Tasks of oil on engines
Lubricate
Cool
Clean
Corrosion protection
2 groups of engine oil
Synthetic and mineral
Types of synthetic oil
Type 1- older engine
2- modern GTE
3- special aircraft - eurofighter
What is viscosity
Internal resistance of a fluid against deformation
What does viscosity depend on
Temperature of oil
High at low temp, low at high temp
What is viscosity index
Effect temperature has on viscosity of oil. Higher number = less effects
What is pour point
Lowest temperature that oil moves in a 31.75mm tube held horizontally for 5 seconds
What is type 2 pour point
-57 C
What is flash point
Lowest temperature that the oil gives off enough vapour to flash when flame is applied. Should be as high as possible
What is type 2 flash point
250 C +
What is oxidisation resistance
Reaction between oil and oxygen which makes it thicker and increases velocity
What is acidity
Measure of corrosive tendencies
What is thermal stability
Oil resistance to decomposition of oil compounds at high temps
What is votality
Measure of which a liquid is converted into a vapour
Factors affecting performance of oil
Oil foam, rubber swell, pressure, coking
What is oil foaming
Measure of resistance of oil from entrapped air
What is coking
Amount of carbon residue remaining in oil after heating
What is foam resistance
Collection of small bubbles near surface which leads to oxidisation, cavitation and failures
What is separation of oil from water called
Demulsibility
What are turbine engine fuels
Kerosene fuel
What is kerosene fuel manufactured from
Crude oil petroleum
Fuel composition
16% hydrogen, 84% carbon and impurities
4 types of turbine fuel
Jet A1, A, B and JP5
What is Jet A1
Most used in Europe,
JP1A in America
