Turbine Hot Section Flashcards

1
Q

The hot section comprises of?

A

Combustion section
Turbines
Exhaust

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2
Q

Primary vs secondary air

A

Primary air is used for combustion
Secondary air is used for cooling

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3
Q

What are the 4 types of combustor designs?

A

Can
Can-annular
Annular
Reverse-flow annular

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4
Q

What is the main purpose of a turbine?

A

To drive the compress or propeller/fan

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5
Q

How do you extract more power from a turbine?

A

add turbine stages

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6
Q

Where is the temperature of gases the highest?

A

As they enter the first stage of turbine

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7
Q

Where is the highest velocity of a turbine?

A

As they leave the turbine

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8
Q

What are stator blades?

A

Fixed blades to direct the air so it will enter the turbine blades at the optimum angle.
Also decrease pressure and increase velocity

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9
Q

What the most common way turbine blades are attached?

A

Fir-tree method

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10
Q

What are the three types of turbine blades?

A

Impulse
Reaction
Impulse-reaction

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11
Q

What are impulse blades?

A

Shaped like buckets
No change in velocity

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12
Q

What are reaction blades?

A

Shaped like airfoils
Increase velocity

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13
Q

Types of turbine failures?

A

Creep
Metal fatigue
Corrosion

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14
Q

What is creep?

A

Deformation of metal due to continuous centrifugal loads and high temperatures

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15
Q

What is metal fatigue?

A

Due to repeated cyclic loading

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16
Q

What is corrosion?

A

Accelerated by high temperature

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17
Q

What are the two ways of driving accessory systems?

A

Using compressor bleed air

Driven by the compressor drive shaft through gears

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18
Q

What type of engine is an APU

A

Turboshaft

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19
Q

What is the purpose of a APU?

A

A device that provides energy for functions other than propulsion

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20
Q

How does an APU work?

A

It drives a generator, that may provide pressurized bleed air for ground heating and cooling the cabin, may supply an an auxiliary hydraulic system

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21
Q

What is the function of an APU?

A

Electric power
Pneumatic power
Hydraulic pressure

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22
Q

Why is the hot section subjected to more severe stresses?

A

Its subjected to high temperature exposure

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23
Q

Where is the location of the combustion section?

A

Between the diffuser and turbine section

24
Q

What is the primary function of the combustion section?

A

To burn the fuel/air mixture

25
Q

What components are located in the combustion section?

A

Fuel nozzles
Igniters
Shrouding
Cooling shrouds and ducts
Fuel drainage system

26
Q

What are the pros and cons of a can type combustor?

A

Pro-can remove individual cans for inspection
Cons-uneven temp distribution to turbine if one can fails

27
Q

Advantages of can-annular combustors?

A

Possible to remove individual cans for inspection

Event temp distribution even if on can fails

28
Q

What is an annular combustor?

A

One combustion chamber extending all the way around the outside of the turbine shaft housing

29
Q

Pros and cons of annular combustor?

A

Pro-Limited space required, minimum amount of cooling required, even temp distribution

Con-engine has to be removed to replace it

30
Q

When are reverse-flow combustors used?

A

Where engine length is critical

31
Q

What is the function of the turbine section?

A

Transforms the energy of exhaust gases into mechanical energy to drive the compressors and accessories

32
Q

Turbine strators create what type of ducts?

A

Convergent ducts

33
Q

Compressor stators create what type of ducts?

A

divergent ducts

34
Q

Does the gearbox connect to the low-pressure or hi-pressure side of a turbine engine?

A

hi pressure side

35
Q

The accessory section of a turbine engine drives what components?

A

Hydraulic pumps
Air conditioning units
Actuators
Oil pumps
Generators

36
Q

What is a gear train?

A

A series of two or more meshed gears used to increase or decrease the RPM, torque, or direction of rotation of the output gear

37
Q

What are the three type of gear types?

A

Parallel
Intersecting
Non-intersecting and non-parallel (worm gear)

38
Q

What is the purpose of an oil-damping bearing?

A

To compensate for slight misalignment and absorb vibrations of the shaft

39
Q

What are the two common types of seals used on jet engines?

A

Carbon seals
Labyrinth seals

40
Q

Carbon seals are what type of seals?

A

Rubbing-type seals used when absolute minimum leakage can be allowed

Contact is maintained between the stationary carbon element and a polished steel surface

Extremely brittle

41
Q

Labyrinth seals are what type of seals?

A

non-rubbing seals-rotating portion of the seal does not perform sealing action by pressing against the race

Depends on air pressure to perform sealing action

42
Q

What type of power does an APU provide to start the main engines?

A

pneumatic power

43
Q

What information is on a data plate?

A

It confirms the engine part no, serial no, manufacturer, type, weight, oil quantity

44
Q

What would you use to inspect the inside of an engine without disassembly?

A

A borescope

45
Q

How do you mark a component in the hot section?

A

Layout dye or chalk

46
Q

Three different kinds of bearing loads

A

Radial
Thrust or Axial
Combination

47
Q

Radial load are exerted?

A

Perpendicular to the shaft

48
Q

Thrust or axial load are exerted?

A

Parallel to the shaft

49
Q

Combination loads are exerted?

A

Both radial and axial

50
Q

Three types of bearings?

A

Ball
Roller
Tapered

51
Q

Ball bearings can take what type of loads?

A

Radial and thrust

52
Q

Roller bearings support?

A

Radial loads

53
Q

Roller bearings cannot handle?

A

thrust loads

54
Q

Tapered roller bearings are designed to support?

A

Large radial and thrust loads

55
Q

The turbine/compressor shaft is supported by what type of bearings?

A

roller and/or ball