M15.5 Combustion Section

Question 1

Combustion chamber main components

Answer 1

• combustion chamber casing
• Flame tube

Question 2

Functions of combustion for safe flight

Answer 2

• Safe ignition (Ground and air)
• Stable ops
• Complete combustion

Question 3

When are the igniter plugs switched off

Answer 3

After ignition

Question 4

Kerosine-air mixture ratio

Answer 4

1:15 (K to A)

Question 5

How much of the compressor air is used for primary combustion

Answer 5

20-30%

Question 6

What is secondary air used for

Answer 6

• Cooling
• Flame control

Question 7

How does secondary air enter the dilution zone

Answer 7

Dilution air holes

Question 8

Low or high velocity for combustion

Answer 8

Low

Question 9

What should the air velocity be for combustion or kerosine-air mixtures

Answer 9

2-15 m/s

Question 10

Types of combustion chamber

Answer 10

• Can
• Can-annular
• Annular

Question 11

What combustion chamber is used on engines with centrifugal compressors

Answer 11

Can type

Question 12

How is ignition transferred in can type combustion chambers

Answer 12

Interconnector tubes

Question 13

What do the interconnector tubes do

Answer 13

• Transfer ignition
• Equalise pressurisation

Question 14

Advantages of can type

Answer 14

• Simple
• Good strength
• Replaced individually

Question 15

Disadvantage of can type combustion

Answer 15

Heavy and need space

Question 16

What is the common part in a can annular combustion chamber

Answer 16

Common outer ring and inner casing

Question 17

Advantage of can-annular combustion

Answer 17

• Smaller than multiple can type
• Good strength

Question 18

Disadvantage of can-annular combustion

Answer 18

• High aerodynamic losses
• Ignition can be hard to pass

Question 19

Advantages of annular chambers

Answer 19

• Small but light
• Better efficiency
• Better thermal distribution
• Smokeless

Question 20

Disadvantage of annular chambers

Answer 20

Expensive and difficult to remove

Question 21

An increase in combustion temp will do what to carbon monoxide and nitrogen oxide emissions

Answer 21

• Decrease carbon monoxide
• Increase Nitrogen Oxide

Question 22

Apart from fuel mixture how can emissions be lowered

Answer 22

Dual zone combustion chambers

Question 23

What is in front of the inner wall flange

Answer 23

Seal surface of the CDP (Compressor Discharge Seal)

Question 24

What is film cooling

Answer 24

Secondary airflow is used to cool the inner surface of the liners

Question 25

What type of flame tube cooling is used on modern engines

Answer 25

Machined cooling rings

Question 26

What type of flame tube cooling is used on older engines

Answer 26

- Corrugated Strip Cooling - Splash cooling strip

Question 27

What is the most sophisticated type of flame tube cooling

Answer 27

Transpiration cooling method