Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

M15 Ryan > M15.4 > Flashcards

M15.4 Flashcards

1
Q

What are the 2 main components of the compressor?

A

Compressor rotor
Compressor stator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does the compressor rotor do to the energy?

A

Increases its energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the compressor rotor do?

A

Rotates around the axis of the compressor the rotator blades suck in air and push it to the outlet side of the rotor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the stator do to the airflow?

A

Guide and slow the airflow to cause an increase in pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the compressor stage?

A

A combination of a rotor and stator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the first part of the compressor stage, rotor or stator?

A

Rotor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What type of combustion chamber is on turbo shaft engines?

A

Reverse flow combustion chamber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a inlet guide vane?

A

The first stator vane of the compressor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the outlet guide vane?

A

The stator vanes that are in the fan duct
(Or the last stator vane of the compressor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does the inlet/outlet compressor case do?

A

Give support to the compressor rotor bearings as well as improve and straighten airflow in and out of the compressor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 2 types of compressor?

A

The axial flow compressor
The centrifugal flow compressor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where is the centrifugal flow compressor usually found?

A

On small GTE’s such as APU

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the main components of the centrifugal flow compressor?

A

Impeller
Diffuser
Compressor manifold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does the centrifugal compressor work?

A

The rotation of the impeller sucks air in and pushes air outwards by centrifugal force to increase velocity and the energy of air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the ratio for centrifugal flow compressor?

A

5:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why do some engines use multiple compressor stages?

A

To give higher pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How many stages are efficient in a multi stage compressor?
And why?

A

2
Because of the pressure decrease that occurs when the airflow changes direction between stages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the double face compressor?

A

When 2 impellers are mounted face to face

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the advantage and disadvantage of the double face compressor?

A

It doesn’t give higher pressure but it has a higher airflow as well as being light weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where Does airflow flow in a axial flow compressor?

A

Along the horizontal axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What’s special about the rotor blades in a axial flow compressor?
And what does this allow?

A

They are aerodynamically shaped

Allows a smoother airflow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why are the channels between the rotor blades diffusers?

A

To increase velocity and to slow airflow down to increase the static pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the ratio for axial flow compressor?

A

1.3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why does the air need less volume in a axial flow compressor?

A

Because as the pressure increases the density does as well

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why is the case of a axial flow compressor tapered?

A

To increase dynamic pressure and maintain velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does a divergent duct do?

A

Creates dynamic and static airflow in one

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are axial and centrifugal compressors sensitive to?

A

Changes in airflow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the design point?

A

Where the airflow in the compressor is perfect matched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How big does the angle of attack have to be on the blade of the compressor?

A

Very small

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What determines the angle of attake on a compressor?

A

The resultant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is needed for a smooth airflow into the rotor?

A

The correct relationship between the inlet velocity and rotor speed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

The direction of airflow in a compressor is called what?

A

Resultant rotor inlet velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

The stator vanes in the compressor do what?

A

Slow the airflow and guide it to the next rotor stage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What happens to airflow in a compressor stall?

A

Angle of attack increases and inlet air velocity decreases
The airflow will also separate from the aero foil and cause a turbulent vortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

A compressor stall causes the airflow to do what?

A

Slow down, stop or reverse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is compressor surge?

A

When stall becomes strong and affects all compressor stages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What happens to low pressure zones during compressor surge?

A

Airflow will stop and reverse its direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Where can surge occur?

A

Fwd or aft compressor stages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Surge in the aft stages of compressor does what?

A

Develops very rapidly over a large part of the compressor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Surge in fwd part of compressor does what?

A

Affects only a small part of the compressor blades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What happens to airflow when compressor surge occurs?

A

Airflow will collapse and build up again at very short intervals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What does compressor surge come with?

A

Heavy vibrations and loud banging noises

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What 3 things happens to engine parameters during compressor surge?

A

Thrust will decrease
Engine fluctuates
EGT rises

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Why does surge or stall happen?

A

Damaged rotor blades and stator vanes
Dents or ice on inlet
Dirty compressor blades
Broken combustor components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What are the 2 ultimate reasons for stall or surge

A

If speed of engine is below design speed
Fast deceleration (meaning compressor rotates too slow)

46
Q

During fast deaccelration how does surge happen?

A

Because the speed of the hp compressor decreases faster then lp compressor

47
Q

What are the 3 methods to avoid surge and stall?

A

Compressor bleed valves
Duel or Triple spool rotors instead of a single spool
Variable compressor stator vanes

48
Q

Where are compressor bleed vanes found?

A

In mid or aft section of compressor

49
Q

When does the compressor bleed valve open?

A

At low engine speeds

50
Q

What causes a big loss in efficiency in a compressor?

A

When airflow is compressed first and then blown overboard

51
Q

On dual spool engines the fwd part is called what?

A

Lp compressor or N1 compressor

52
Q

On a dual spool engine the aft part is called what?

A

Hp compressor or N2 compressor

53
Q

What is the compressor rotor driven by?

A

A turbine

54
Q

Why does a multi spool engine have great acceleration capability?

A

Because of the small rotor mass of the split rotors

55
Q

What is the most efficient method to prevent a stall?

A

Variable stator vanes

56
Q

Where are variable stator vanes found?

A

In the fwd area of the hp compressor

57
Q

What is the advantage of variable stator vanes?

