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M15 Ryan > M15.5 > Flashcards

M15.5 Flashcards

1
Q

What’s the purpose of the combustion chamber?

A

To produce a hot stream of gas for the turbines and jet nozzle

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2
Q

The combustion chamber must be…

A

Small and light
Have a cooling system
A high operating lifetime

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3
Q

Combustion must have a minimum amount of what?

A

Pressure loss

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4
Q

What components comprise the combustion section?

A

Casing
Flame tube

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5
Q

What does the combustion chamber casing do?

A

Take air pressure loads
Protects internal and external parts from hot combustion gasses

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6
Q

What does the combustion chamber housing do?

A

Give support to:
Flame tube
Fuel nozzles
Igniter plugs

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7
Q

What’s the purpose of the flame tube?

A

It controls and guides the flame

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8
Q

How is the flame tube protected from the extreme temps of combustion

A

By using secondary airflow

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9
Q

What will hot spots in the flame tube indicate?

A

Cooling airflow is not correct or the ceramic lining is damaged

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10
Q

What do fuel nozzles do in the combustion chamber?

A

Spray fuel into the centre of the airflow

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11
Q

How is the fuel and air mixture ignited?

A

Electrically with a igniter plug

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12
Q

After combustion has started what happens with ignition?

A

Turned off

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13
Q

What are the 2 primary conditions for safe combustion?

A

The ratio of fuel to air must be kept correct
The airs velocity must be slowed down enough to ensure combustion is completed

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14
Q

What percentage of air from the compressor is used for combustion?

A

20 - 30%

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15
Q

What percentage of air from the compressor is used for cooling?

A

70 - 80%

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16
Q

What is the required fuel to air ratio for combustion?

A

1:15
Fuel:air

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17
Q

What is the primary zone in the combustion chamber?

A

Where the flame stabilises

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18
Q

What is the secondary air used for in the combustion chamber?

A

Keep the flame away from the flame tube walls

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19
Q

What is the secondary zone also known as?

A

The dilution zone

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20
Q

What cooling methods are used on combustion liners?

A

Film cooling and transpiration cooling

21
Q

What are the 3 types of combustion chambers?

A

Can- type
Can-annular
Annular

22
Q

Where are can-type combustion chambers usually found?

A

Old GTE’s with centrifugal compressors

23
Q

What are the advantages of a can-type combustion chamber?

A

Individually removable
Good structural strength
Simple design

24
Q

What are the disadvantages of a can-type combustion chamber?

A

Ignition difficulties
Aerodynamic loss
Large and heavy

25
Q

What are the advantages of a can-annular combination chamber?

A

Structural strength
Simple air supply
Dimension and weight

26
Q

What are the disadvantages of a can-annular combustion chamber?

A

Ignition difficulties
Aerodynamic loss

27
Q

What are the advantages of a annular combustion chamber?

A

Thermal load distribution
Flame propagation
Complete combustion
Efficient
Dimension and weight

28
Q

What are the disadvantages of a annular combustion chamber?

A

Maintenance costs
Manufacturing costs

29
Q

What type of combustion chamber is most common on modern a/c?

A

Annular type

30
Q

The annular combustion chamber case carries structural loads between what?

A

Compressor case
Turbine case

31
Q

What does the flame tube do?

A

Stabilises and controls the flame

32
Q

Why is a flame tube only secured at one end?

A

To allow for thermal expansion

33
Q

What is the purpose of the diffuser?

A

To reduce velocity of airflow coming from the compressor

34
Q

The combustion case assembly is made up of what?

A

Outer wall
Inner wall
Diffuser

35
Q

Why is the rear part of the inner wall on the combustion case removable?

A

To allow for access to the flame tube

36
Q

What’s the purpose of the combustion case?

A

Part of the load carrying structure of the engine, protects engine parts from excess heat and provides mounts for the combustion chambers components

37
Q

How many igniter plugs are there usually in the combustion case?

A

2

38
Q

What’s fitted to the combustion case for Maintenance?

A

Borescope ports

39
Q

What does the compressor rear frame house?

A

Bearings for high pressure rotor

40
Q

What does the dome section of the flame tube do?

A

Connects inner and outer liners
Also houses swillers and swill vanes

41
Q

What is the outer liner of the flame tube attached to?

A

Inner surface of the outer wall in a axial direction only by a recess

42
Q

How is the inner liner support for the flame tube attached?

A

Bolted to inner wall of combustion case

43
Q

How is the dome centred in the combustion case?

A

By mounting pins

44
Q

How does primary airflow enter the flame tube?

A

Through swill vanes

45
Q

How does secondary airflow enter the flame tube?

A

Passes the cowl and enters via liners

46
Q

What are the 3 types of film cooling?

A

Machined cooling
Corrugated strip cooling
Splash cooling strip

47
Q

What’s the advantage and disadvantage of transpiration cooling?

A

Requires less air but is Sophisticated

48
Q

What is the inner surface of the flame tube covered with in the transpiration cooling method?

A

Detachable tiles called liner segments

49
Q

How do liner segments allow for cooling?

A

By allowing air to flow between the segments and liner

M15 Ryan (17 decks)

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