15.3 Inlets Flashcards
What is an inlet guide vane?
A device designed to straighten airflow and direct it into the compressor
What is the inlet of the nacelle considered to be a component of?
The airframe
What are the characteristics of a divergent duct?
-velocity decreases
-pressure increases
-temperature increases
What are the characteristics of a convergent duct?
-Velocity increases
-pressure decrease
-temperature decrease
What is important regarding supersonic airflow through ducts?
The characteristics switch
What do the inlets of turbo prop and turbo shaft engines that jet and fan do not?
Screens
What are the characteristics of a divided entry duct?
-Typically wing root or air scoop on fuselage
-they supply air to one or more engines
-one difficulty is having minimal bends with reasonable inlet length
-some manoeuvres limit RAM air and cause a loss in power
What are the characteristics of inlet ducts?
-typically a supersonic inlet will have a sharp lip
-the role of the duct is to decrease airflow to subsonic speeds
-they cause a normal shockwave at the entrance
What are the characteristics of a variable geometry duct?
-Uses a mechanical device to alter airflow into the engine
-either through extracting airflow before it reaches the engine using a ramp, wedge or use of a shockwave.
What is the use of a compressor inlet screen?
prevent FOD ingestion
What are the drawbacks of a compressor inlet screen? And how can they be overcome?
-ice build up
-loss in inlet duct pressure
-can be prone to mechanical failure
They can be retractable
What is a bell mouth compressor inlet?
-used in testing often equipped with probes
-duct loss can be considered zero
What is the common type of inlet for turboshaft and turbo prop?
-ducted arrangement
-sometimes using deflector doors to direct FOD
How are turbofan engine inlets deiced?
Bleed air is used from the compressor
How is FOD delt with in a turbo fan engine?
It is projected outwards into bypass air
