Machines/5 min exploration

A jet engine's energy relay

Why does a jet engine need both a turbine and a nozzle?

A turbojet keeps an energy relay running. The compressor raises the pressure of incoming air. Fuel burning in the combustor adds energy to that compressed flow. The turbine takes enough energy from the hot gas to keep the compressor turning through the central shaft; the nozzle then accelerates the remaining exhaust.

3D model

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The turbine keeps the compressor running. The nozzle turns remaining exhaust energy into a faster jet.

What is the turbine's essential job in this simplified engine?

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How the parts work together

  1. 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.

  2. 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.

  3. 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.

  4. 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.

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