15.5 combustion section

Question 1

what are the following requirements the combustion chamber must fulfil

Answer 1

• it must permit safe ignition of the fuel-air mixture both on ground and in flight
• give stable combustion in all operating conditions of the engine
• combustion must also be complete

Question 2

what are the two primary conditions necessary for correct and safe combustion

Answer 2

• the ratio of air and fuel must be correct
• the air velocity must be slow enough to make sure that the combustion is completed inside the combustion chamber

Question 3

approximately how much of the airflow is from the compressor

Answer 3

20% to 30%

Question 4

what are the three types of combustion chamber

Answer 4

can-type
can-annular
annular

Question 5

what are the two main components on each combustion chamber

Answer 5

1. the combustion chamber casing
2. the flame tube found inside the casing

Question 6

to complete combustion of a kerosene-air mixture, what ratio is needed

Answer 6

15 part air, 1 part fuel (15:1)

Question 7

what does each combustion camber have in can-type camber

Answer 7

1. air supply duct
   2.fuel nozzle
2. flame tube
3. casing

Question 8

what are the advantages of can-type combustion chamber

Answer 8

• simple design
• very good structural strength
• they can be removed and replaced individually

Question 9

what is the advantage of can-annual over multiple-can-type combustions chamber

Answer 9

they are smaller and lighter

Question 10

what are the three major components of an annular combustion chamber

Answer 10

1. the dome
2. the inner liner
3. the outer liner

Question 11

what is the disadvantage of annular combustion chamber

Answer 11

they are expensive to make and removal is very difficult and time consuming

Question 12

what does the combustion case consist of

Answer 12

• outer wall
• inner wall
• diffuser

Question 13

what connects the inner liner with the outer liner on the flame tube

Answer 13

the dome

Question 14

how is the flame tube connected to the combustion case

Answer 14

bolts

Question 15

what is it called if there is too much fuel for the primary air in the combustion chamber

Answer 15

rich mixture

Question 16

what does the combustion chamber casing do

Answer 16

it takes air pressure loads and protects the internal and external engine parts from hot combustion gases

Question 17

what is the disadvantage of can-annual

Answer 17

the aerodynamic losses are quite high and the ignition from one flame tube to the others is very difficult

Question 18

what does the secondary airflow form to help protect the liner from the intense heat of the combustion gases

Answer 18

a cooling film