The Gas Turbine Process

Gas turbine engines are, theoretically, extremely simple. They have three parts:

  • Compressor - Compresses the incoming air to high pressure
  • Combustion area - Burns the fuel and produces high-pressure, high-velocity gas
  • Turbine - Extracts the energy from the high-pressure, high-velocity gas flowing from the combustion chamber

The following figure shows the general layout of an axial-flow gas turbine -- the sort of engine you would find driving the rotor of a helicopter, for example:

In this engine, air is sucked in from the right by the compressor. The compressor is basically a cone-shaped cylinder with small fan blades attached in rows (eight rows of blades are represented here). Assuming the light blue represents air at normal air pressure, then as the air is forced through the compression stage its pressure rises significantly. In some engines, the pressure of the air can rise by a factor of 30. The high-pressure air produced by the compressor is shown in dark blue.