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Multiple choice question for engineering

Set 1

1. Pressure ratios below 20 are used in _____________ engines.
a) steam turbine
b) aero derivative engines
c) heavy frame engines
d) none of the mentioned

View Answer

Answer: c [Reason:] Lower pressure ratios are maintained in heavy frame engines.

2. Heavy frame engines are physically _______
a) medium
b) large
c) small
d) none of the mentioned

View Answer

Answer: b [Reason:] Heavy frame engines are physically large.

3. Aeroderivative engines have pressure ratios ___________
a) greater than 30
b) lesser than 30 and greater than 20
c) greater than 50
d) none of the mentioned

View Answer

Answer: a [Reason:] Higher pressure ratios of greater than 30 are used in aeroderivative engines.

4. Aeroderivative engines are used where ____________ power units are required.
a) larger
b) smaller
c) optimum
d) none of the mentioned

View Answer

Answer: b [Reason:] Aeroderivative engines are used where smaller power units are required.

5. Aeroderivative engines are larger.
a) True
b) False

View Answer

Answer: b [Reason:] Aeroderivative engines are compact and smaller in size.

6. Aeroderivative engines release higher emissions.
a) True
b) False

View Answer

Answer: a [Reason:] Aeroderivative engines are smaller and produce high output as a result of which they release higher emissions.

7. Gas turbines operate at pressures ________ than critical pressure ratio.
a) higher
b) lesser
c) does not depend on pressure ratio
d) none of the mentioned

View Answer

Answer: b [Reason:] Gas turbines operate at pressures less than critical pressure ratio.

8. Critical pressure ratio is ratios of pressures at _________ discharge.
a) minimum
b) none of the mentioned
c) optimum
d) maximum

View Answer

Answer: d [Reason:] Critical pressure ratio is the ratios of pressure at maximum discharge.

9. Ratio of critical pressure to inlet pressure in known as ___________
a) none of the mentioned
b) pressure ratio
c) critical pressure ratio
d) isoentropic pressure ratio

View Answer

Answer: c [Reason:] Ratio of critical pressure to inlet pressure is called as critical pressure ratio.

10. In De Laval Nozzle critical pressure ratio is given by (2/y+1)^(y/y-1).
a) True
b) False

View Answer

Answer: a [Reason:] Critical pressure ratio of De Laval nozzle is derived theoretically.

Set 2

1. Nozzle is used to control direction or characteristics of flow.
a) True
b) False

View Answer

Answer: a [Reason:] Nozzle is used to control the direction and characteristics of flow.

2. Nozzles are used to control the ___________
a) temperature
b) rate of flow
c) mass flow rate
d) none of the mentioned

View Answer

Answer: b [Reason:] Nozzles are used to control the rate, speed, direction of flow.

3. A nozzle used to send fluid in coherent stream is called as ________
a) jet
b) high velocity nozzle
c) every nozzle sends fluid in coherent stream
d) none of the mentioned

View Answer

Answer: a [Reason:] A nozzle used to send the fluid in coherent stream is called as jet.

4. In fountains the type of nozzle used is _______
a) none of the mentioned
b) turbulent jet
c) high speed nozzle
d) laminar jet

View Answer

Answer: d [Reason:] Laminar jet nozzle is used to convert the fluid in laminar flow.

5. Nozzles used in blast furnaces are called as _______
a) jet
b) hot blast
c) tuyeres
d) none of the mentioned

View Answer

Answer: c [Reason:] Nozzles used in blast furnaces are called tuyeres.

6. If mach number is less than one then its flow is ______________
a) subsonic flow
b) turbulent flow
c) laminar flow
d) none of the mentioned

View Answer

Answer: a [Reason:] If M<1 then it is subsonic flow.

7. Nozzle used in rocket engine is __________
a) convergent nozzle
b) divergent nozzle
c) convergent – Divergent nozzle
d) none of the mentioned

View Answer

Answer : c [Reason:] In rocket air flows from convergent section first and then from divergent section.

8. In rocket engine the flow in the throat of the nozzle is __________
a) subsonic
b) laminar
c) turbulent
d) none of the mentioned

View Answer

Answer: a [Reason:] In the throat of nozzle mach number is less than one which indicates the flow is subsonic.

9. When mach number is greater than one the flow is ________
a) subsonic
b) supersonic
c) laminar
d) none of the mentioned

View Answer

Answer: b [Reason:] When M>1 the flow is supersonic.

