15.07 Flashcards
What does the exhaust system do?
Guides the exhaust gases
What does the exhaust do to airflow?
Accelerates it
What does the cone in the exhaust prevent?
Reverse flow
Where does the cold and hot air go in the exhaust?
Hot air to the primary nozzle and cold air to the secondary nozzle
What does mixing do and improve in the exhaust?
Improves mixing of hot and cold air to get higher propulsion efficiency
How do you achieve optimum thrust?
Gas must expand fully in the exhaust nozzle
What is the exhaust airflow caused by?
Pressure ratio between turbine discharge and ambient pressure
What ratio do convergent exhausts reach?
2:1
What does EPNdB stand for?
Effective perceived noise decibel
What are the two methods used to reduce noise levels of an engine?
Deigns and dampening internal and external noises
What do acoustic linings do?
Increase the weight but dampen noise a lot
On a wet, icy or snow covered runway what is reduced?
Braking
What are thrust reversers and what angle do they deploy at?
Reverse the flow of air and deploy at 45/60 degrees
Where are clamshell door type reversers used?
Older jet aircraft with a low bypass ratio
What type of thrust reverse door is used on modern aircraft?
Pivot door
What speed is thrust reverse most efficient at?
High speed
What does the reversed airflow have to be matched to?
The engine position
Why is thrust reverse design more important on 4 engine aircraft?
The reversed air can be ingested by the other engine
How is the flow out of the reverse thrusters altered?
Using the cascade vanes in the cowlings
What’s the control system used for?
To activate reverse thrust and change engine power
What is the reverser actuation system?
Moves airflow deflection mechanisms from signals from reverse control system
What do the airflow deflection devices do?
Change the direction of the air
What does the thrust reverse interlock ensure?
Engine power can only increase when reversers are fully deployed
Pneumatic reverser actuation systems are only used on what type of thrust reverser?
Cascade
What does reverse unlock message indicate?
Reverser is stowed but not safe
What does a green reverse light indicate?
Reverser is fully deployed and interlock is released
