1 · Fan
The large first stage. Most of the air it moves goes around the core through the bypass duct, and in a high-bypass engine that bypass air makes most of the thrust.
Products example
Read-only showcaseA turbofan engine, stage by stage
An engineering cutaway where a part seen above and below the shaft is one region.
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Everything on this diagram
The same content as the picture, as text: every part and what it says when you open it.
Bypass duct
Carries the air that goes around the core. It leaves the engine cooler and slower than the core exhaust, which is why high-bypass engines are quieter and more efficient at airliner speeds.
2 · Low-pressure compressor
The first stages of compression inside the core, turned by the same shaft as the fan.
3 · High-pressure compressor
Squeezes the core air much further in many short stages. The passages narrow as the air is compressed, which is what the tapering shape shows.
4 · Combustor
Fuel is sprayed into the compressed air and burned continuously. The temperature here is the highest anywhere in the engine.
5 · High-pressure turbine
The first turbine after the combustor. The hot gas turns it, and it drives the high-pressure compressor through the inner shaft.
6 · Low-pressure turbine
Several larger stages that take more energy from the gas to drive the fan and the low-pressure compressor.
7 · Core exhaust
The core gas leaves around the exhaust cone, adding its share of the thrust.
Exhaust cone
The tapering centre body at the back of the core. The core exhaust flows out around it.
Spinner
The nose cone on the fan's hub, shaped to lead air smoothly into the fan.
Nacelle
The outer casing. Its lip shapes the air entering the fan, and it forms the outside wall of the bypass duct.
Low-pressure shaft
The inner of the two shafts: it connects the low-pressure turbine to the fan and the low-pressure compressor.
High-pressure shaft
A hollow shaft around the low-pressure one, connecting the high-pressure turbine to the high-pressure compressor. Two shafts let each part spin at the speed that suits it.
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