64.12 Turbine Engine Turbine Section

64.12.2 State the purpose and operation of the turbine section.

The turbine section of a gas turbine engine extracts energy from the hot, high-pressure gases leaving the combustion chamber and converts it into mechanical energy.

The turbine section is made up of one or more turbine stages. Each stage normally consists of:

• a row of stationary nozzle guide vanes; and

• a row of rotating turbine blades.

The nozzle guide vanes:

• direct the hot gases onto the turbine blades at the correct angle; and

• accelerate the gas flow before it reaches the turbine rotor.

The turbine blades:

• extract energy from the gas flow;

• convert this energy into rotational motion; and

• drive the turbine shaft.

The turbine shaft may be used to drive:

• the compressor;

• the engine accessory gearbox; and

• in a turboshaft engine, the power turbine and rotor system.

Because the turbine operates in extremely high temperatures, turbine components may be protected by:

• cooling air taken from the compressor;

• heat-resistant materials; and

• protective coatings.

The turbine section therefore converts the energy in the hot combustion gases into useful mechanical power.

64.12.4 Describe the function of the following turbine assembly components: