15.04 Flashcards

1
Q

What material is the fan rotor disc made from

A

Titanium alloy

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2
Q

Which type of compressor axial or centrifugal is more efficient

A

Axial

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3
Q

Where would you most likely find a centrifugal flow compressor

A

Small gas turbine engine e.g APU

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4
Q

Why does a cone have a spiral or white markings

A

To scare birds away

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5
Q

Which type of compressor axial or centrifugal has a good efficiency over a wide speed range

A

Centrifugal

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6
Q

What is the first part of a compressor stage

A

The rotor

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7
Q

What unit can the moment weigh of a blade be given in

A

Gram/inches
cmg
Oz inches

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8
Q

What type of fan blade attachment is used on most engines

A

Dovetail fitting

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9
Q

What makes up the compressor stage

A

Rotor & stator

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10
Q

What two ways can you compress air in engines

A

Decrease the volume by a piston

Make use of Bernoulli Principal

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11
Q

What happens when the impeller rotates

A

Air is sucked horizontally near the centre of the impeller

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12
Q

What is the spinner cone also known as

A

Compressor inlet cone or nose cone

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13
Q

What is the forward part and aft part of a dual spool engine called

A

LP compressor N1 and HP compressor N2

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14
Q

When can a compressor stall

A

Speed of engine is too far BELOW the design speed

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15
Q

What pressure ratio can the centrifugal flow compressor give

A

About 5:1

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16
Q

What is the rear drum of a rotor assembly bolted to

A

Rear hub

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17
Q

What is the advantage of wide chord fan blade than to conventional blades

A

More efficient

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18
Q

How are the stator vanes installed on a split stator case

A

Two stator halves bolted together afterward

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19
Q

What axis does airflow in an axial flow compressor flow along

A

Horizontal axis

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20
Q

Can fan blades be manufactured to have the same moment weights

A

NO!!

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21
Q

What would you do if one blade is damage

A

Change the pair instead of one blade

22
Q

What is the fan blade containment made of

A

Honeycomb construction covered by Kevlar

23
Q

How are the stator vanes fitted on a closed stator case

A

Fitted to the shrouds between the rotor stages

24
Q

Which compressor axial or centrifugal has a very high pressure rise per stage

A

Centrifugal

25
Q

Which compressor axial or centrifugal is cheaper to manufacture

A

Centrifugal

26
Q

Which compressor axial or centrifugal needs less power for engine start and weight less

A

Centrifugal

27
Q

How many compressor stages does a modern engine have

A

9 up to 14

28
Q

What is the best method to change the engine fan blade

A

Replace the fan blade with a new blade with the moment weight as close to the old blade

29
Q

What are the main components of a centrifugal flame w compressor

A

Diffuser
Impeller
Compressor manifold

30
Q

What is another name for a low pressure compressor rotor

A

Booster rotor

31
Q

What is the pressure ratio of each stage of an axial flow compressor

A

1:3:1

32
Q

How many stages of pressure increase can you have in a centrifugal flow compressor

A

2 As pressure decrease when airflow goes from first stage to second stage

33
Q

What two main components does a compressor have

A

Compressor rotor

Compressor stator

34
Q

What is a double faced compressor

A

Two impeller mounted face to face

35
Q

If the moment is larger than specific by manufacturer what can be used

A

Balance weights

36
Q

How can you identify fan blade one

A

Index mark or offset hole

37
Q

How is the labyrinth seal made

A

By knife edges on the rotor drum and the opposing shrouds of the stator assembly

38
Q

How can you get a smooth airflow on an axial compressor

A

Make sure angle of attack on rotor blade is small

39
Q

What do the compressor inlet/outlet cases support

A

Give support for the compressor rotor bearings

40
Q

Which compressor axial or centrifugal causes less drag on engines

A

Axial as it has a smaller frontal area

41
Q

What do the OGV improve

A

The airflow into the fan nozzle

42
Q

What are the three methods used to prevent compressor stall and surge

A
  1. Use compressor bleed valve
  2. Use dual or triple spool rotors instead of single
  3. Use variable compressor stator vanes (most modern)
43
Q

What are the two types of compressor

A

The axial flow compressor

The centrifugal flow compressor

44
Q

Compressor with high compression ratios will have what

A

VSV In the first stages

45
Q

What are the bells held in place by

A

Blade retainers

46
Q

What do IGV improve

A

The airflow into the first compressor stage

47
Q

Where is bleed air supplied through in a compressor

A

Supplied through hollow stator vanes or through holes in the outer platform of the stator vane

48
Q

What does a labyrinth seal do

A

Prevents reverse air flow

49
Q

What is a severe form of compressor stall

A

Compressor surge

50
Q

What happens when the air passes through the diffuser

A

Velocity decreases and pressure increases

51
Q

What three ways can you fit blades onto a HP compressor

A

Blade retainers
Locking lug
Bolts