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Multiple choice question for engineering

Set 1

1. Hydrogen seal rings are used to prevent _______ losses.
a) Pressure
b) Temperature
c) Volume
d) None of the mentioned

View Answer

Answer: a [Reason:] Hydrogen seal rings are used to prevent pressure losses. These rings seal the cylinders so that no pressure and temperature loss takes place.

2. _________ oil flow can be controlled by using hydrogen rings.
a) Low
b) Excessive
c) Incomplete
d) None of the mentioned

View Answer

Answer: b [Reason:] Hydrogen rings control excessive oil flow.Excessive oil flow consumes more heat and increases the heat loss.

3. Hydrogen rings are used to control _______ consumption in gas turbine.
a) Fuel
b) Oxygen
c) Hydrogen
d) None of the mentioned

View Answer

Answer: c [Reason:] Hydrogen rings are used to control hydrogen consumption in gas turbine. Hydrogen is used as coolant in gas turbine, Excessive usage of coolant leads to low efficiency.

4. When hydrogen consumption is __________ its efficiency is decreased in turbo generators.
a) increased
b) decreased
c) constant
d) none of the mentioned

View Answer

Answer: a [Reason:] Hydrogen consumption is inversely proportional to efficiency in turbo generators. As hydrogen is used as the coolant and when more amount of coolant is used most heat is lost and hence efficiency is decreased.

5. _________ is used as coolant in turbo generators.
a) Oxygen
b) Hydrogen
c) Fuel
d) None of the mentioned

View Answer

Answer: b [Reason:] Hydrogen is used as coolant in turbo generators. Compared to the other coolants available for gas turbines hydrogen is much cheaper.

6. Hydrogen is combustible below _______% purity limit.
a) 74
b) 50
c) 100
d) None of the mentioned

View Answer

Answer: a [Reason:] Hydrogen is combustible below 74% purity limit.

7. Hydrogen rings are made at _____ degree segments.
a) 360
b) 90
c) 180
d) None of the mentioned

View Answer

Answer: c [Reason:] Hydrogen rings are made at 180 degree segments. The total ring circumference must be 360 degree comprising two parts ( i.e Hydrogen rings) each of 180 degree.

8. Hydrogen rings are of two parts upper case and lower case.
a) True
b) False

View Answer

Answer: a [Reason:] Hydrogen rings are of two parts upper case and lower case.

9. Hydrogen is used because of its ______ specific heat.
a) high
b) low
c) specific is not the factor considered while selecting
d) none of the mentioned

View Answer

Answer: b [Reason:] Hydrogen is used because of its low specific heat.

10. For hydrogen to use as coolant its purity must be more than _______
a) 74%
b) 50%
c) 100%
d) None of the mentioned

View Answer

Answer: a [Reason:] For hydrogen to use as coolant its purity must be more than 74%. Below 74% hydrogen is more combustible in nature.

Set 2

1. Turbojet is a combination of gas turbine with a propeller engine.
a) True
b) False

View Answer

Answer: a [Reason:] Turbojet is an air breathing jet engine which was used in aeroplane. Both gas turbine and propeller together is a turbojet.

2. A compressor in the gas turbine is driven by the Turbine.
a) True
b) False

View Answer

Answer: a [Reason:] In a gas turbine both the turbine and compressor are connected to each other where turbine itself drives the compressor eventually.

3. What is bypass ratio in Turbofan ?
a) None of the mentioned
b) (Mass of the air passing through the engine)/(Mass of the air bypassing the engine)
c) (Air entering the engine)/(Air leaving the engine)
d) (Mass of the air bypassing the engine)/(Mass of the air passing through the engine)

View Answer

Answer: d [Reason:] The term bypass ratio is used in turbofan.In turbofan some of the air enters the engine bypass and rotates the fan while the remaining air rotates the turbine where these two fan and turbine provides the drag force required.Bypass ratio is the ratio of air bypassing the engine to the ratio of air passing through the engine.

4. Turbojet emits ______ engine noise when compared to Turbofan.
a) more
b) less
c) equal
d) none

View Answer

Answer: a [Reason:] Engine’s noise is directly proportional to the air coming from the engine exhaust.In turbojet more air comes from the engine exhaust which is the reason for more noise.

5. Turboprop engines are used in ________ aircrafts.
a) medium
b) large
c) small
d) none

View Answer

Answer: c [Reason:] As the air leaving the engine in turboprop is not sufficient to produce required thrust, turboprop engines are used in conditions where less rpms are required.

6. In turboprop engines ____ torque ____ rpm produced from the engine is converted into high rpm low torque.
a) high, low
b) low, high
c) high, high
d) none

View Answer

Answer: b [Reason:] Turboprop engines generally have low torque and high rpms. In such conditions a reduction gear is used to convert it into low rpm and high torque so that sufficient drag force can be provided.

