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Multiple choice question for engineering

Set 1

1. Gas turbine diffuser _________ the production of energy.
a) increases
b) decreases
c) remains constant
d) none of the mentioned

View Answer

Answer: b [Reason:] Gas turbine diffuser increases the production of energy.

2. Gas turbine diffusers ________ the speed of the flow.
a) increases
b) reduces
c) remains constant
d) none of the mentioned

View Answer

Answer: a [Reason:] Gas turbine diffuser increases the speed of the flow.

3. Movement speed of motor shaft is _________ when diffuser is used.
a) decreased
b) increased
c) remains constant
d) none of the mentioned

View Answer

Answer: b [Reason:] Motor shaft speed is increased when diffuser is used. When diffuser is used it converts the pressure energy of the gas into rotation of motor shaft and diffuses the working fluid.

4. In automobiles diffuser _________ the down force.
a) decrease
b) minimizes
c) increases
d) none of the mentioned

View Answer

Answer: c [Reason:] In automobiles diffuser allow the air to escape from outside and as a result down force increases.

5. In jet engines diffusers are used __________
a) At low speeds
b) At Supersonic speeds
c) Not related to speed at all
d) None of the mentioned

View Answer

Answer: b [Reason:] Diffuser allows extra air to escape and as a result aerodynamic properties increases and hence diffuser is used in jet engine when operated at supersonic speeds.

6. Diffuser is installed after turbine where air passes the turbine first then passes through diffuser.
a) True
b) False

View Answer

Answer: b [Reason:] Diffuser is installed between vanes and turbine where air after passing through the diffuser enters the vanes.

7. In centrifugal compressor diffuser is used in a channel ________ the vanes.
a) before
b) after
c) between
d) none of the mentioned

View Answer

Answer: c [Reason:] In a centrifugal compressor diffuser is used in a channel between vanes.

8. Diffusers are also used in underwater breathing systems.
a) True
b) False

View Answer

Answer: a [Reason:] Diffusers are used in under water breathing systems so that bubble formation is reduced.

9. Diffuser ___________ velocity air.
a) depends o the situation
b) slows
c) increases
d) none of the mentioned

View Answer

Answer: c [Reason:] Diffuser is used in compressor section and slows down the high velocity air and increases the pressure.

10. Diffuser changes the ______________ to longitudinal direction.
a) parallel flow
b) radial direction
c) perpendicular flow
d) none of the mentioned

View Answer

Answer: b [Reason:] Diffuser changes the radial air flow direction into longitudinal direction.

Set 2

1. Governors are used to control speed to ________
a) fuel input ratio
b) fuel input
c) fuel input ratio & fuel input
d) none of the mentioned

View Answer

Answer: a [Reason:] In governors when speed is increased its throttle increases and more fuel enters which indicates governors are used to control speed to fuel input ratio.

2. Speed/Load control is used to determine the __________ for available load.
a) speed limitation
b) power demand
c) speed limitation & power demand
d) none of the mentioned

View Answer

Answer: b [Reason:] Speed/Load control is used to determine the fuel demands according to the increase or decrease in load.

3. In aviation jet engine minimum fuel available should be limited during deceleration to avoid ______
a) shut down of the engine
b) combustion blow out
c) to control the load
d) none of the mentioned

View Answer

Answer: b [Reason:] In aviation jet engine minimum fuel available is limited during deceleration to avoid combustion blow out.

4. In steam turbines governors are used to control __________
a) Isochronic operations
b) Drop operations
c) Isochronic & Drop operations
d) None of the mentioned

View Answer

Answer: c [Reason:] In general speed responsive governors are used during isochronic and drop operations.

5. The change in fuel flow is called as ________
a) speed error
b) fuel error
c) speed & fuel error
d) none of the mentioned

View Answer

Answer: a [Reason:] The difference between actual value and reference value of speed is called an error and change in fuel flow is called as speed error.

6. In drop control __________ is constant.
a) turbine speed
b) reference value
c) turbine speed & reference value
d) none of the mentioned

View Answer

Answer: b [Reason:] In drop control fuel is controlled by changing the speed error where turbine speed is kept constant by the grid.

