Follow the explanation
Back to the model ↑How the parts work together
Compress the incoming air
The blue rotor blades add energy to the air. Between them, silver stator rows stay attached to the casing and redirect the flow. Together the stages raise pressure. Scrub the shaft angle to distinguish moving and fixed rows.
Add energy in the combustor
Look into the ring-shaped chamber between compressor and turbine. The shaft passes through its centre, outside the burning passage. Fuel injectors feed the chamber; the orange shapes indicate heat addition, not calculated flames.
Close the energy loop
Isolate the rotor. The copper turbine wheels and blue compressor wheels share one shaft. Pause and scrub its angle: the two gold index blades turn through exactly the same angle. These painted markers help you follow the motion. Hot gas powers the turbine, and the shaft carries that power back to the compressor.
Accelerate the remaining exhaust
After the turbine, exhaust passes around the tail cone and through the converging outlet. The nozzle converts remaining gas energy into exhaust speed. Its shape is shown here; gas velocity and thrust are not calculated.
The main parts
- Inlet
- Guides outside air into the engine core. This cutaway starts its story at the inlet rather than modeling an aircraft intake.
- Compressor
- Rows of rotating and fixed blades raise the pressure of the air before it reaches the combustor.
- Combustor
- Fuel injectors feed an annular chamber: a ring around the central shaft, not a fire through it. Burning adds energy to the compressed air. Orange shapes are a heat cue, not simulated flames or temperature readings.
- Turbine
- Hot gas turns turbine blades. The turbine and compressor are linked by the same central shaft in this single-spool schematic.
- Central shaft
- Transfers mechanical power from the turbine back to the compressor. The model draws one shaft, not a multi-spool engine.
- Nozzle
- Shapes the exhaust passage. The nozzle accelerates the remaining hot exhaust; this lesson does not calculate thrust.
Questions worth exploring
Why does a jet engine need both a turbine and a nozzle?
They take different shares of the hot gas's energy. The turbine works like a windmill: it extracts energy from the flow and passes it back along the central shaft to turn the compressor. It leaves enough energy in the gas for the nozzle to speed it up, and because the exit speed is greater than the speed of the incoming air, the engine pushes forward. This model shows the energy relay but does not calculate thrust.
What happens inside the combustor?
Fuel is combined with high-pressure air from the compressor and burned. The chamber is an annulus, a ring around the central shaft, so the shaft passes through its middle without touching the flame. A perforated liner helps mix fuel and air. Older engines used separate cans, and some use a can-annular compromise. The orange shapes in the model are a heat cue, not simulated flames or temperatures.
NASA Glenn · Combustor and annular linerNASA Glenn · Turbojet engine
Why do modern jet engines use many compressor stages?
One axial stage raises the pressure by only about a factor of 1.2, but stages can be stacked, so eight give roughly 4.3. A single centrifugal stage reaches about 4, yet stacking them is hard because the flow must be ducted back to the axis each time, and the engine ends up wider. That is why large engines use rows of rotating and fixed blades, as in this cutaway. Blade counts and shapes here are illustrative.
How is a turbofan different from the turbojet shown here?
A turbofan wraps the core in a fan on a second shaft, so it has two spools. Part of the air passes through the fan and around the core, and the engine gets thrust from both the core and the fan. Because the core burns almost the same fuel, a turbofan produces more thrust per unit of fuel, which is why most airliners use one. This model has a single shaft and no fan.