What does the term "bleed air" refer to in turbine engines?

The term "bleed air" in turbine engines specifically refers to compressed air that is extracted from the engine, typically from the compressor section, for various auxiliary purposes. This extracted air can be utilized for a number of functions, including cabin pressurization, engine starting, and de-icing systems. The ability to use this high-temperature and high-pressure compressed air enhances the overall efficiency of the engine and contributes to various essential aircraft systems.

For instance, bleed air is often directed to the turbine engine's accessories, such as pneumatic systems that power air conditioning and environmental control systems within the aircraft. Additionally, it plays a critical role in starting the engine, helping to initiate combustion in the engine's combustion chamber.

Understanding bleed air is crucial for comprehending how turbine engines not only function but also support various systems within an aircraft, highlighting its importance in overall aircraft operation and efficiency.