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Multiple choice question for engineering

Set 1

1. A gas turbine is called as __________
a) Expansion turbine
b) Combustion turbine
c) Compression turbine
d) None of the mentioned

View Answer

Answer: b [Reason:] In gas turbine energy is provided to rotate the turbine by combusting the fuel and hence it is also called as combustion turbine.

2. A combustion chamber in gas turbine is present in between upstream compressor and down stream turbine.
a) True
b) False

View Answer

Answer: a [Reason:] Atmospheric air is compressed in compressor and then fuel is sprinkled on compressed air in combustion chamber and fuel is burnt there. The energy produced in combustion chamber is used to rotate the turbine.

3. In ideal gas turbine isoentropic and isobaric process takes place.
a) True
b) False

View Answer

Answer: a [Reason:] In ideal gas turbine isoentropic compression isobaric compression isoentropic expansion takes place.

4. In actual gas turbine mechanical energy is converted into heat by _________
a) none of the mentioned
b) frictional losses in compressor
c) no mechanical energy is converted into heat energy
d) friction between piston and cylinder

View Answer

Answer: d [Reason:] In combustion chamber friction is present in between piston and cylinder and that is why some of the mechanical energy is converted into heat energy.

5. A typical heat exchanger removing heat from compressor is called as intercooler.
a) True
b) False

View Answer

Answer: a [Reason:] An intercooler is an heat exchanger removing heat from compressor.

6. In IC engines intercooler is used to __________
a) overall efficiency
b) increase volumetric efficiency
c) heat rate
d) none of the mentioned

View Answer

Answer: b [Reason:] Inter cooler reduces unwanted heat from compressor and can increase volumetric efficiency.

7. Knocking of the fuel can be reduced by _________
a) using intercooler
b) decreasing air intake pressure
c) increasing air intake
d) none of the mentioned

View Answer

Answer: a [Reason:] By using intercooler air intake is decreased and hence it reduces knocking of fuel.

8. Compression with intercooler causes ________
a) increase in the compressor work
b) decrease in the compressor work
c) increases the overall efficiency
a) none of the mentioned

View Answer

Answer: b [Reason:] When intercooler is used it uses some of the work produced and reduces the net work done by compressor.

9. Extra cooling can be done by __________
a) decreasing no of fins
b) increasing number of fins
c) spraying mist on inter cooler surface
d) none of the mentioned

View Answer

Answer: c [Reason:] Extra cooling can be done by spraying mist on the surface of intercooler.

10. Using of intercooler and reheating process ________ efficiency.
a) increases
b) decreases
c) does not change
d) none of the mentioned

View Answer

Answer: a [Reason:] When intercooler and reheater is used in gas turbines they increase the efficiency by reducing the wastage of heat.

Set 2

1. Land based gas turbines are classified into _________ types.
a) 3
b) 2
c) 4
d) None of the mentioned

View Answer

Answer: b [Reason:] Land based gas turbines are sub divided into two types.

2. Heavy frame engines are type of _______ based gas turbines.
a) land
b) vertical
c) air
d) none of the mentioned

View Answer

Answer: a [Reason:] Heavy frame engines are type of land based engines.

3. Aero derivative engines are _________ based gas turbines.
a) air
b) vertical
c) land
d) none of the mentioned

View Answer

Answer: c [Reason:] Aero derivative engines are land based gas turbines.

4. Heavy frame engines have _______ pressure ratios.
a) low
b) high
c) medium
d) none of the mentioned

View Answer

Answer: a [Reason:] Heavy frame engines have low pressure ratios. Heavy frame engines work under low pressure ratios.

5. Aero derivative engines have _________ pressure ratios.
a) low
b) high
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] Aero derivative engines have higher pressure ratios. Heavy frame engines work under low pressure ratios.

6. Minimum compression ratio of aero derivative engines are ______
a) 20
b) 40
c) 30
d) None of the mentioned

View Answer

Answer: c [Reason:] Minimum compression ratio of aero derivative engines are 30.

7. Aero derivative engines are very ________ in size.
a) large
b) small
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] Aero derivative engines are very compact. That is why aero derivative engines have high pressure ratios.

