In gas turbine engines and jet engines what kind of an oil lubrication system do they use??

Answer 1

If you check my answer to your other post about bearings, you'll find more info there. I've worked on several types of jet engines, and although each one has very specific designs and systems, all are essentially the same.

The bearings are contained in a sealed compartment called a "sump". Each end of the sump is sealed with labyrinth type carbon seals and O-rings. Sealing is accomplished with physical force by springs within the seals and also by high pressure air from the compressor.

High pressure pumps circulate pressurized oil via steel tubing throughout the engine, to each sump area, as well as removing it from the sump areas and passing it through filters and coolers. It is then stored in a separate, external tank before being used again.

Nozzles, located within the sumps, actually spray oil on the bearings. In effect, the bearings are actually bathed in oil, but they do not sit in a static pool of oil like in an automobile engine. They are not a "sealed" type of bearings that are packed with grease, such as in a wheel bearing. In fact, the bearings are reused during engine rebuilds. They are inspected and if wear is within normal limits, they can be reused. The oil itself can actually be an indicator of engine health between rebuilds. A sample is taken and run through a spectral analyzer to look for excessive metals that would indicate abnormal wear of the bearings and/or shaft.

The lubricating system is quite complex and is designed to provide a positive flow of oil at all flight attitudes, including inverted. The lubricating system provides lubrication, cleaning and cooling to the bearings.

I'm not familiar with "air bearings" although I have seen some info about that type of system. I don't know it is being used in commercial or military application.

Answer 2

Gas Turbine Engine Lubrication System

Answer 3

They use a dry-sump system.

An oil tank holds the oil and a pressure pump feeds the oil to the bearings. Scavenge pumps (usually several, sometimes located right at the bearings or with the pressure pump) return the oil from the bearings to the oil tank. An air-oil or fuel-oil cooler is usually located somewhere in the loop.

Since the bearings are located centrally and surrounded by the air inlet/compressor/combustion chamber and turbine, they need to be sealed to prevent oil leaking throughout the engine. Conventional shaft seal will not work at the high temperatures and RPMs of turbine engines so labyrinth seals are used. They include stationary and rotating channels (forming a 'labyrinth') between the shaft and the bearing boss and is sealed with bleed air from the compressor.

Answer 4

I believe its a wet sump system of some sort. I haven't learned them yet and my books are at school. The bearings are roller type, and the oil is kept from leaving the bearing using bleed air from the compressor side of the engine. The air creates a barrier that the oil wont pass through. There's still a rubber seal, its just got pressurized air on the other side. I believe that's how the new style is, I don't know about the old style, must have just been a seal. All I know for sure is no matter what, they burn oil, and the oil is always full synthetic.

Answer 5

Jet and turbine engines have a lubrication system much like your car's engine, the main difference being that most cars have a wet sump system (the oil is stored in the oil pan below the block) where as the jet or turbine has a dry sump system (oil is stored in a separate tank).

Because they have a dry sump system, they also have two oil pumps... the main pump to pump oil from the tank into the pressurized oil galleries/oil lines and a scavenge pump to pump any excess/drained down oil back to the oil tank.

In addition, all of them have an oil cooler for obvious reasons and most have an accumulator to maintain pressure when the pick-up in the tank is not submerged, i.e. when the aircraft is flying inverted. (Sorry, I spent 23 years working on fighter aircraft.)

Answer 6

Maybe what is being asked , is what holds the compressor shaft to the turbine shaft. They are splined together where the shaft passes through the combustion section. Once the splines are fully engaged, a locking device is engaged so the splines cannot disengage. There has to some slight room for movement in this coupling as during engine operation there is both positive and negative thrust applied to the coupling shaft. CJ1pluspilot - bearings support shafts, they do not connect them.

Answer 7

I'm sorry that I'm not an expert with jet aviation (ask me something about pre-WW I and WW I and I can answer firmly, but jets? My guess is that their bearings are factory sealed. Jets burn a diesel fuel known as JP, and then there are various grades such as: JP-4, JP-5, etc.. My guess would be the only working parts on an axial flow turbine would be the shaft and that those bearings as I said, would be factory sealed. Can't be oiled...

Answer 8

the only moving part is the rotor with the turbine blades. I saw a turbine engine that had air bearings, no oil. the rotor was put under very high pressure and levitated, kinda like an air hockey table works.

Answer 9

Positive pressure system to the bearings

Answer 10

Interesting question