7 - Exhaust Flashcards
What does the exhasut system do to the gases
Gradually converts them to a solid flow of gases
How is the exhaust supported
Hollow struts or tie rods
What other purpose do radial struts perfrom
They help straighten swirling airflow
What is the purpose of the bellows in exhausts
Allows movement in installation, maintenance, and thermal expansion eliminating stress and warping
What are the two types of exhaust nozzles
- Converging
- Converging-diverging
What is the difference between ducted and unducted exhausts
Ducted exhausts have a common path for bypass and core
Unducted has two seperate parts
What does a converging exhaust do to
Increase gases velocity and therefore thrust by 15% - 20%
What does the divergent part of the exhaust do
Reduces turbulelnce
What does the convergent paart of the exhaust do
Increases velocity and therefore thrust
Why do soem aircraft use a convergent-divergent nozzle
To accelerate air to supersonic speeds
Why are thrust reversers used
To improve braking efficienccy on snowy/wet runways
How do thrust reversers slow the aircraft down
Blocker doors reverse the thrust
How does a clamshell reverser work
Actuators pivot internal doors that expose cascade vanes
How does a bucket type reverser work
Using hydarulics, two doors are placed behind the engine
How does fan reverser work
Translating sleeves within the nacelle redirect bypass (fan) airflow through cascade vanes
How does pivoting door reverser work
Sits flush with cowling until they are actviated. They move to block and redirect the bypass (fan) flow
Where does most noise from the engine come from
Exhaust
What causes the exhaust to be so loud
High velocity turbulent air
Why are turbojets louder than turbofan
Because they have a much higher exhaust gas velocity