10. In rocket engines the amount of expansion in Nozzle determines the __________
a) exit temperature
b) exit pressure
c) exit temperature & pressure
d) none of the mentioned

View Answer

Answer: c [Reason:] When the flow is subsonic, air in nozzle expands isoentropically and hence exit temperature and exit pressure depends on the amount of expansion.

Set 3

1. A turbine having alternate blades and nozzles is called as _______________
a) Impulse turbine
b) Reaction turbine
c) Impulse & Reaction turbine
d) None of the mentioned

View Answer

Answer: a [Reason:] When blades and nozzles are arranged in alternate manner pressure loss can be reduced and hence it is called as impulse turbine.

2. Multi stage arrangement of turbines is called as __________
a) Impulse turbine
b) Reaction turbine
c) Compounding
d) None of the mentioned

View Answer

Answer: c [Reason:] Multi stage arrangement of turbines reduces the pressure loss and velocity losses and hence it is called as compounding.

3. Compounding __________ efficiency at low speed.
a) decrease
b) increase
c) maximizes
d) none of the mentioned

View Answer

Answer: b [Reason:] Even at low speeds velocity wastage is prevented and hence efficiency is increased.

4. In pressure compounded turbines moving nozzles are followed by turbine blades.
a) True
b) False

View Answer

Answer: b [Reason:] In pressure compounding fixed nozzles are followed by moving blades.

5. In pressure compounded turbines flow passage is from ______________
a) moving nozzles to fixed blades
b) fixed nozzles to moving blades
c) fixed blades to moving nozzles
d) none of the mentioned

View Answer

Answer: b [Reason:] In pressure compounded turbines pressure drop is reduced into stages reducing the pressure loss and hence increasing the efficiency. Hence in pressure compounded turbines flow passage if from fixed nozzles to moving blades.

6. In velocity compounded turbines flow passage is from ____________
a) moving blades to fixed nozzles
b) fixed nozzles to moving blades
c) fixed blades to moving nozzles
d) none of the mentioned

View Answer

Answer: d [Reason:] In velocity compounded turbines velocity drop is maintained in stages and hence reducing velocity loses. Hence in velocity compounded turbines flow passage is from fixed nozzles to multiple rows of moving blades alternating with fixed blades.

7. A velocity compounded impulse turbine is also called as __________
a) Curtis wheel
b) Pressure compounded
c) Curtis wheel & Pressure compounded
d) None of the mentioned

View Answer

Answer: a [Reason:] Velocity compounded turbines are invented by a scientist called Curtis and hence it is named after his name.

8. Reaction turbine is also called as _________
a) Impulse turbine
b) Curtis wheel
c) Parsons turbine
d) None of the mentioned

View Answer

Answer: c [Reason:] Reaction turbine was invented by a scientist names Parson and hence it was named after his name.

9. A turbine comprising of fixed blades and moving nozzles is called as reaction turbines.
a) True
b) False

View Answer

Answer: a [Reason:] In reaction turbines the reaction produced when steam hits the turbine is also utilized to produce power output.

10. Compounding is used for _________ power applications.
a) low
b) high
c) medium
d) none of the mentioned

View Answer

Answer: b [Reason:] In compounding high powers are produced at low speeds also. Hence for low power production compounding need not be used.

Set 4

1. Rotating disks are subjected to _______
a) mechanical stress
b) thermal stress
c) mechanical & thermal stress
d) none of the mentioned

View Answer

Answer: c [Reason:] Rotating disks are subjected to both mechanical and thermal stresses.

2. Internal pressure on the disk are due to _______
a) broken fittings
b) expanded fittings
c) shrink fitted on its mountings
d) none of the mentioned

View Answer

Answer: c [Reason:] Internal pressure on disk is caused due to shrink fitted on its mountings.

3. Finite element analysis is done for rotating disk.
a) True
b) False

View Answer

Answer: a [Reason:] Different temperatures are established when hot gasses are passed and hence finite element analysis is done.

4. High stresses in rotating disks are caused due to _______
a) excessive temperature
b) excessive rotating speeds
c) excessive temperature & rotating speeds
d) none of the mentioned

View Answer

Answer: b [Reason:] High stresses in rotating disks are caused due to excessive rotating speeds.

