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M15 GTE > Inlet > Flashcards

Inlet Flashcards

1
Q

How does air enter engine

A

Via intake

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2
Q

2 parts of an intake

A

Intake nose & inlet duct

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3
Q

What is a divergent

A

Shape when inlet duct gets wider

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4
Q

What does a divergent do

A

Increase static pressure of air moving through the duct

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5
Q

What does intake nose do

A

Smoothens airflow

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6
Q

Why does all air enter the inlet from the front

A

Ram air effect at high speeds

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7
Q

What velocity to the ensure flow through compressor is smooth

A

0.4-0.7 Mach

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8
Q

What is a intake designed to do and how

A

Decelerate flow & convert kinetic energy into pressure energy

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9
Q

How is a subsonic air inlet shaped

A

To deliver air to front of compressor which gives even pressure distribution

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10
Q

What’s the consequences of poor air pressure and velocity

A

Compressor stall

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11
Q

What happens to ram pressure as ram velocity increases

A

Decreases

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12
Q

What happens to air while the aircraft is stationary

A

Air in duct is accelerated to velocity required by compressor

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13
Q

What does a rounded inlet lip do

A

Gives it a thicker radius which reduces risk of separation

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14
Q

At high speed what shape inlet lip do we want

A

Thin

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15
Q

What is a transonic duct practical speed

A

Up to Mach 1.5

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16
Q

What does a transonic duct use to decelerate supersonic airflow

A

Shock diffuser

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17
Q

What happens in a normal shockwave

A

Pressure and temperature increases while velocity decreases to subsonic

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18
Q

What is critical condition

A

Cross section of the inlet is sufficient to allow max airflow requirements of the engine

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19
Q

What is sub critical

A

The shockwave is detached from the lip and moves upstream which reduces Mach number

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20
Q

What is super critical

A

The shockwave is swallowed which makes the airflow in the inlet become supersonic which is unacceptable flow into the compressor

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21
Q

What is diffuser buzz or intake buzz

A

When extreme pressure fluctuations can severely damage the engine

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22
Q

What happens to kinetic energy in a supersonic inlet duct

A

Large amount of it turns into unusable heat

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23
Q

What happens in a oblique shockwave

A

Forced to change direction , the shockwave is inclined at oblique angle which is determined by upstream velocity

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24
Q

Disadvantage of shock diffuser in supersonic duct

A

Abrupt loss of efficient as Mach number increases such as 30% at Mach 2

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25
Q

What does a oblique shock diffuser do

A

Reduces supersonic flow progressively by wing , in a series of oblique shock waves

26
Q

In a normal duct what will an inefficiency of 1% do

A

Thrust loss between 1% and 4%

27
Q

Efficiency of pilot design

A

96-99% efficient

28
Q

Efficiency of wing root design

A

87-95% efficient

29
Q

Efficiency of side design

A

80-89% efficient

30
Q

Efficiency of turbo prop annular (Dart)

A

74-82% efficient

31
Q

In a transonic duct what lip shape do you want

A

As thin as possible

32
Q

In a variable intake what’s the maximum amount of shockwaves

A

4 , 3 oblique 1 normal

33
Q

How can we prevent intake buzz

A

Bleed door

34
Q

How do we cool the engine bay

A

With Air bled from ramps used for engine bay cooling

35
Q

Problems with snow and ice

A

Cause turbulent flow which can stall

36
Q

What anti ice system is used

A

Jet engines have thermal anti - ice systems

37
Q

What are antennas heated with

A

Warm air

38
Q

What’s the purpose of anti ice valves

A

Protect against over pressurisation

39
Q

How are anti ice valves operated

A

Automatically via ice detection system or manually in flight deck

40
Q

What happens to the air used for anti-icing

A

Ejected over board via small grills

41
Q

What are the 2 methods of ice protection

A

Bleed air & electrical heating

42
Q

How is the thermal anti ice valve energised

A

Engine anti-ice switch/ light

43
Q

When does the amber light turn off

A

When LP sensor duct pressure is more then 5psi

44
Q

Where is duct over pressure signalled to

A

EICAS/ECAM

45
Q

Why is caution necessary when testing thermal anti Ice system on ground

A

Air is still hot no personnel should be in the area

46
Q

Where is electrical ice protection employed

A

Turbo prop engined aircraft

47
Q

Are mats supplied with AC or DC

A

Both

48
Q

What’s the purpose of the continuously heated element

A

Prevent formation of ice on leading edge or aircraft engine air intake lip and propeller spinners

49
Q

Where is a intermittently de-icing element located

A

Behind continuous heated element

50
Q

What type of system is a continuous heated element

A

Anti - icing

51
Q

What type of system is a intermittent heated element

A

De -icing

52
Q

In an intermittently heated element why are they divided into separate segments

A

To ensure ice breaks away easily

53
Q

What happens on the FAST cycle

A

ON/OFF for 2 minutes OAT between -6 & 10 degrees

54
Q

What is the SLOW cycle

A

ON/OFF for 6 minutes OAT below -6 degrees

55
Q

Why does the cycling light glow dim and bright

A

Indicate timer is rotating

56
Q

What is a heated mat examined for

A

Splits , tears , wrinkling and discolouration which happens due to overheating security of the attachment or general condition

57
Q

Where are anti-corrosion strips placed

A

Any sign of splitting or corrosion

58
Q

When should you replace a heated mat

A

any damage which exposes the heated element

59
Q

When does a continuity and resistance check need to be completed

A

Following any repair to heated mats , resistnace valves must be within limits

60
Q

Why do we need to do insulation resistance checks

A

To determine any breakdown of insulation between heater mats

Insulation resistance to earth must be checked

61
Q

What should

A

M15 GTE (19 decks)

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