Combustion in Engines

 

TOTAL MECHANICAL ENGINEERING

Section 1	Section 2	Section 3	Section 4
Section 5	Section 6	Section 7	Section 8

Combustion in Engines

Quiz

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1. In spark ignition engines knocking tendency decreases
   1.   As compression ratio is reduced
   2.   By controlling ignition timing
   3.   by controlling air-fuel mixture
   4.   none of these
2. Knocking take place in CI engines
   1.   At the start of combustion
   2.   at the end of combustion
   3.   during combustion
   4.   none of these
3. HUCR is the compression ratio at which
   1.   Fuel can be used with detonation
   2.   Fuel can be used without detonation
   3.   An engine gives maximum thermal efficiency
   4.   none of the above
4. Decreasing the cooling water temperature in SI engines the knocking tendency
   1.   Increases
   2.   Decreases
   3.   Not affected
   4.   none of these
5. In a CI engine higher combustion chamber wall temperature will
   1.   Reduce exhaust temperature
   2.   Reduce knocking tendency
   3.   increase knocking tendency
   4.   have no effect
6. In SI engine flame speed increases
   1.   With turbulence
   2.   with advancing spark
   3.   with early closing of exhaust valve
   4.   none of these
7. Which type of head is not used in SI engine?
   1.   F head
   2.   T head
   3.   I head
   4.   M type head
8. The charge in a CI engine is always
   1.   Stoichiometric
   2.   heterogeneous
   3.   homogeneous
   4.   none of these
9. In CI engines, knocking tendency increases with
   1.   Increase in compression ratio
   2.   Increase in inlet temperature of air
   3.   decrease in compression ratio
   4.   increasing coolant water temperature
10. In CI engines with increase in compression ratio the delay period
    1.   Increases
    2.   decreases
    3.   first increases and then decreases
    4.   not affected
11. Increasing the compression ratio in SI engines the knocking tendency
    1.   Decreases
    2.   increases
    3.   not affected
    4.   none of these
12. Desirable characteristics of the combustion chamber for SI engines to avoid knock is
    1.   Small bore
    2.   Short ratio of flame path to bore
    3.   absence of hot surfaces in the last region of the charge
    4.   all of the above
13. Open combustion chambers in CI engines require
    1.   High injection pressures
    2.   Accurate metering of fuel by the injection system
    3.   both (a) and (b)
    4.   none of these
14. Detonation in SI engines occur due to
    1.   Preignition of the charge before the spark
    2.   Sudden ignition of the charge before the spark
    3.   auto ignition of the charge after the spark is struck
    4.   none of these
15. In CI engines by increasing inlet air pressure the knocking tendency
    1.   Increases
    2.   decreases
    3.   not affected
    4.   first decreases and then increases