Module 6: Diffusers and Combustion Section Review

Question 1

This area has the highest static pressure and potential energy and is the DIVERGENT section of the engine

Answer 1

Diffuser

Question 2

What is the purpose of a diffuser?

Answer 2

reduce velocity, increase pressure for combustion

Question 3

This area has the largest kinetic energy due to an ignition of high pressure mixed with fuel

Answer 3

Combustion exhaust

Question 4

What is the purpose of the combustion chamber?

Answer 4

turn the turbine

generate propulsion

Question 5

An effective combustion chamber must provide what?

Answer 5

fuel/air mix
efficient mix burn
cooling to tolerable temp
hot gas evenly distributed to turbine

Question 6

What are the components of the combustion chamber?

Answer 6

Case
Inner Liner
fuel drain
fuel injection/nozzle
ignition

Question 7

What serves as a cooling jacket and delivers high pressure air to the inner liner?

Answer 7

Casing

Question 8

What is the inner liner?

Answer 8

chamber of fuel/air mix burn

holes for combustion and cooling

Question 9

This component injects atomized fuel into the inner liner

Answer 9

Fuel Nozzles

Question 10

What are the igniters?

Answer 10

provides initial ignition

Question 11

This component is located at the lowest part?

Answer 11

Fuel Drain

Question 12

What is purpose of the primary air stream?

Answer 12

directed into the front of inner liner to mix with fuel for combustion

Question 13

this type of air passes through the outer casing via holes in the liner to prevent combustion gases from contacting the inside wall of the inner liner

Answer 13

secondary air

Question 14

In modern engines, what % of discharge is primary airflow and what % is for cooling?

Answer 14

45% primary

55% cooling

Question 15

What is the purpose of louvers and cooling holes?

Answer 15

prevents the burning of inner liner walls by directing cooling air

Question 16

This part dilutes the hot gasses prior to going to the turbine

Answer 16

Dilution Holes

Question 17

What are the 2 functions of pre-swirl vanes?

Answer 17

swirl air to reduce velocity

swirl fuel for atomization

Question 18

What is the #1 cause of engine flameout?

Answer 18

excessively high/slow airflowrates

Question 19

What are 2 types of Flameout?

Answer 19

Lean die out

Rich blowout

Question 20

This type of flameout ually occurs at high altitude with low engine speeds & low fuel pressure, resulting in a weak flame that can extinguish with normal airflow

Answer 20

Lean die out

Question 21

Describe rich blowout?

Answer 21

Rich mixture
low airflow
low fuel temp
rapid acceleration

Question 22

What are the types of combustion chambers?

Answer 22

Single Burner
Multi Can
Annular
Can Annular

Question 23

What is the purpose of Flame Propagation tubes?

Answer 23

To make sure the combustion is even and provides a path

Question 24

This type of combustor is also known as the BASKET type and consists of what?

Answer 24

Annular, consists on inner and out liners

Question 25

What are 2 types of Annular Combustors?

Answer 25

Straight flow

Reverse Flow

Question 26

How does a straight flow combustor work?

Answer 26

Air enters front discharged at rear

Question 27

What is the most efficient design?

Answer 27

Straight Flow Annular

Question 28

This type is mostly used by turboprop and helicopters

Answer 28

Reverse flow Annular

Question 29

How does the reverse flow annular work?

Answer 29

Reverses the direction of airflow 180 degrees twice

Question 30

This type of combustor is the easiest to maintain due to the fact that each can be removed as a single unit

Answer 30

Can Annular

Question 31

What can drain residual combustion fuel, after shutdown, to prevent a subsequent hot start or tailpipe fires?

Answer 31

Fuel Drain Valve

Question 32

A fuel drain valve can prevent what?

Answer 32

Hot start

Tailpipe fires