7. When turboprop and turbofan operate at same speeds, turboprop consumes ________ fuel.
a) more
b) less
c) equal
d) none

View Answer

Answer: a [Reason:] Turbofan produces high rpm, low torque but reduction gear is used to convert it into less rpm and high torque to provide required drag force, but turbo fan operates at high rpms, So for turboprop to operate at same speed as of turbofan they require more fuel when compared to turbofan.

8. In turboprop exhaust fan produces ___________
a) more than 25% of the total thrust
b) more than 40% of the total thrust
c) less than 25% of the total thrust
d) less than 10% of the total thrust

View Answer

Answer: d [Reason:] Due to additional expansion in the turbine system, Energy in the thrust jet is lesser than 10% of the total energy produced by turboprop.

9. Turboprops are not generally operated in high speeds because of ________
a) while speed of the engine increases it looses it efficiency
b) turboprops are not able to produce high speeds
c) turboprops produce high torques
d) none of the mentioned

View Answer

Answer: a [Reason:] Turboprops cannot be operated at high speeds. Turboprops are operated in between 0.6 and 0.7. When they are operated more than the mentioned speeds they loose their efficiency.

10. A closed cycle gas turbine follows ________
a) Dual Cycle
b) Brayton Cycle
c) Stirling cycle
d) Carnot cycle

View Answer

Answer: b [Reason:] Closed cycle Gas turbines follow Brayton cycle.

Set 3

1. Multi spool gas turbines are operated at high pressure and high idle rpm
a) True
b) False

View Answer

Answer: a [Reason:] Multi spool gas turbine has high pressure spool operating at high idle rpm.

2. Based on type of flow arrangements gas turbines are classified into _____________
a) None of the mentioned
b) Impulse-reaction gas turbine
c) Open cycle gas turbine
d) Axial flow gas turbine

View Answer

Answer: d [Reason:] Based on type of flow, Gas turbines are divided into two types. They are Axial flow gas turbines, radial flow gas turbines.

3. Identify the types of Gas turbines ___________
a) Turbo jet
b) Turboprop
c) Turbo fan
d) All of the mentioned

View Answer

Answer: d [Reason:] Gas turbines are further classified into Turbojet, Turboprop ,Turbo fan, After burning Turbo jet.

4. Gas Turbine Engines when compared to Reciprocating engines have ________
a) high power to weight ratio
b) low power to weight ratio
c) produce low power
d) none of the mentioned

View Answer

Answer: a [Reason:] High power to weight ratio is the basic reason behind using Gas turbines in Air crafts thereby replacing reciprocating engines.

5. For producing Same power ____________
a) reciprocating engines will be smaller when compared to Gas turbine engines
b) gas turbine engines are smaller when compared to reciprocating engine counter parts
c) reciprocating engines are complex
d) none of the mentioned

View Answer

Answer: b [Reason:] As for gas turbine Engine power to weight ratio is less when compared to reciprocating engine.

6. Most preferable Gas turbines are required to be used in _____________
a) fluctuating loads
b) constant loads
c) idling conditions
d) none of the mentioned

View Answer

Answer: b [Reason:] Gas turbines are preferred to be used in constant load conditions as Fluctuating loads requires fluctuating power for which fuel is more consumed.

7. Gas turbines work on ________
a) Otto cycle
b) Dual cycle
c) Brayton cycle
d) Diesel cycle

View Answer

Answer: c [Reason:] Gas turbines works on brayton cycle.

8. Amount of fuel energy used by compressor is __________
a) half the total energy
b) two third of the total energy
c) one third of the total energy
d) none of the mentioned

View Answer

Answer: b [Reason:] Two thirds of the total energy produced from combustion of fuel is used by compressor.

9. Gas turbine performance majorly depends on __________
a) compressor efficiency
b) calorific value of fuel used
c) nozzle efficiency
d) none of the mentioned

View Answer

Answer: a [Reason:] As two thirds of the total energy produced from combustion is used by compressor, compressor efficiency plays a major role in determining Gas turbine performance.

10. Some of the types of combustors available are
a) annular
b) can Annular
c) silo
d) all of the mentioned

View Answer

Answer: d [Reason:] Types of Combustor are Annular Can Annular Silo.

Set 4

1. Gas and Steam turbine combined power plant produces more electricity than traditional power plants by how much percent ?
a) 25
b) 40
c) 50
d) The given statement was false

View Answer

Answer: c [Reason:] When steam and gas turbines are jointly used in power plants and the power produced by gas and steam turbines is used in producing electricity.

