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AMT 225 > Turbine engine > Flashcards

Turbine engine Flashcards

1
Q

Four forces of flight?

A

Lift, weight, thrust, and drag

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2
Q

What is Newtons third law?

A

For every action there has to be an equal and opposite and reaction

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3
Q

What is thrust?

A

The forward directed force produced by the reaction from a rearward accelerated mass of air

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4
Q

What is the law of conservation of energy?

A

Energy can neither be created nor destroyed, but it can be changed from one form into another

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5
Q

What is potential energy?

A

Is the energy possessed by an object because of its position

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6
Q

What is kinetic energy?

A

Energy due to motion

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7
Q

What is Bernoulli’s principle?

A

The total energy in a column of moving fluid remains constant throughout the column

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8
Q

What type of air flows through a CD duct?

A

Subsonic

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9
Q

What is a convergent duct and what happens to the air as it passes?

A

The duct becomes smaller in the direction of flow. The air velocity increases and the pressure decreases

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10
Q

What is a divergent duct and what happens to the air as it flows?

A

The duct becomes larger in the direction of flow. The air velocity decreases and the pressure increases

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11
Q

What happens with supersonic flow through a converging duct?

A

Density increases, velocity decreases, pressure increases

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12
Q

What happens to supersonic flow through a diverging duct?

A

Density decreases, velocity increases, and its pressure decreases

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13
Q

What are the three types of pressure in a turbine engine?

A

Absolute
Gage
Differential

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14
Q

How is absolute pressure measured?

A

From zero or a vacuum

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15
Q

What is gauge pressure?

A

From existing atmospheric pressure

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16
Q

What is differential pressure?

A

The difference between two pressures

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17
Q

What are the two additional important pressures in turbine engines?

A

Static and total pressure

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18
Q

What are the basic components of a GTE?

A

Inlet
Compressor
Diffuser
Combustors
Turbine
Accessory gear box

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19
Q

What are the four types of GTE?

A

Turbojet
Turboprop
Turbofan
Turboshaft

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20
Q

How do you add more power to a turboprop?

A

Adding more turbine states or a free turbine to turn the propeller

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21
Q

What does a turbofan engine use for engine cooling?

A

By-pass air

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22
Q

What are the advantages of a turbofan over a turbojet?

A

Higher propulsive efficiency
Lower noise level
Lower specific fuel consumption

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23
Q

What is the bypass ratio?

A

The amount of air flow from the fan bypass to the core flow

24
Q

What is the engine pressure ratio?

A

The ratio of the turbine discharge total pressure to the compressor inlet total pressure

25
Q

What is EPR for?

A

To measure thrust on a GTE

26
Q

What are the two parameters used to measure engine thrust?

A

Percentage of RPM
EPR

27
Q

What is N1?

A

Low compressor speed

28
Q

What is N2

A

High compressor speed

29
Q

What are the factors affecting thrust?

A

Airspeed
Air temperature
Air pressure
Altitude
Ram effect

30
Q

What happens with air density and thrust as temp increases?

A

Air density and thrust decreases

31
Q

What happens with air density and thrust as pressure increases?

A

air density and thrust increase

32
Q

What happens to thrust as altitude increases?

A

Thrust decreases

33
Q

Why do jets fly at high altitudes?

A

Less drag
Engines need less power to move forward
More fuel efficient

34
Q

What are the two ways to increase thrust in a jet engine?

A

Water injection-increased mass airflow and low EGT

Afterburners-reheat the air after the turbine state

35
Q

The two kinds of air in a turbofan engine?

A

Core-used for combustion process to produce thrust

By-pass air- produces thrust and used for cooling

36
Q

What is a free-turbine engine?

A

An engine that uses a separate turbine to drive the propeller in a turboprop or fan in a turbo fan

37
Q

What are the components of the cold section?

A

Inlet
Compressor
Diffuser

38
Q

What is a station designation?

A

Where along the length of the engine a component is located

39
Q

How does inlet anti-icing work?

A

Warm air is bled from the engine’s compressor and is ducted through the inlet

40
Q

What must supersonic aircraft use CD inlet ducts?

A

To slow the air to subsonic speeds

41
Q

What is a compressor?

A

To supply the correct amount of air for the fuel and to supply it with correct pressure and velocity

42
Q

What is a secondary function of a compressor?

A

To supply bleed air for various purposes in the engine and aircraft

43
Q

What are the types of compressors?

A

Centrifugal
Axial flow
Hybrid

44
Q

What are the components of a centrifugal compressor?

A

Impeller-rotating part
Diffuser-captures the air and forms divergent ducts
Manifold-collects air and directs it toward the combustion chamber

45
Q

What are the two components of a axial flow compressor?

A

Rotor blades-spun by axle powered by the turbine

Stator vanes-do not spin

46
Q

What is the purpose of inlet guide vanes?

A

Changes the direction of the airflow so that it hits the first stage rotors at the optimum angle

47
Q

Why are stator vanes behind rotor vanes?

A

To form a series of divergent ducts converting velocity to pressure

48
Q

Each consecutive pair of rotor and stator blades constitutes what?

A

A pressure stage

49
Q

What is compression ratio?

A

Compressor discharge pressure/compressor inlet pressure

50
Q

What is a blade stall?

A

The blade AOA becomes excessive, blades stall and airflow separates

51
Q

What design features prevent compressor stall?

A

Surge bleed valves
Variable stator vanes
Multiple spools

52
Q

What are surge bleed valves?

A

Dump pressure from the last sages of the compressor to increase airflow

53
Q

What are variable stator vanes?

A

Repositions the stator vanes to optimize rotor blade AOA

54
Q

Multiple spools

A

Each spool operates at its optimum speed

55
Q

What is a 2-spool engine?

A

An engine with two separate compressors each driven by its own turbine section

56
Q

What is a mid-span shroud?

A

Provides stiffness and to prevent flutter

57
Q

Where is the highest pressure located in an engine?

A

At the diffusor

AMT 225 (8 decks)

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