5. Rotational disks deform due to ______________
a) uni symmetrical
b) multi symmetrical
c) axi symmetrical
d) none of the mentioned

View Answer

Answer: c [Reason:] Deformation of rotational disks is axi symmetrical.

6. Gas turbine discs are made of _______
a) Chromium
b) Chrome-Nickel steel alloy
c) Nickel
d) None of the mentioned

View Answer

Answer: b [Reason:] Chrome-nickel steel alloy is used to make gas turbine discs in general.

7. Contact at fastening between blade root and disk staple is ________
a) one dimensional
b) two dimensional
c) three dimensional
d) none of the mentioned

View Answer

Answer: c [Reason:] Three dimensional contact is maintained at fastening between blade root and disk staple.

8. Some of the fasteners are _______
a) Bolts
b) Nuts
c) Keys
d) All of the mentioned

View Answer

Answer: d [Reason:] Keys,Nuts and Bolts are some fasteners in turbine generator steam turbines.

9. ________ are used to secure some fasteners which have tendency to slip or slide away.
a) Bolts
b) Nuts
c) Washers
d) None of the mentioned

View Answer

Answer: c [Reason:] Washers are used to lock fasteners which slip or slide away.

10. Bolts are _______ fasteners.
a) locking fasteners
b) threaded fasteners
c) frictional fastener
d) none of the mentioned

View Answer

Answer: b [Reason:] Bolts are threaded fasteners as they have threading on them.

Set 5

1. Jet engines can be accelerated to supersonic velocities with _______ section.
a) Convergent
b) Divergent
c) Does not depend on shape of the section
d) None of the mentioned

View Answer

Answer: b [Reason:] When fluid passes through divergent section maximum thrust force is provided so that jet engines can be accelerated to supersonic velocities.

2. Nozzles with high pressure ratios have ______ area divergent sections.
a) variable
b) constant
c) maximum
d) none of the mentioned

View Answer

Answer: a [Reason:] When nozzles are operated at high pressure ratios it needs variable divergent sections because each pressure ratio requires a special divergent section.

3. In nozzle the gases expand _________
a) Iso-thermally
b) Iso-entropically
c) Adiabatically
d) None of the mentioned

View Answer

Answer: c [Reason:] No heat loss takes place when gases are expanded in nozzle and hence it is said that gases expand adiabatically in nozzle.

4. Convergent nozzles are used in jet engines upto nozzle pressure ratio of _______
a) 0.8
b) 1.8
c) 2
d) none of the mentioned

View Answer

Answer: b [Reason:] Convergent nozzles are used until the nozzle pressure ratio is 1.8. If the nozzle pressure ratio goes above 1.8 then convergent nozzle will choke.

5. Convergent divergent nozzles used in rocket engines have _________ area ratio.
a) higher
b) lower
c) optimum
d) none of the mentioned

View Answer

Answer: a [Reason:] Convergent divergent nozzles used in rocket engines have high pressure ratio.

6. Over expansion occurs when exit area of nozzle is _________ than primary nozzle.
a) equal
b) smaller
c) greater
d) none of the mentioned

View Answer

Answer: c [Reason:] When exit area of nozzle is greater than primary nozzle then fluid suddenly expands leading to over expansion.

7. When divergent section is added _________
a) exhaust velocity is increased
b) exhaust temperature is increased
c) exhaust pressure is increased
d) none of the mentioned

View Answer

Answer: a [Reason:] When divergent section is added exhaust velocity is increased .

8. What happens when nozzle doesn’t open after the burner is on ?
a) None of the mentioned
b) Thrust force decreases
c) Exit velocity increases
d) Turbine blades get overheat and fails

View Answer

Answer: d [Reason:] When nozzle doesn’t open, turbine blades get overheated and fails.

9. What happens to mach number when divergence angle is 4 degrees ?
a) Mach number drops from 1.10 to 0.45
b) Mach number drops from 2.10 to 1.45
c) Mach number drops from 3.10 to 2.25
d) None of the mentioned

View Answer

Answer: b [Reason:] It was an experimental value obtained from CFD analysis.

10. What happens to mach number when divergence angle is 7 degrees?
a) Mach number drops from 2.5 to 1.5
b) Mach number drops from 3 to 2
c) Mach number drops from 1.5 to 1
d) None of the mentioned

View Answer

Answer: a [Reason:] It was an experimental value obtained from CFD analysis.