15.10 lubrication systems Flashcards
(31 cards)
what are wet sump systems
stores oil in the engine
what is dry sump
stores oil in external tank mounted on or near engine
what are the two classifications of oil systems
full flow system
constant pressure system
what is the simplest type of oil supply system
full flow system
can the full flow oil system regulate the oil pressure?
no
what causes a change in oil pressure in a full flow system
rotor speed (n2)
oil temp
flow areas downstream
what drives supply pump in a full flow system
n2 rotor system via gearbox
where is the pressure relief valve located on a full flow system
between delivery and suction
what is constant pressure system called
regulated pressure system
how is oil pressure maintained in a constant pressure system
pressure regulating valve holds oil pressure to a given design value at all n2 rotor speeds
do changes in oil temp affect oil pressure in a constant pressure system?
no
pros of full flow system
simple
no adjustments are necessary
cons of full flow syste
needs a large supply pump or high oil pressure at idle
significant rise in oil temp after a power reduction
how can air cooling works
bleed air can be used to cool the turbine disk, vanes, blades etc
benefit of cooling air
reduce quantity of oil necessary to cool bearings
what is oil tank fabricated from
aluminium alloy coated with a layer of silicone
what are the two ways to fill oil tank
gravity
pressure
how are spills prevented in the oil tank
oil scupper
what prevents the discharge of air in the oil tank
check valve
why is pressure buildup desired in an oil tank
to ensure a positive flow of oil
what are the two most common oil pumps
gear pump
gearotor pump
what is the most commonly used oil pump used
gear pump
what are the two elements in a gear pumps
one for pressure oil
one for scavenge
how is air oil heat exchanger cooled
fan air