7. In drop control fuel flow is directly proportional to _____________
a) turbine speed
b) temperature
c) speed error
d) none of the mentioned

View Answer

Answer: c [Reason:] In drop control the turbine speed is maintained constant and fuel flow is directly proportional to speed error, so to change the fuel flow reference value is either increased or decreased.

8. In drop control if the turbine speed was not constant at the grid then speed would __________
a) raise
b) drop
c) remains constant
d) none of the mentioned

View Answer

Answer: b [Reason:] In drop control turbine speed is remained constant and speed error is varied by changing reference value.

9. In drop governor at 100% turbine speed the output is __________
a) 50%
b) 40%
c) 60%
d) none of the mentioned

View Answer

Answer: a [Reason:] To obtain 50% output the speed should be 100%. This can be obtained from graph.

10. When set point is increased to 103% the output is __________
a) 60%
b) 50%
c) 75%
d) none of the mentioned

View Answer

Answer: a [Reason:] From graph it can be obtained that when set point is 103% its output is 75%.

Set 3

1. When mach number is less than 1 flow is __________
a) Subsonic flow
b) Transonic flow
c) Supersonic flow
d) None of the mentioned

View Answer

Answer: a [Reason:] For subsonic flow mach number is always less than one.

2. When mach number is equal to one then the flow is ___________
a) Subsonic flow
b) Transonic flow
c) Supersonic flow
d) None of the mentioned

View Answer

Answer: b [Reason:] For transonic flow mach number is equal to one.

3. When mach number is greater than one flow is ___________
a) Subsonic flow
b) Transonic flow
c) Supersonic flow
d) None of the mentioned

View Answer

Answer: c [Reason:] For supersonic flow mach number is always greater than one.

4. For subsonic flow density varies relatively.
a) True
b) False

View Answer

Answer: b [Reason:] For subsonic flow density is relatively constant.

5. For transonic flow density change is ________ velocity change.
a) equal to
b) more than
c) less than
d) none of the mentioned

View Answer

Answer: a [Reason:] For transonic flow density change is almost equal to velocity change.

6. For supersonic flow density changes ___________ velocity change.
a) faster than
b) slower than
c) equal to
d) none of the mentioned

View Answer

Answer: a [Reason:] For supersonic flow density change is faster than velocity change.

7. In a supersonic flow density change is faster than velocity change by a factor of _________
a) Mach number
b) Square of mach number
c) Cube of mach number
d) None of the mentioned

View Answer

Answer: b [Reason:] In supersonic flow density change is greater than velocity change by a factor of square of mach number.

8. For compressible flow mach number must be ____________ 0.3
a) less than
b) equal to
c) greater than
d) none

View Answer

Answer: c [Reason:] For compressible flow mach number should be greater than 0.3.

9. When normal shock waves occurring at an angle ____________ 90 degree then they are called as bow shock.
a) less than
b) greater than
c) equal to
d) none of the mentioned

View Answer

Answer: b [Reason:] When normal shock waves occurring at an angle less than 90 degree they are called as oblique shock waves.

10. When oblique shock _________ the flow it is called as bow shock.
a) detached from
b) added to
c) minimizes
d) none of the mentioned

View Answer

Answer: a [Reason:] Due to flow conditions oblique shock may be attached or detached with flow, When oblique shock wave is detached with flow it forms a bow shock.

Set 4

1. In nozzle governing flow rate is controlled by only ______________
a) closing nozzle
b) opening nozzle
c) closing & opening nozzle
d) none of the mentioned

View Answer

Answer: b [Reason:] In nozzle governing flow rate is controlled by either opening or closing the valves.

2. ________ is regulated in nozzle governing.
a) Pressure
b) Temperature
c) Flow rate
d) None of the mentioned

View Answer

Answer: c [Reason:] In nozzle governing flow rate is controlled by opening or closing the valves instead of regulating the pressure.

3. In nozzle governing Every nozzle is controlled by a separate valve.
a) True
b) False

View Answer

Answer: a [Reason:] In nozzle governing each nozzle is controlled by a separate valve.

