How does it keep from flowing into the turbine itself?
Lubricant is fed to the bearings. What's the problem?
The bearings are located outside the casing on either end of the shaft. There is an oil pump that circulates oil through the bearing. A seal on the shaft keeps the oil from flowing into the turbine casing.
Oil lubrication is done by dry sump - Dry sump for jet engines (separate oil tank) - Typical oil tank capacity of a JT9D engine is 25 liters - On jet engines - oil is prayed on main bearings then scavenged back to the oil tank - Oil in jet engines is cooled by a fuel heat exchanger (radiator) - Jet engines only use synthetic type oils - such as Mobil II or Esso/Exxon 2380 - Note to Piero - As you know, main bearings leak oil when engine failed and is windmilling - In case of absence of bleed air pressure -.
The bearings actually have air seals! Labyrinth seals with air, to prevent cooling and lubricating oil from entering the airflow. If a piece of carbon or foreign matter enters the seal, it often causes oil consumption. Most engines use fuel to oil cooling.
There are many requirements for turbine engine lubricating oils. Due to the absence of reciprocating motion and the presence of ball and roller bearings (antifriction bearings), the turbine engine uses a less viscous lubricant. Also, with high-speed antifriction bearings, the formation of carbons or varnishes must be held to a minimum. For this reason synthetic oil is used in turbine engines. Both wet- and dry-sump lubrication systems are used in gas turbine engines. Wet-sump engines store the lubricating oil in the engine proper, while dry-sump engines utilize an external tank mounted on the engine or somewhere in the aircraft structure near the engine, similar to reciprocating piston engines mentioned earlier. Turbine engine’s oil systems can also be classified as a pressure relief system that maintains a somewhat constant pressure: the full flow type of system, in which the pressure varies with engine speed, and the total loss system, used in engines that are for short duration operation (target drones, missiles, etc.). The most widely used system is the pressure relief system with the full flow used mostly on large fan type engines. One of the main functions of the oil system in turbine engines is cooling the bearings by carrying the heat away from the bearing by circulating oil around the bearing.
