Presentation is loading. Please wait.

Presentation is loading. Please wait.

JET PROPULSION Part 5 Jet Engine Operation Oil Systems.

Similar presentations


Presentation on theme: "JET PROPULSION Part 5 Jet Engine Operation Oil Systems."— Presentation transcript:

1 JET PROPULSION Part 5 Jet Engine Operation Oil Systems

2 Introduction Early jet engines had a ‘Total Loss’ oil system, that is oil was taken from the tank, used for lubrication and was then lost overboard. Now, jet engines have what is known as ‘Dry Sump, Recirculating System’ In jet engines oil is sucked (scavenged) out of the sump and returned to a separate tank. The scavenge pumps have a greater capacity than is required to make sure that all the oil is actually taken out of the sump, hence the term ‘dry’ sump.

3 Engine Bearing Chamber Dry Sump Recirculating System Tank Pump Filter i.e. oil was lost in the gas stream Early jet engines were a total loss system SUMP Scavenge Pump Scavenge pumps make sure all the oil is actually taken out of the sump, hence the term ‘DRY-SUMP’.

4 Engine Bearing Chamber Dry Sump Recirculating System Tank Pump Filter Early jet engines were a total loss system Oil scavenged from the engine, is replaced in the tank ready to be used again, hence the term ‘RECIRCULATING’. SUMP Scavenge Pump

5 Oil Systems Typical Oil System SUPPORT BEARINGS As we know, location bearings support the engine rotor, which have to be lubricated to maintain smooth operation. These bearings are contained within bearing chambers; the number of bearings inside a chamber can vary with different designs of jet engines.

6 Oil Systems Typical Oil System PRESSURE OIL PUMP ASSEMBLY OIL COOLER Oil is sucked out of the tank by the pressure pump, which then forces it through an oil cooler. Coolers are placed before the tank, a ‘Cool Tank system’ or after, a ‘Hot Tank system’. OIL TANK

7 Oil Systems Typical Oil System PRESSURE OIL PUMP ASSEMBLY OIL COOLER Oil flows via individual pipes, to the bearing chambers. Oil distribution is set to the correct flow because bearings near hotter engine parts require the greater oil flow for cooling as well as lubrication. OIL TANK

8 Oil Systems Typical Oil System SCAVENGE PRESSURE OIL PUMP ASSEMBLY OIL COOLER Each chamber is scavenged by its own pump ensuring no oil rests in the bearing chamber sump. The outlet from the scavenge pumps is combined to a single return flow back to the oil tank. OIL TANK

9 Oil Systems Typical Oil System SCAVENGE PRESSURE OIL PUMP ASSEMBLY MCD MASTER MCD MCD OIL COOLER If a bearing starts to disintegrate, it generates particles. As bearings are made from magnetic metals, magnets are fitted into the scavenge system called Magnetic Chip Detectors (MCD’s). OIL TANK

10 The Bearing Chamber Bearing Oil Supply and Scavenge Let’s take a closer look at what happens here

11 The Bearing Chamber Bearing Oil Supply and Scavenge Shaft Oil Jet Oil Supply The oil is delivered under pressure to a jet. Once the oil has passed through the jet, its pressure becomes the same as the bearing chamber pressure.

12 The Bearing Chamber Bearing Oil Supply and Scavenge Shaft Oil Jet Oil Supply The jet is directed to a rotating reservoir, filling by centrifugal force when the engine is running. The oil evens out providing a feed through internal drillings to all areas of the bearings.

13 The Bearing Chamber Bearing Oil Supply and Scavenge Shaft Oil Jet Oil Supply Scavenge Oil to tank After the oil has lubricated the bearing, it drops to the bottom of the bearing chamber sump, it drops to the bottom of the bearing chamber sump, and is taken away by the scavenge pumps and returned to the oil tank.

14 The Bearing Chamber Bearing Oil Supply and Scavenge Shaft Oil Jet Oil Supply In order to prevent the loss of oil, the bearing chambers need to be sealed, allowing the oil to be continuously recirculated through the system. Scavenge Oil to tank

15 The Bearing Chamber Bearing Oil Supply and Scavenge Shaft Oil Jet Oil Supply As the bearings are situated between the rotating and static parts of the engine, the seals cannot be of contact type, so air sealing vents are added. Scavenge Oil to tank

16 The Bearing Chamber Bearing Oil Supply and Scavenge Shaft Pressurised air from compressors Higher pressure air forced into the Bearing Chamber prevents oil loss Oil Jet Oil Supply The seals basically comprise of a small gap between the rotating and static part of the engine, to which an air pressure is applied from the outside. Scavenge Oil to tank

17 Oil Systems Oil System with Air Sealing Returning oil passes through an air/oil separator :- A Settlement tray allows air to bubble to the oil surface A Vortex separator which squeezes the air to the centre and then to the top of the tank. SCAVENGE PRESSURE OIL PUMP ASSEMBLY MCD MASTER MCD MCD OIL COOLER OIL TANK Scavenge Oil passes through Air/Oil Separator

18 Oil Systems Oil System with Air Sealing SCAVENGE PRESSURE OIL PUMP ASSEMBLY MCD MASTER MCD MCD OIL COOLER OIL TANK Scavenge Oil passes through Air/Oil Separator Gearbox Drive Clean(?) Air Overboard The air in the tank passes to a Centrifugal Breather, with a vent line from each bearing chamber. Driven by the engine gearbox, the air is throws out and the oil returned to the tank. Centrifugal Breather

19 Oil Systems Oil System with Air Sealing SCAVENGE PRESSURE OIL PUMP ASSEMBLY MCD MASTER MCD MCD OIL COOLER OIL TANK Scavenge Oil passes through Air/Oil Separator Gearbox Drive Clean(?) Air Overboard Centrifugal Breather Centrifugal Breathers are never 100% effective, and oil loss can be visible as a blue-ish smoke. Too much smoke shows over filling of oil or other problems like bearing chamber seal failure.

20 Check of Understanding What type of oil system do modern jet engines have? Dry Sump Scavenger System Sealed Sump Redirecting System Sealed Sump Centrifugal System Dry Sump Recirculating System

21 What is fitted into a scavenge system to check if bearings are disintegrating? Magnetic Chip Detectors Magnetised Coil Detectors Magnetic Coil detectors Magnetised Chip Detectors Check of Understanding

22 In the bearing oil supply, the oil is delivered under pressure to a jet. Once the oil has passed through the jet, which of the following applies? Its pressure remains the same Its pressure becomes the same as the bearing chamber pressure Its pressure becomes more than the bearing chamber pressure Its pressure becomes less than the bearing chamber pressure Check of Understanding

23 In the bearing oil supply, why do the bearing chambers need to be sealed? To withstand outside air pressure To prevent the loss of oil To maintain oil temperature To maintain the oil pressure Check of Understanding

24 In the bearing system, air sealing vents are added, contact seals cannot be applied because.... The bearings would be inoperative if contact seals were used The oil and air pressure is too high The oil and air temperatures are too high The bearings are situated between rotating and static parts of the engine Check of Understanding

25 If blue-ish smoke is exiting an engine, which of the following could apply? Bearing particles in the system Damage to the centrifugal breather Bearing chamber seal failure Too little oil in the system Check of Understanding

26 JET PROPULSION End of Presentation


Download ppt "JET PROPULSION Part 5 Jet Engine Operation Oil Systems."

Similar presentations


Ads by Google