15.5 combustion

Question 1

what are the two main components of combustion chamber

Answer 1

combustion chamber casing
the flame tube found in the casing

Question 2

what is the job of the combustion chamber casing

Answer 2

takes the airpressure loads and protects the internal and external engine parts from the hot combustion gasses

Question 3

what can the combustion chamber casing be split into

Answer 3

inner and outer casing

Question 4

what does the flame tube control

Answer 4

controls and guides the flame

Question 5

what is the kerosene-air mixture ratio

Answer 5

15 parts of air for 1 part fuel

Question 6

what is primary airflow used for

Answer 6

used for combustion process - 20%-30% of the airflow from the compressor

Question 7

what is the secondary airflow used for

Answer 7

mixes with hot gas in the dilution zone of the combustion chamber

Question 8

in which zone of the combustion chamber is the flame stabilised

Answer 8

primary zone

Question 9

what are the three different types of combustion chamber `

Answer 9

can type
can annular
annular

Question 10

where can can type combustion chambers be found

Answer 10

old gas turbine engines with centrifugal compressors

Question 11

pros of can type combustion chamber

Answer 11

simple in design
good structural strength
can be removed and replaced individually

Question 12

cons of can type

Answer 12

heavy
need alot of space
complicated air ducts supply
difficult to ignite one chamber to the other

Question 13

pros of can-annular

Answer 13

smaller and lighter than can type

Question 14

con of can-annular

Answer 14

aerodynamic losses are quite high
ignition from one flame tube to another is very difficult

Question 15

what engines use annular

Answer 15

modern gas turbine

Question 16

how many flame tubes in an annular

Answer 16

1

Question 17

what are the 3 major parts of annular

Answer 17

dome
inner liner
outer liner ]

Question 18

what does the dome consist of

Answer 18

openings for fuel nozzels, surrounded by swirl vanes

Question 19

what is an annular combustion chamber specifically designed for small gas turbine engines called

Answer 19

reverse flow annular combustion chamber

Question 20

annular pros

Answer 20

smaller
lighter
better efficiency
complete and smokeless combustioncons

Question 21

cons of annular

Answer 21

expensive
difficult removal

Question 22

what is the construction of annular chamber

Answer 22

combustion case
flame tube
external components fitted to outer wall

Question 23

are igniters fwd or aft of fuel nozzles

Answer 23

aft

Question 24

how many igniters in annular

Answer 24

two igniter plugs
normally on lower half

Question 25

what does the dome section of flame tube connect

Answer 25

inner and outer liner

Question 26

what does the dome section of flame tube house

Answer 26

swirl vanes

Question 27

how is flame tube cooled

Answer 27

secondary airflow forms a cooling film on inner surface of liners known as film cooling

Question 28

what is transpiration cooling

Answer 28

inner surface of flame tube are covered with detachable tiles secondary airflow enters flame tube through radial holes, then flows through the gaps between liner segments and liner

Question 29

what air fuel mixture burns the best

Answer 29

15:1

Question 30

what does a rich fuel mixture lead to

Answer 30

fuel cant be burned and released into exhaust cause a build up of carbon monoxide

Question 31

what can cause an increase in carbon monoxide levels

Answer 31

low combustion temps

Question 32

how to reduce build up of nitrogen oxides

Answer 32

dual dome combustion chamber - reduces the time that exhaust gas is in the hot area