2. Marine compound power plants are also the combined gas and steam power plants.
a) True
b) False

View Answer

Answer: a [Reason:] Combined gas and steam power plants is the name given to marine power plants.

3. Maximum supplementary firing means _________
a) minimum fuel that can be fired
b) maximum fuel that can fired with the oxygen available in turbine
c) maximum fuel that can be fired in given time
d) none of the mentioned

View Answer

Answer: b [Reason:] Maximum supplementary firing means maximum fuel that can be fired with the oxygen available.

4. Due to the limits, upper efficiency of steam turbines is fixed to
a) 10-15%
b) 25-45%
c) 20-40%
d) 35-45%

View Answer

Answer: d [Reason:] In steam and gas turbine combined power plants, steam turbines water is used as working medium. High pressure and high temperatures are required for these high pressures which in turn requires high strengths so expensive alloys like nickel and cobalt are used. These limit the upper efficiency to 35-45%.

5. How many sections do waste heat recovery boiler have in steam generators ?
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: c [Reason:] In steam generators waste heat recovery boilers have 3 sections. They are Economiser Evaporator Superheater.

6. Turbines that are run by exhaust gases are called _______
a) power recovery turbines
b) stepped turbines
c) turbo compounded engine
d) none of the mentioned

View Answer

Answer: a [Reason:] Turbines that are run by exhaust gases are called power recovery turbines.

7. Combination of two or more thermodynamic processes gives
a) decrease in efficiency
b) increase in efficiency
c) increases the temperature at exhaust
d) none of the mentioned

View Answer

Answer: b [Reason:] When two or more thermodynamic cycles work together their overall combined efficiency increases by 50-60%.

8. By using combined cycle steam and gas power plant _________
a) specific fuel consumption can be decreased
b) efficiency increased
c) both the answers mentioned are correct
d) none of the mentioned

View Answer

Answer: c [Reason:] If specific fuel consumption is decreased it indirectly increases the efficiency.

9. What are turbo-compound engines ?
a) Turbines run at exhausts of Otto and diesel cycles
b) Combination of turbofan and turbojet engines
c) Combination of turboprop and turbofan engines
d) None of the mentioned

View Answer

Answer: a [Reason:] Turbo compound engines are used in air-crafts where turbines run at exhausts of Otto and diesel cycles.

Set 5

1. Steam turbines work on __________
a) Otto cycle
b) Dual cycle
c) Rankine cycle
d) None of the mentioned

View Answer

Answer: c [Reason:] Otto cycle petrol is used as fuel, Rankine cycle is the process followed in steam turbines.

2. Gas turbines work on ___________
a) Rankine cycle
b) Diesel cycle
c) Brayton cycle
d) None of the mentioned

View Answer

Answer: c [Reason:] Rankine cycle is used in steam turbines. Brayton cycle is followed in gas turbines.

3. Generally water is used as working fluid in rankine cycle.
a) True
b) False

View Answer

Answer: a [Reason:] Rankine cycle is followed in steam turbines. In steam turbines generally water is used as working fluids.

4. Ideal Brayton cycle consists of ________
a) Isoentropic process and Isobaric process
b) Adiabatic process and Isobaric process
c) Adiabatic process
d) None of the mentioned

View Answer

Answer: a [Reason:] Ideal brayton cycle works on isoentropic process and isobaric process.

5. Actual Brayton cycle works on _________
a) Isoentropic process and Isobaric process
b) Adiabatic process and Isobaric process
c) Isoentropic process
d) None of the mentioned

View Answer

Answer: b [Reason:] Actual brayton cycle works on Adiabatic process and Isobaric process slight deviations from actual brayton cycle.

6. Brayton cycle is also known as__________
a) Joule cycle
b) Regenerative cycle
c) Carnot cycle
d) None of the mentioned.

View Answer

Answer: a [Reason:] Regenerative cycle is a closed loop usage of working fluid in rankine cycle . Brayton cycle is also called as joule cycle.

7. Brayton cycle is also called as Ericsson cycle.
a) True
b) False

View Answer

Answer: a [Reason:] Brayton cycle is also called as ericsson cycle.

8. Brayton cycles are further divided into ______ types.
a) 2
b) 3
c) 4
d) None of the mentioned

View Answer

Answer: a [Reason:] Brayton cycle is further divided into two types. They are open cycle and closed cycle.

9. Internal combustion chamber is used in _______ Brayton cycle.
a) open
b) closed
c) depends
d) none

View Answer

Answer: a [Reason:] Internal combustion chambers are present in open cycles to heat the working fluid.

10. Heat exchanger is used in closed Brayton cycle.
a) True
b) False

View Answer

Answer: a [Reason:] Heat exchangers are used in closed cycles to raise the temperature of working fluid.

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