15.5

Question 1

Important requirement of combustion

Answer 1

It must be complete , no unburnt fuel leaves the combustion chamber

Question 2

What important about combustion chamber outlet

Answer 2

Equal temperature distribution, especially at first turbine stage

Question 3

3 requirements of combustion chamber

Answer 3

Small and light

Dependable cooling system

High operating lifetime

Question 4

Why do we need a small and light chamber

Answer 4

To save weight

Question 5

What’s the problem with replacing engine components in the combustion chamber

Answer 5

It’s very time consuming

Question 6

2 parts of combustion chamber

Answer 6

Casing (can be inner and outer)

Flame tube

Question 7

What does the casing do

Answer 7

Outer shield that takes air pressure loads and protects external engine parts

Question 8

What does the housing support

Answer 8

Flame tube and other combustion chamber components (fuel nozzle and igniter plugs)

Question 9

What does the flame tube do

Answer 9

Control and guides the flame

Made of segments and had lots of holes and slots

Question 10

Conditions for correct and safe combustion

Answer 10

Correct fuel to air ratio

Air velocity slow enough to make sure combustion is completed inside the chamber

Question 11

Kerosene air fuel mix ratio

Answer 11

15 parts air 1 part fuel

15:1

Question 12

What air is used for combustion process

Answer 12

Primary

Question 13

What % of air is primary from the compressor

Answer 13

20-30%

Question 14

What part of the chamber does the flame stabilise

Answer 14

Primary zone

Question 15

3 types of combustion chambers

Answer 15

Can-type

Can-annular

Annular

Question 16

Where are can-type combustion chambers used

Answer 16

Old gas turbines with centrifugal compressors

Question 17

Advantage of can-type

Answer 17

Simple and goodstructural strength

Removed and replaced individually

Question 18

Disadvantage of can-type

Answer 18

Difficult ignition from one chamber to another

Question 19

Advantage on can-annular

Answer 19

Smaller and lighter than a similar multiple can-type combustion chamber

Question 20

Disadvantage of can-annular

Answer 20

Poor ignition from flame tubes and aerodynamic loses are high

Question 21

What’s the most used combustion chamber construction

Answer 21

Annular

Question 22

How does annular combustion chamber work

Answer 22

One annular flame tubes supported by inner and outer chamber casing

Question 23

3 parts of annular construction

Answer 23

Dome

Inner liner

Outer liner

Question 24

Why is annular a reverse flow combustion chamber

Answer 24

Airflow direction in the flame tube

Question 25

Disadvantage of annular

Answer 25

Expensive to make and removal is very difficult and time consuming

Question 26

Annular construction

Answer 26

Combustion case Flame tube External components fitted to the outer wall

Question 27

Annular combustion case construction

Answer 27

Outer wall Inner wall Diffuser

Question 28

Why is the inner wall removable and what does it attach

Answer 28

Removable so the flame tube can be installed Attaches the nozzle guide vanes HPT and support flame tube

Question 29

What are stator vanes also known as

Answer 29

Exit guide vanes

Question 30

How many igniter plugs are installed

Answer 30

2

Question 31

Flame tube components

Answer 31

Outer and inner liner Outer and inner cowl Dome

Question 32

How does primary air enter the flame tube

Answer 32

Swirl vanes

Question 33

How does secondary air enter the flame tube

Answer 33

Passed the cowl and enters through liners

Question 34

What is film cooling

Answer 34

Secondary airflow forms a film to protect the liner from intense heat of combustion gases

Question 35

What is transpiration cooling

Answer 35

Inner surface of flame tubes liner covered with detachable tiles

Question 36

How does secondary air get into the liner

Answer 36

Radial holes

Question 37

What does excessive fuel cause a build up of

Answer 37

Carbon monoxide

Question 38

What does an increase in combustion temperature have an effect on

Answer 38

Decrease carbon monoxide and hydrocarbon emissions Increase nitrogen oxide emissions and vice versa

Question 39

What’s a benefit of dual dome combustion chambers

Answer 39

Shorter then standard chambers

Question 40

What’s the advantage of shorter combustion chambers

Answer 40

Reduces time the exhaust gas is in the hot area and build up of nitrogen oxides

Question 41

What’s a rich mix

Answer 41

Too much fuel for primary air in the combustion chamber

Question 42

What’s a lean mix

Answer 42

Not enough fuel for the combustion chamber

Question 43

What does the dome do

Answer 43

Connect the inner and outer liner

Question 44

What is the outer liner and dome made in

Answer 44

One piece

Question 45

How is the dome centred

Answer 45

By mounting pins

Question 46

Where is the inner liner bolted to

Answer 46

Inner flange of HPT nozzle guide vanes