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M15 New > 15.3 > Flashcards

15.3 Flashcards

1
Q

What does the inlet guide vane do

A

Straightens the airflow and direct it onto the first stages of the compressor

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2
Q

What’s the purpose of a screen on the engine

A

Prevent FOD

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3
Q

What is ram recovery or total pressure recovery and what does it do

A

The added pressure the inlet that increases pressure and airflow into engine

It compensates for loss of thrust due to increase in airspeed

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4
Q

What is the purpose of turning vanes

A

They are placed inside side-scoop inlet to straighten flow and prevent turbulence

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5
Q

What the 2 types of divided ducts

A

Wing root inlet or a scoop

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6
Q

Disadvantage of divided duct arrangement

A

Sudden manoeuvres provide an imbalance in ram pressure which can cause a slight loss in power

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7
Q

Function of an inlet duct

A

Provide correct amount of air into the engine inlet

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8
Q

In a variable geometry duct what must the engine airflow be

A

Below Mach 1

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9
Q

What do inlet ducts act as

A

Diffusers to decrease the velocity and increasing the static pressure

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10
Q

What makes a variable geometry duct VGD ‘variable’

A

Inside area of the configuration can be changed

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11
Q

How can you change the area of VGD

A

Introduce a restriction such as ramp or wedge in the duct

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12
Q

What does a variable airflow bypass arrangement do

A

Extracts part of the inlet airflow from the duct ahead of the engine

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13
Q

What’s the 3rd method to diffuse inlet air

A

Uses shockwaves into the airstream to decrease velocity of the airflow

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14
Q

What does a compressor inlet screen do

A

Prevent engine from ingesting items into the intake

Can be placed along the inlet duct

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15
Q

Disadvantage of compressor inlet screen

A

Loss of inlet duct pressure and subject to icing

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16
Q

Are screens used on the engines with titanium or steel fan blades

A

No , the disadvantages outweigh the advantages

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17
Q

When is a bell mouth compressor inlet used

A

During testing

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18
Q

What is duct loss considered as in bell mouth compressor inlet

A

0

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19
Q

How are turboprop inlets anti iced

A

Electrical elements in the lip opening of the intake

20
Q

Best arrangement for inlet design on turboprop

A

Ducted arrangement

21
Q

What’s the function of a conical spinner

A

Doesn’t allow ice build up on the surface

22
Q

On high bypass turbofan engines where is the fan constructed to

A

Forward end of the compressor

23
Q

What’s the function of the inlet cowl and where is it placed

A

Bolted to the front of the engine

Provides airflow path into engine

24
Q

What speed should the fan blades rotate to achieve the best efficiency

A

Low tip speed

25
Q

How does a fan reduce damage to engine

A

Throws fod radially outward and goes through fan discharge instead of engine

26
Q

2 ways of anti icing inlets

A

Warm bleed air from engines and conical spinner

27
Q

What 2 effects can ice have on the engine inlet

A

Reduce performance that can lead to compressor stall

Pieces of ice damage fan blades or inlet vanes

28
Q

What combination do inlets use to keep it free from ice

A

Warm oil from engine oil reservoir
&
hot air from compressor/diffuser

29
Q

When are heat strips used

A

Only when it’s just the cowl that needs anti-icing

30
Q

What conditions does ice form

A

5 degreess in dry air

7 degrees in moist air (fog and rainy)

31
Q

What engines is bleed air used on

A

Engines with high-mass airflow

32
Q

Where is bleed air bled from

A

Bled off the HP compressor

33
Q

What the function of anti-icing valves

A

Protect against over pressurisation to prevent loss of engine power

34
Q

Where are anti ice valve operated

A

Automatically via ice detection system or manually in flight deck

35
Q

How is air for the intake ejected overboard

A

Via small grills

36
Q

What happens to air used for the cone and inlet guide vanes

A

Directed overboard or back into LP compressor intake

37
Q

How are anti ice valves operated and selected

A

Selected electrically and pressure operated

38
Q

Low and high duct pressure and temperature causes what

A

Latched relay to be tripped and locks system out until reset

39
Q

What air does engine anti ice system use

A

Hot air from pneumatic system or directly from engine

40
Q

Precaution against the doing ground tests on thermal anti-ice system

A

No personnel should be in the test area during ground tests

41
Q

What’s the manual override function used for

A

Valve or system failure

42
Q

What does EEC do in terms of anti icing

A

Controls flow of hot air into the engine inlets

43
Q

What are electric heat strip systems constructed of

A

Electrical resistance wire embedded in layers of neoprene materials

44
Q

Where are heat strips located

A

Lip of nacelle

45
Q

What does an inlet guide vane do

A

Straighten airflow and direct it to the first stages of the compressor

M15 New (18 decks)

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