8. _______ temperatures in gas turbines gives low efficiency.
a) low
b) high
c) medium
d) none of the mentioned

View Answer

Answer: a [Reason:] High temperature in gas turbines gives high efficiency.

9. Temperatures in gas turbines are about _______
a) 1500 F
b) 1000 F
c) 2300 F
d) none of the mentioned

View Answer

Answer: c [Reason:] Temperatures in gas turbines are about 2300F.

10. When inlet temperature is increased to 2600F then efficiency is about ____________
a) True
b) False

View Answer

Answer: a [Reason:] When inlet temperature is increased to 2600F then efficiency is about 60%.

Set 3

1. In order For turbine to get started air must start flowing ______ to start combustion.
a) outside
b) inside
c) compressing
d) none of the mentioned

View Answer

Answer: b [Reason:] In a gas turbine in order to start a combustion oxygen is required and hence air must start flowing initially.

2. Watt/s is called as a _______
a) joule
b) kilo newton
c) kilo newton/metre
d) none of the mentioned

View Answer

Answer: a [Reason:] Watt/s is called as a joule.

3. When amount of energy required is high the life of gas turbine ________
a) not related
b) decreases
c) increases
d) none of the mentioned

View Answer

Answer: c [Reason:] When amount of energy required is high the life of gas turbine decreases. Because when amount of power required is high its load increases beyond the limit and hence life decreases.

4. In gas turbines _________ output igniters are used at the starting.
a) low
b) high
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] In gas turbines low output igniters are used when the turbine needs to be run continuously.

5. Electronic igniters can be adjusted as per the required ________
a) output
b) power
c) compressing
d) none of the mentioned

View Answer

Answer: a [Reason:] Electronic igniters are used as per the required output.

6. When gas turbine is required to operate continuously then power output is ________
a) increased
b) decreased
c) constant
d) none of the mentioned

View Answer

Answer: b [Reason:] When gas turbine is required to operate continuously the power output is to be reduced as continuous supply of output is needed.

7. When the energy output is __________, igniters life also increases.
a) increased
b) constant
c) decreased
d) none of the mentioned

View Answer

Answer: c [Reason:] When the igniters life is to be increased then the energy output is decreased. When igniters are used to produce high outputs their life is decreased.

8. Gas turbines has _________ pressure high volume fuel pumps.
a) high
b) low
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] Gas turbines has low pressure and high volume fuel pumps. In gas turbines pressure energy in the working fluid is used to increase volume.

9. In some gas turbines cavitations are _______ by using fuel cooled oil cooler.
a) removed
b) increased
d) cavitations are not caused due to oil cooler
d) none of the mentioned

View Answer

Answer: a [Reason:] In fuel cooled oil cooler it heats the fuel to high temperature so that the water droplets present in the fuel gets evaporated and hence prevents the cavitation.

10. In gear type fuel pumps bypass action is due to spill valve.
a) True
b) False

View Answer

Answer: a [Reason:] In gear type fuel pump the bypass action is carried out by spill valve.

Set 4

1. Isoentropic processes in carnot cycle when replaced by constant volume process is called as _______
a) Dual cycle
b) Ericsson cycle
c) Stirling cycle
d) None of the mentioned

View Answer

Answer: c [Reason:] Isoentropic process in carnot cycle when replaced by constant volume process is called as Stirling process.

2. Stirling cycle is reversible.
a) True
b) False

View Answer

Answer: a [Reason:] Since isoentropic process in carnot cycle is replaced by constant volume process, Stirling cycle can be reversible.

3. Stirling cycle can also be called as closed regenerative cycle.
a) True
b) False

View Answer

Answer: a [Reason:] Since Stirling cycle is reversible and is a closed cycle it can also be called as closed regenerative cycle.

4. Stirling cycle can also be categorized as ________
a) internal heat engine
b) external heat engine
c) internal combustion engine
d) none of the mentioned

View Answer

Answer: b [Reason:] When work is supplied to Stirling engine, heating or cooling can be produced as per requirement, So Stirling cycle is categorized as an external heat engine.

5. Processes in Stirling cycle are _______________
a) Compression,Heat addition, Expansion,Heat removal
b) Compression,Heat addition,Expansion
c) Heat addition,Expansion,Heat removal
d) None of the mentioned

View Answer

Answer: a [Reason:] Stirling cycle consists of four processes.They are Compression Heat addition Expansion Heat removal.

6. Compression process that takes place in Stirling engine is _________
a) Constant volume
b) Isothermal
c) Constant pressure
d) None of the mentioned

View Answer

Answer: b [Reason:] In Stirling engine, Isothermal compression takes place.

7. In Stirling engine, pistons are arranged in __________
a) co-linear position
b) linear position
c) parallel position
d) none of the mentioned

View Answer

Answer: a [Reason:] In Stirling engines, co-linear pistons are arranged.

8. In Ericsson cycle, heat addition is done by ___________
a) none of the mentioned
b) isochoric heat addition
c) isothermal heat addition
d) isobaric heat addition

View Answer

Answer: d [Reason:] Heat addition is done by constant pressure process in Ericsson cycle.

9. Ericsson cycle is also known as external combustion engine.
a) True
b) False

View Answer

Answer: a [Reason:] In Ericsson cycle, combustion is done externally and hence it is called as external combustion engine.

10. Separated flow counter – current heat ex-changer is called as __________
a) aeriator
b) regenerator
c) economiser
d) recuperator

View Answer

Answer: d [Reason:] Recuperator can be referred as separated flow counter – current heat ex-changer.

Set 5

1. Torque speed characteristics of _______ shaft gas turbine is same as that of dual shaft gas turbine.
a) single
b) multiple
c) double
d) none of the mentioned

View Answer

Answer: a [Reason:] Torque speed characteristics of single shaft gas turbine is different from the dual shaft gas turbine.

2. In single shaft gas turbine when torque output is 50% engine speed is about _______
a) 50%
b) 80%
c) 90%
d) 100%

View Answer

Answer: b [Reason:] In a single shaft gas turbine when the engine speed is about 80% the torque is about 50%.

3. In a single shaft gas turbine when the engine speed is about 100% the torque output is ______
a) 40%
b) 50%
c) 80%
d) None of the mentioned

View Answer

Answer: d [Reason:] In a single shaft gas turbine when the engine speed is about 100% the torque output is 100%.

4. In a single shaft gas turbine output shaft is connected to a ________ speed compressor.
a) high
b) low
c) medium
d) none of the mentioned

View Answer

Answer: a [Reason:] In a single shaft gas turbine output shaft is connected to a high speed compressor.

5. Stability of the rotation in gas turbine compressor is due to ______ inertia.
a) low
b) high
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] Stability of the rotation in gas turbine compressor is due to high inertia.

6. In a dual shaft gas turbine when the speed is about 60% the torque is increased to _______
a) 100 %
b) 90 %
c) 140 %
d) none of the mentioned

View Answer

Answer: c [Reason:] In a double shaft gas turbine when the speed is about 60% the torque is increased to 140%. These values are found from torque and speed curve.

7. In dual shaft gas turbine when the engine speed is 40% the engine torque is reduced to _________
a) 90%
b) 160%
c) 100%
d) none of the mentioned

View Answer

Answer: b [Reason:] In a dual shaft gas turbine when the engine speed is 40% the torque is increased to 160%. These values are found from graph plotted between torque and speed.

8. Engine output is the ratio of __________ and torque.
a) speed
b) displacement
c) input
d) none of the mentioned

View Answer

Answer: a [Reason:] Product of speed and torque is known as engine output.

9. At low speeds the output is __________ in dual shaft gas turbine.
a) low
b) medium
c) high
d) none of the mentioned

View Answer

Answer: c [Reason:] At low speeds the outputs of dual shaft gas turbines are high.

10. In diesel engines engine output increases when engine speed decreases.
a) True
b) False

View Answer

Answer: b [Reason:] In diesel engines engine output decreases with the decrease in the engine speed.