Turbine Hot Section

Question 1

The hot section comprises of?

Answer 1

Combustion section
Turbines
Exhaust

Question 2

Primary vs secondary air

Answer 2

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

Question 3

What are the 4 types of combustor designs?

Answer 3

Can
Can-annular
Annular
Reverse-flow annular

Question 4

What is the main purpose of a turbine?

Answer 4

To drive the compress or propeller/fan

Question 5

How do you extract more power from a turbine?

Answer 5

add turbine stages

Question 6

Where is the temperature of gases the highest?

Answer 6

As they enter the first stage of turbine

Question 7

Where is the highest velocity of a turbine?

Answer 7

As they leave the turbine

Question 8

What are stator blades?

Answer 8

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

Question 9

What the most common way turbine blades are attached?

Answer 9

Fir-tree method

Question 10

What are the three types of turbine blades?

Answer 10

Impulse
Reaction
Impulse-reaction

Question 11

What are impulse blades?

Answer 11

Shaped like buckets
No change in velocity

Question 12

What are reaction blades?

Answer 12

Shaped like airfoils
Increase velocity

Question 13

Types of turbine failures?

Answer 13

Creep
Metal fatigue
Corrosion

Question 14

What is creep?

Answer 14

Deformation of metal due to continuous centrifugal loads and high temperatures

Question 15

What is metal fatigue?

Answer 15

Due to repeated cyclic loading

Question 16

What is corrosion?

Answer 16

Accelerated by high temperature

Question 17

What are the two ways of driving accessory systems?

Answer 17

Using compressor bleed air

Driven by the compressor drive shaft through gears

Question 18

What type of engine is an APU

Answer 18

Turboshaft

Question 19

What is the purpose of a APU?

Answer 19

A device that provides energy for functions other than propulsion

Question 20

How does an APU work?

Answer 20

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

Question 21

What is the function of an APU?

Answer 21

Electric power
Pneumatic power
Hydraulic pressure

Question 22

Why is the hot section subjected to more severe stresses?

Answer 22

Its subjected to high temperature exposure

Question 23

Where is the location of the combustion section?

Answer 23

Between the diffuser and turbine section

Question 24

What is the primary function of the combustion section?

Answer 24

To burn the fuel/air mixture

Question 25

What components are located in the combustion section?

Answer 25

Fuel nozzles Igniters Shrouding Cooling shrouds and ducts Fuel drainage system

Question 26

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

Answer 26

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

Question 27

Advantages of can-annular combustors?

Answer 27

Possible to remove individual cans for inspection Event temp distribution even if on can fails

Question 28

What is an annular combustor?

Answer 28

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

Question 29

Pros and cons of annular combustor?

Answer 29

Pro-Limited space required, minimum amount of cooling required, even temp distribution Con-engine has to be removed to replace it

Question 30

When are reverse-flow combustors used?

Answer 30

Where engine length is critical

Question 31

What is the function of the turbine section?

Answer 31

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

Question 32

Turbine strators create what type of ducts?

Answer 32

Convergent ducts

Question 33

Compressor stators create what type of ducts?

Answer 33

divergent ducts

Question 34

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

Answer 34

hi pressure side

Question 35

The accessory section of a turbine engine drives what components?

Answer 35

Hydraulic pumps Air conditioning units Actuators Oil pumps Generators

Question 36

What is a gear train?

Answer 36

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

Question 37

What are the three type of gear types?

Answer 37

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

Question 38

What is the purpose of an oil-damping bearing?

Answer 38

To compensate for slight misalignment and absorb vibrations of the shaft

Question 39

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

Answer 39

Carbon seals Labyrinth seals

Question 40

Carbon seals are what type of seals?

Answer 40

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

Question 41

Labyrinth seals are what type of seals?

Answer 41

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

Question 42

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

Answer 42

pneumatic power

Question 43

What information is on a data plate?

Answer 43

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

Question 44

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

Answer 44

A borescope

Question 45

How do you mark a component in the hot section?

Answer 45

Layout dye or chalk

Question 46

Three different kinds of bearing loads

Answer 46

Radial Thrust or Axial Combination

Question 47

Radial load are exerted?

Answer 47

Perpendicular to the shaft

Question 48

Thrust or axial load are exerted?

Answer 48

Parallel to the shaft

Question 49

Combination loads are exerted?

Answer 49

Both radial and axial

Question 50

Three types of bearings?

Answer 50

Ball Roller Tapered

Question 51

Ball bearings can take what type of loads?

Answer 51

Radial and thrust

Question 52

Roller bearings support?

Answer 52

Radial loads

Question 53

Roller bearings cannot handle?

Answer 53

thrust loads

Question 54

Tapered roller bearings are designed to support?

Answer 54

Large radial and thrust loads

Question 55

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

Answer 55

roller and/or ball