Brainscape's Knowledge GenomeTM

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


See full index

AT 103 > AT 103 Third Exam > Flashcards

AT 103 Third Exam Flashcards

1
Q

!! What are the advantages of a fuel injected system !!

A

Freedom from vaporization icing
more uniform delivery of air fuel mixture to each cylinder
improved control of fuel/air ratio
instant acceleration after idling with no tendency to stall
increased engine fuel efficiency and power

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

what is bendix

A

a servo

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

Difference between fuel injected and carburated

A

carburator - mixer
Fuel injected - meterer
fuel air mixture in fuel injected does not mix in the Venturi

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

carb vs injected similarity

A

both have an air inlet tube that goes through a Venturi
throttle regulates air through system

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

What does the idle valve do

A

connected to throttle linkage so that at idle, another part will open to let a little bit of fuel in in order to not over lean the mixture

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

What are the two functions of the fuel divider

A

ensures equal distribution of metered fuel to the nozzles
provides isolation of each nozzle for clean engine shutdown

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

What operates the fuel divider

A

fuel flow pressure

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

where does the air - fuel mixture meet?

A

right at the point before entering the cylinder

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

What are the two ways to produce thrust for turbine engines

A

aerodynamic action
jet reaction

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

How does aerodynamic action work

A

uses propellers
lift is produced along the horizontal plane
large mass of air through small change in velocity

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

how does jet reaction work

A

mass of air is heated inside the engine and discharged at high velocity through a shaped nozzle
Mass of air and amount determines thrust
(Small mass of air through large velocity change)

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

Who demonstrated the first jet propulsion (and when)

A

Heron of Alexandria
Egypt
first century AD

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

Quick turbine development history!

A

1232 Chinese weapon rockets
1872 Dr F Stolze first true gas turbine engine - never ran under own power
1939 - Ernst Heinkel Aircraft HE 178
1941 - Sir Frank Whittle designed Gloster Meteor
1942 - Messerschmitt Me 262 world’s first operational jet fighter

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

What is the Otto cycle

A

intake
compression
power
exhaust

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

What is the Brayton cycle

A

Otto cycle but with events occurring at the same time, however in different locations within engine

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

What happens in a convergent duct (supersonic)

A

air compresses
velocity decreases
pressure increases
density increases

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

What happens in a diverging duct (supersonic)

A

air expands
velocity increases
pressure decreases
density decreases

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

How does air flow through a chocked nozzle

A

velocity increases when converging, exhaust accelerates to speed of sound and forms shockwave creating pressure differential across nozzle that contributes to thrust

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

How does a non-air-breathing engine work

A

carries needed oxygen in fuel
generate heat by chemical reaction between fuel and oxidizer

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

how does turbojet work

A

takes in air
compresses
mixes compressed air with fuel
air fuel mixture ignited/burned
hot gasses pass through turbine
air forced out specially shaped exhaust nozzle

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

Benefits of the turbofan engine

A

increased propulsive efficiency
lower noise
lower fuel consumption

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

What does a bypass engine with a 4:1 ratio mean

A

(High bypass engine)

for every 4 molecules that enter, only one actually goes through the engine, the other three go into the bypass for cooling

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

What is thrust measured in

A

pounds

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

What is thrust determined by

A

change in momentum experienced by air flowing through the engine
momentum of the fuel
force caused by difference in pressure across the exhaust nozzle multiplied by the area of the nozzle

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

!! What is net thrust !!

A

thrust produced by the engine in flight

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

!! what is gross thrust !!

A

produced by the engine while engine is static and not moving ((test stand))

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

Thrust total =

A

thrust (core engine) + thrust (fan)

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

thrust indication for a small jet

A

% RPM

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

large jet engine indication

A

engine pressure ratio
(ratio of the turbine discharge total pressure to the compressor inlet total pressure)

30
Q

What is the inlet air duct

A

part responsible for supplying the constant, undisturbed flow of subsonic air to compressor
(usually considered part of the airframe)

31
Q

What are variable inlet ducts for

A

accommodate different air speeds by lowering/raising a wedge or moving a taper plug in or out of a duct

32
Q

Centrifugal compressors advantages

A

rugged
light weight
ease of construction
high pressure ratio for each stage

33
Q

what happens if a centrifugal compressor is too big

A

tip speed increases and efficiency decreases
difficult to streamline engine

34
Q

pros/cons of axial-flow compressor

A

heavy
costly
higher compression ratio
easier to streamline

35
Q

single spool axial flow compressor characteristics

A

limited stages
rearmost stages become inefficient/front stages become overloaded
airflow can become restricted and can lead to compressor surge