4. In turbine nozzle governing is applied on _________
a) 2nd stage
b) 1st stage
c) Final stages
d) None of the mentioned

View Answer

Answer: b [Reason:] In turbine nozzle governing is applied in first stage and remaining stages will be un affected.

5. Remaining stages of the turbine other than first stage remains ____________ in nozzle governing.
a) unaffected
b) affected
c) unaffected & affected
d) none of the mentioned

View Answer

Answer: a [Reason:] Nozzle governing is applied only in first stage and remaining stages are unaffected as no pressure regulation is applied.

6. ________ boiler pressure can be obtained from nozzle governing.
a) Depends on the load
b) Partial
c) Full
d) None of the mentioned

View Answer

Answer: c [Reason:] Full boiler pressure can be obtained as no pressure regulation is done.

7. _________ boiler temperature can be utilized by this nozzle governing.
a) Full
b) Partial
c) Depends on the load
d) None of the mentioned

View Answer

Answer: a [Reason:] As there is no pressure regulation temperature also does not change and hence full boiler temperature can be used.

8. In subsequent stages of turbine pressure regulation is done.
a) True
b) False

View Answer

Answer: b [Reason:] In subsequent stages of turbine pressure regulation is not done.

9. In nozzle when entropy ___________ supersaturation occurs.
a) increases
b) decreases
c) remains constant
d) none of the mentioned

View Answer

Answer: a [Reason:] In nozzle supersaturation causes increase in entropy.

10. When mass flow rate is maximum nozzle chokes.
a) True
b) False

View Answer

Answer: a [Reason:] Nozzle chokes when mass flow rate is maximum or during critical conditions.

Set 5

1. When boiler pressure is increased efficiency is ____________
a) decreased
d) increased
c) remains constant
d) none of the mentioned

View Answer

Answer: b [Reason:] When boiler pressure is increased efficiency is increased.

2. Why is operating pressure of boiler designed ?
a) To maintain economic equivalence
b) For not decreasing efficiency
c) No such operating pressures are designed
d) None of the mentioned

View Answer

Answer: a [Reason:] If boiler pressure is increased efficiency also increases. But if we keep on increasing boiler pressure to increase efficiency, Boilers that work under high pressure as costly and so boiler operating pressures are designed so that for a particular boiler it does not work beyond that pressure and it maintains economical equivalence.

3. When boiler pressure is increased __________
a) efficiency is increased
d) Qh is increased
c) efficiency & Qh is increased
d) none of the mentioned

View Answer

Answer: c [Reason:] When boiler pressure is increased Qh increases as a result efficiency is increased.

4. Can we keep on increasing the pressure of the boiler to increase its efficiency ?
a) Yes
b) No

View Answer

Answer: b [Reason:] Boilers that work under high pressure are much more costly.

5. What happens to the efficiency when temperature is increased in rankine cycle ?
a) Increased
b) Decreased
c) Remains constant
d) None of the mentioned

View Answer

Answer: a [Reason:] When temperature is increased reheating capacity of the steam increases and thus efficiency also increases.

6. Increase in temperature increases __________
a) reheating capacity of the fluid
b) thermal efficiency
c) reheating capacity of the fluid & thermal efficiency
d) none of the mentioned

View Answer

Answer: c [Reason:] When reheating capacity is increased it automatically increases the thermal efficiency.

7. When condenser pressure is lowered efficiency _________
a) increases
b) decreases
c) does not effect
d) none of the mentioned

View Answer

Answer: a [Reason:] When operating pressure of condenser is lowered , Heat rejecting temperature also lowers which eventually increases the efficiency.

8. Superheating the steam increases the efficiency.
a) True
b) False

View Answer

Answer: a [Reason:] Average Temperature of steam can be increased without increasing the pressure by superheating.

9. Superheating the steam results in __________
a) increasing the efficiency
b) decreases the moisture content
c) both of the mentioned
d) none of the mentioned

View Answer

Answer: c [Reason:] Superheating the steam increases the steam temperature and also decreases the moisture content in the steam.

10. When boiler pressure is increased __________
a) temperature also increased
b) efficiency also increases
c) both of the mentioned
d) none of the mentioned

View Answer

Answer: a [Reason:] When boiler pressure is increased steam temperature increases which increases the efficiency.

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