15.3 inlet Flashcards
what do many engines use to straighten the relative airflow and direct it into the first stages of the compressor
inlet guide vanes
what can the inefficiencies of the inlet duct result in
performance losses through other components
what do many turboprops and turboshaft engines have to protect against FOD
screens
when an aircraft reaches a certain point, what compensates for the losses caused by the increases in speed
Ram recovery
what is an air pressure drop in the engine inlet caused by
friction of air along both sides of the duct and by the bends in the duct system
what do turboprops use to provide anti-icing
warm oil from the engine oil
what are the two sub-sections of thermal ice protection
bleed air
electrical heating
where is hot air taken from for bleed air anti icing
it is bleed off from the engine HP compressor
what do small turboprops and turboshaft engines tend to use for anti-icing
electrical heating strips
what is the anti-icing valve used to protect against
over pressurisation and limit the bleed of air from the engine
where are solenoid-controlled pressure regulating valves found
in the engine anti-ice system
what controls the flow of hot air to the engine inlet based on input from the aircraft and engine sensor
the EEC
what can divided ducts be either
a wing root inlet or a scoop at each side of the fuselage
what is the major drawback of divided ducts
designing an entrance duct of reasonable length with few bends as possible
what is sometime placed in the side scoop inlet of a divided duct to assist in straightening the incoming airflow and prevent turbulence
a series of turning vanes
what another disadvantage of divided ducts
sudden flight manoeuvres can cause an imbalance in ram air pressure
what is used to achieve air reduction through the duct before the airflow enters the compressor
inlet ducts designed as diffusers
what ducts do very high speed aircraft use
variable geometry inlet duct
what are the three methods to diffuse the inlet air and slow the inlet airflow
- vary the area, or geometry, of the inlet duct
- use a variable airflow bypass
- the use of a shock wave in the airstream
what produces larger changes in the properties of the air or gas
stronger shock wave .
when are bell mouth inlets usually installed
they are installed on an engine undergoing testing in a test cell
why are the air inlets on a turboprop more of a problem than some gas turbines
because the propeller drive shaft, the hub, and the spinner must be considered
what is considered the best inlet design for turboprop engines
the ducting arrangement