36
Q

In a dual spool axial flow compressor, which compressor starts the engine and why

A

N2 due to lighter weight

37
Q

compressors are made up of

A

rotor blades and fixed stator vanes which are shaped and positioned to form a series of divergent ducts

38
Q

Why do blades have a gap at idle

A

centrifugal force creates the seal as the engine speeds up

39
Q

where is the highest pressure point in the engine

A

diffuser section

40
Q

what is the diffuser section

A

diverging area for air to decrease velocity and increase pressure

41
Q

Advantages / Disadvantages of multi-can

A

A: individual cans can be removed
D: uneven temperatures which can cause turbine failure due to the extreme difference

42
Q

can-annular advantages

A

can remove cans
shorter cans with lower pressure drop
uniform temperatures even with a clogged fuel nozzle

43
Q

Pros / Cons of annular combusts

A

most efficient
minimum cooling
even temperature air

Cannot be replaced without removing engine

44
Q

What is the turbine section

A

power producing component of the engine

45
Q

Where is the hottest gas inside the turbine engine

A

turbine inlet guide vanes

46
Q

What is a reaction blade

A

produces force by aerodynamic action (airfoil)

47
Q

what is an impulse blade

A

produces turning force by the energy required to change the direction of airflow

48
Q

what is creep

A

deformation of metal that is continually under high centrifugal loads and temperatures

49
Q

what is metal fatigue

A

weakening of metal subjected to repeated cycles

50
Q

what is corrosion

A

electrolytic action that occurs when rallying agents combine with elements in the air to form salts

51
Q

Lubrication primary characteristics of turbine oil

A

Low Viscosity
High Film Strength (does not break under high pressure)
Low volatility (does not evaporate at low air pressures of high altitude)

52
Q

secondary characteristics of turbine oil

A

high flash point
low pour point
good anti-foaming
low carbon deposit

53
Q

what is the wet sump system

A

pressurized oil lubricates rotor coupling and bearings
accessory drive gears are splash lubricated

54
Q

dry sump system

A

after lubricating/cooling, oil is returned to tank by scavenger pumps

55
Q

Pressure subsystem

A

supplies correct amount of clean lubrication oil at the proper pressure and temperature

56
Q

scavenge subsystem

A

picks up oil after it has performed functions and returns oil to oil tank

57
Q

Vent subsystem

A

provides slight pressure on the oil in the oil tank to allow positive flow of oil

58
Q

where is oil usually filtered in a turbine engine

A

right after the pressure pump and again before being sprayed

59
Q

What is the chip detector

A

system that detects ferrous metal flakes or chips in the oil system
(canary in a coal mine)

60
Q

What is the oil pressure system reading

A

difference between pressure produced at the oil pump and the pressure of air in the vent system

61
Q

What is the difference between Jet A, A-1, B

A

Jet A: freezes at -40F
Jet A-1: freezes at -58F
Jet B: freezes at -60F

62
Q

Kerosene vs Avgas

A

K: 6.7 pounds per gallon
Av: “6” pounds per gallon
Kerosene has a lower heat energy per pound but higher per gallon

63
Q

What is the issue with turbine fuel viscosity

A

contaminants and water are suspended in jet fuel and take a long time to get picked up by the tank pumps

water can also freeze

64
Q

what do fuel nozzles do

A

vaporize fuel to mix with air

65
Q

if fuel flow is increased too quickly…

A

over rich mixture may result
excessive TIT or produces compressor surge
fire may go out

66
Q

if fuel flow is reduced too quickly

A

engine may experience lean die-out

67
Q

where is the TIT read

A

at the turbine inlet guide vanes

68
Q

What does FADEC do

A

controls all engine functions and eliminates need for backup hydro-mechanical control
controls engine power through direct control of EPR

69
Q

advantages of FADEC

A

no engine trimming required
improved engine starts
constant idle speed
saves fuel by improved engine bleed air management
fully modulates active tip clearance
automatically limits critical engine pressures and speeds, reducing wear and possible damage

70
Q

What happens if both channels fail

A

actuator motors are spring loaded to fail safe positions
fuel flow goes to minimum

71
Q

how does the turbine ignition system work

A

continuous combustion process so ignition is only needed during start

72
Q

what are the three different types of instrument gauges

A

temperature
pressure
mechanical movement

AT 103 (3 decks)

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