Bleed Air

Bleed air in gas turbine engines is compressed air taken from within the engine, after the compressor stage(s) and before the fuel is injected in the burners. While in theory bleed air could be drawn in any gas turbine engine, its usage is generally restricted to jet engines used in aircraft. This compressed air can be used within the aircraft in many different ways, from de-icing, to pressurizing the cabin, to pneumatic actuators. However, bleed air is quite hot and when being used in the cabin or other low temperature areas, it must be cooled or even refrigerated. Bleed air is valuable in an aircraft for two properties: Its high temperature and its high pressure.
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