Phases of Combustion

Question 1

engine _____ and the combustion process are at their ____ when the exhaust gas is virtually _______

Answer 1

efficiency
best
colorless

Question 2

too much fuel is being injected and the engine smokes this is an indication of ?

Answer 2

incomplete combustion

Question 3

how cleanly the fuel and air mixture burns depends of what 3 factors?

Answer 3

design of combustion chamber
injector type
spray pattern

Question 4

how many phases of combustion are there and name them

Answer 4

3 phases of combustion

ignition delay period
flame spread
direct burning

Question 5

the period from the start of injection until the time combustion begins is known as _________

Answer 5

ignition delay period

Question 6

true or false combustion occurs immediately after fuel is injected into the combustion chamber? explain why

Answer 6

false the delay period heats and vaporizes fuel

Question 7

the delay phase occupies how much degrees of crankshaft rotation?

Answer 7

12 degrees

Question 8

when fuel has now vaporized and mixed with air it ignites. This period is known as?

Answer 8

flame spread

Question 9

the heat in the flame spread period creates what?

Answer 9

rapid rise in pressure

Question 10

the sudden increase in cylinder pressure during the flame spread period is heard as ?

Answer 10

diesel knock

Question 11

the flame spread phases occupies how much degrees of crankshaft rotation?

Answer 11

10-15 degrees

Question 12

the last phase of the phases of combustion is known as ?

Answer 12

direct burning

Question 13

true or false during direct burning phase more fuel is injected directly into the ignited mixture to increase the pressure and force the piston down into the power stroke

Answer 13

true

Question 14

other than combustion chamber design what else can affect the phases of combustion in a CI engine?

Answer 14

Diesel Cetane Rating