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Total Questions : 1124 | Page 49 of 113 pages
Question 481.
 
In a diesel engine, the duration between the time of injection and ignition, is known as
  1.    pre-ignition period
  2.    delay period
  3.    period of ignition
  4.    burning period
 Discuss Question
Answer: Option B. -> delay period


Question 482.
 
In open
combustion chamber in diesel engines, the shape and layout of the piston
crown, the inlet port and the valve produce the turbulent effect of
fuel mixture.
  1.    True
  2.    False
 Discuss Question
Answer: Option A. -> True


Question 483.

 
The object of supercharging the engine is


  1.    to reduce mass ofthe engine per brake power
  2.    to reduce space occupied by the engine
  3.    to increase the power output of an engine when greater power is required
  4.    all ofthe above
 Discuss Question
Answer: Option D. -> all ofthe above


Question 484.

 
The expansion of fuel in a four stroke cycle diesel engine


  1.    starts at` 15^circ` before top dead centre and ends at `30^circ` after top dead centre
  2.    starts at top dead centre and ends at `30^circ` after top dead centre
  3.    starts at `15^circ` after top dead centre and ends at`30^circ` before bottom dead centre
  4.    may start and end anywhere
 Discuss Question
Answer: Option C. -> starts at `15^circ` after top dead centre and ends at`30^circ` before bottom dead centre


Question 485.

 
In diesel
engines, the fuel is injected in the form of very fine spray, into the
engine cylinder, which gets ignited due to high temperature of the
compressed air.


  1.    Agree
  2.    Disagree
 Discuss Question
Answer: Option A. -> Agree


Question 486.

 
Pre-ignition is caused by the spontantaneous combustion of the mixture before the end of the compression stroke, and is due to


  1.    cylinder walls being too hot
  2.    overheated spark plug points
  3.    red hot carbon deposits on cylinder walls
  4.    any one of these
 Discuss Question
Answer: Option D. -> any one of these


Question 487.


 
The brake power of a diesel engine, keeping other parameters constant, can be increased by


  1.    decreasing the density of intake air
  2.    increasing the temperature of intake air
  3.    increasing the pressure of intake air
  4.    decreasing the pressure of intake air
 Discuss Question
Answer: Option C. -> increasing the pressure of intake air


Question 488.

The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called


  1.    mechanical efficiency
  2.    overall efficiency
  3.    volumetric efficiency
  4.    relative efficiency
 Discuss Question
Answer: Option C. -> volumetric efficiency


Question 489.


A moderator generally used in nuclear power plants is


  1.    graphite
  2.    heavy water
  3.    concrete
  4.    graphite and concrete
 Discuss Question
Answer: Option D. -> graphite and concrete


Question 490.

The exhaust valve in a four stroke cycle petrol engine


  1.    opens at `50^circ`before bottom dead centre and closes at `15^circ` after top dead centre
  2.    opens at bottom dead centre and closes at top dead centre
  3.    opens at` 50^circ` after bottom dead centre and closes at `15^circ` before top dead centre
  4.    may open and close anywhere
 Discuss Question
Answer: Option A. -> opens at `50^circ`before bottom dead centre and closes at `15^circ` after top dead centre


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