine and steam turbine is

a) Same

b) Higher

c) Lower

d) Uncomparable

 

Q14. Fighter bombers use following type of engine

a) Turbo-jet

b) Turbo-propeller

c) Rocket

d) Ram-jet

 

Q15. Pick up the wrong statement

a) Pulsojet requires no ambient air for propulsion

b) Ramjet-engine has no turbine

c) Turbine drives compressor in a burbojet

d) Bypass turbo-jet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

 

Q16. Thrust of a jet propulsion power unit can be increased by

a) Burning fuel after gas turbine

b) Injecting water in the compressor

c) Injecting ammonia into the combustion chamber

d) All of the three above

 

Q17. The blades of gas turbine are made of

a) Mild steel

b) Stainless steel

c) Carbon steel

d) High nicked alloy (neimonic).

 

Q18. The following property is most important for material used for gas turbine blade

a) Toughness

b) Fatigue

c) Creep

d) Corrosion resistance

 

Q19. The effective power of gas turbines is increased by adding the following in compressor

a) Ammonia and water vapor

b) Carbon dioxide

c) Nitrogen

d) Hydrogen

 

Q20. High air-fuel ratio is used in gas turbines

a) To increase the output

b) To increase the efficiency

c) To save fuel

d) To reduce the exit temperature

 

Part 28: Objective questions and answers of Thermal Engineering

 

Q1. Answer: c

Q2. Answer: c

Q3. Answer: a

Q4. Answer: d

Q5. Answer: d

Q6. Answer: a

Q7. Answer: c

Q8. Answer: c

Q9. Answer: d

Q10. Answer: b

Q11. Answer: c

Q12. Answer: d

Q13. Answer: c

Q14. Answer: a

Q15. Answer: a

Q16. Answer: d

Q17. Answer: d

Q18. Answer: c

Q19. Answer: a

Q20. Answer: d

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