Exhaust

Question 1

Main task of exhaust

Answer 1

Guide exhaust gas from rear of turbine into atmosphere

Question 2

What does the exhaust do in a jet engine

Answer 2

Exhaust system accelerates airflow from turbine to make thrust

Question 3

What does the apu do in exhaust

Answer 3

Guides exhaust gases overboard as all gas energy absorbed by the turbine

Question 4

What is the exhaust system tube called

Answer 4

Exhaust duct or tail pipe

Question 5

How is the conical tube supported

Answer 5

At its forward end by turbine exhaust

Question 6

Where is the exhaust nozzle and what does it do

Answer 6

Aft of the exhaust duct and accelerates gasses

Question 7

What does the exhaust cone do

Answer 7

Guides discharge flow and prevents excessive turbulence of the gases

Prevents reverse flow of exhaust gases into the hub of the turbine rear stage

Question 8

What’s the exhaust streams of a high bypass turbofan

Answer 8

Primary for hot gas

Secondary for cold air

Question 9

What aircraft are combined exhaust nozzle used for

Answer 9

Modern long range aircraft

Question 10

How does a combined exhaust nozzle work

Answer 10

Mixes gasses to reduce velocity

Question 11

Advantage to common exhaust nozzle

Answer 11

Reduces exhaust gas velocity which higher propolsion efficiency

Question 12

Disadvantage of common exhaust nozzle

Answer 12

Increases weight of engine

Question 13

What does the addition mixer do

Answer 13

Improves the mixing of hot and cold gas flow to get higher propulsion efficiency but also adds weight

Question 14

Why must exhaust gasses expand completely

Answer 14

To achieve optimum thrust from the given mass

Guarantees a laminar vortex-free and axially oriented exhaust gas flow

Question 15

When is a convergent exhaust nozzle used

Answer 15

For max airflow with a pressure ratio up to 2:1

Question 16

When is convergent divergent nozzle used

Answer 16

For pressure ratios bigger then 2:1 for aircraft’s to fly faster then speed of sound

Question 17

Why are high exhaust gas velocities avoided

Answer 17

Decrease the propulsion efficiency

Question 18

What unit is engine noise reduction

Answer 18

Effective Perceived Noise DeciBel EPNdB

Question 19

What variable is engine noise dependent on

Answer 19

Velocity of gases

Question 20

turbofan noise change depends on what ratio

Answer 20

Depending on bypass ratio

Question 21

How can we suppress noise

Answer 21

Reducing airflow disruption

Airflow lining are equipped with noise absorbing materials

Question 22

What is a porous surface made of and how does it minimise noise

Answer 22

Supported by honeycomb structures and converts sound energy into heat energy

Question 23

What are the two types of liner

Answer 23

Single and double

Question 24

How does a thrust reverser work

Answer 24

Producers a breaking force by deflecting exhaust gas stream to opposite direction

Question 25

Most ideal deflection angle

Answer 25

180 degrees but causes problems for engine

Question 26

What is the actual deflection angle

Answer 26

45-60 degrees

Question 27

What air is used for thrust reverser

Answer 27

Only Bypass air

Question 28

When are thrust reverses used

Answer 28

Only on ground

Question 29

How is the bucket on common thrust revereres operated

Answer 29

Hydraulically operated

Question 30

In a fan reverser what air is used

Answer 30

Cold fan is used which is secondary air

Question 31

What’s type of reverser is a fan reverser

Answer 31

Cascade type with translating sleeves

Question 32

How is a fan reverser operated

Answer 32

Pneumatically with drive motors Hydraulically with actuators

Question 33

How are pivot door reversers activated

Answer 33

Hydraulically

Question 34

How can you minimise the disadvantages of reverse thrust

Answer 34

March reverse airflow with engine position

Question 35

Why is angle of reverse steam important on 4 engine aircraft

Answer 35

Reverse airflow of the inner engines can be ingested by outer engines

Question 36

What’s the use of a cascade vane

Answer 36

Directs the airflow of a thrust reverser

Question 37

What advantage do large aircraft’s have in regards to thrust reversers

Answer 37

They use the same cowlings which means they can use less parts

Question 38

Can aircraft’s be released to service with faulty thrust reversers

Answer 38

Yes

Question 39

What does the control system do

Answer 39

Actives thrust reverser and increase engine power

Question 40

What components does a reverser actuation system have

Answer 40

Pneumatic or hydraulic

Question 41

What does the airflow deflection system do

Answer 41

Directs airflow in optimum direction for safe reverse thrust

Question 42

What does thrust reverser interlock do

Answer 42

Makes sure engine power can only be increased once reverser is deployed

Question 43

Where are hydraulic reverser actuation systems used

Answer 43

Reversers with translating sleeves and cascade vanes

Question 44

What does thrust reverser locking system do

Answer 44

Makes sure reverser is locked and stowed

Question 45

Where are blocker doors

Answer 45

Linked between the fixed cowl and translating sleeve

Question 46

What are 4 cascade airflow directions

Answer 46

45 degrees up 45 degrees down 90 degrees straight Some is blocked

Question 47

What does reverse unlock message indicate

Answer 47

Reverse is not safe in its stowed position

Question 48

What colour are reverse unlock messages

Answer 48

Amber & always shows when reverser moves from deployed to stowed

Question 49

When is the green reverse light show

Answer 49

Reverser fully deployed and throttle interlock is released so engine power can be increased for reverser thrust