A

a optimum angle of attack on the following rotor blades can be reached at every engine speed

58
Q

What is the disadvantage of a varable stator vane?

A

It needs a complicated control mechanism

59
Q

What are the 4 sub modules of the lp compressor and fan module?

A

Fan rotor and booster module
Number 1 and 2 bearing module
Inlet gear box
Fan frame module

60
Q

The spinner cone is also known as what?

A

Compressor inlet or nose cone

61
Q

What does the spinner cone do?

A

Covers end of fan rotor disc & creates a smooth aerodynamic fairing at engine inlet

62
Q

Where can weights be added to the spinner cone?

A

Mounting bolts or the threaded inserts

63
Q

What fitting is used to attach fan blades?

A

A dovetail fitting

64
Q

Why is a loose fit needed when mounting fan blades?

A

So any sudden forces or torque don’t exceed the allowable stress limits of the fan blades

65
Q

What are the 2 loads that act on the rotor blades?

A

Air loads
Centrifugal loads

66
Q

What do shrouds do?

A

Keep fan blade deflection within safe limits when heavy loads act on them.

67
Q

How do shrouds work?

A

By sliding contact surfaces of shrouds to convert fluctuating blade energy into friction energy to dampen blade friction.

68
Q

What type of fan blade is found on most modern GTE’s?

A

Wide chord fan blades.

69
Q

What are the advantages of a wide chord fan blade?

A

More efficient
Run at lower speeds
Very flexible
Withstand FOD better

70
Q

What is the LP compressor also called?

A

Booster module

71
Q

What is the rotor drum connected to in a LP compressor?

A

Fan disc

72
Q

The rotor drum has what sort of slots around its circumference?

A

Dove tail

73
Q
A
74
Q

What does the rotor drum hold and how?

A

The blades with a dovetail fitting

75
Q

How are the stator made up?

A

Either plain metal or individual segments

76
Q

The LP compressor case assembly does what?

A

Encloses the LP compressor rotor and supports the vanes of the LP compressor

77
Q

.

A

Vanes are fitted to shrouds between rotor stages

78
Q

What is the split stator case?

A

All vanes are installed in 2 stator halves and bolted together afterwards

79
Q

On modern turbo fan engine cases how many ring elements are there?

A

1 or more

80
Q

What do flanges do on the outer surface of a case?

A

Help to stiffen the case and prevent deformation

81
Q

What are acoustic panels?

A

Linings that reduce noise

82
Q

Why must you be careful with the outer surface of the acoustic lining?

A

It can be easily damaged with tools and FOD

83
Q

The outer guide vanes are installed where?

A

In the fan duct or behind the fan blades

84
Q

what is the purpose of the abradable shroud?

A

A soft material which prevents damage to fan blades if they come in contact with the shroud

85
Q

Why are the tips of the fan blades able to cut into the shroud?

A

So the blades can run with a very small tip clearance and max efficiency

86
Q

What is the purpose of the fan blade containment?

A

Prevents blade from penetrating fan case if it breaks

87
Q

Where is the fan frame located?

A

In between the LP and HP compressors

88
Q

What does the centre hub do?

A

Supports spool fwd bearing and houses internal gearbox

89
Q

What does the structure around the central hub do?

A

Diverts the air into the core

90
Q

What does the outer core of the fan frame give support to?

A

Engine equipment

91
Q

The fan frame strut connects what?

A

Internal and external section of the fan frame

92
Q

When does imbalance of a fan rotor occur?

A

If material is removed from a blade
Or
There’s a difference in weight of blades

93
Q

Moment of weight changes with what?

A

Blade mass
Position of CofG of fan blade

94
Q

Centrifugal force of the fan blade depends on what 3 things?

A

Rotor speed
Blade mass
Distance of CofG of fan blade from rotational axis

95
Q

Moment weight may be given in what?

A

Gram inches
Cmg
Oz inches

96
Q

A blade root will be marked with what?

A

Part number
Serial number
Moment weight

97
Q

What can you add to blades to get them balanced?

A

Balance weights

98
Q

What is the of set mounting hole used for?

A

To position the spinner cone in the correct position

99
Q

How is the disc rotor assembled on the HP compressor?

A

From individual discs and spacers

100
Q

How are rotor hubs in the HP compressor bolted?

A

With bolts or long tie rods

101
Q

What does the labyrinth seal prevent?

A

Reverse air flow through the gap between rotor and stator

102
Q

CDP?

A

Compressor discharge pressure

103
Q

CDP prevents what?

A

Compressor discharge airflow escaping into bearing area

104
Q

The HP compressor case of a turbofan is split up into what?

A

Front compressor case and rear compressor case

105
Q

What is the front compressor case made up of?

A

2 halves with a bolted centreline joint

106
Q

What does the front compressor case support?

A

Structural loads
(Bending and torsion)

107
Q

How are stator vanes usually installed?

A

In circumferential dovetail slots

108
Q

Why do the inner ends of the stator vane segments have a inner platform?

A

To minimise vibrations caused by the airflow

109
Q

Compressors with a high compression ratio have what?

A

Variable stator vanes

110
Q

Variable stator vanes have what at each end?

A

A trunnion

111
Q

Why do all variable stator vanes move simultaneously?

A

Because they are installed together with actuation leavers which are connected to a actuation ring

112
Q

Bleed air is supplied to the compressor via what?

A

Hollow stator vanes

M15 Ryan (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions