65.8 Turbine Engine Compressors

65.8.2 Describe the purpose of a compressor in a turbine engine. 

The compressor in a gas turbine engine serves to provide the precise amount of air needed for fuel combustion, delivering it at the correct pressure and velocity.

It transforms mechanical energy from the turbine into kinetic energy within the air.

This process accelerates the air, which then passes through a diffuser.

The diffuser slows the air, converting most of its kinetic energy (velocity) into potential energy (pressure) and some into heat.

65.8.4 Describe the basic principles of operation of centrifugal and axial flow compressors. 

Centrifugal-flow compressor

A centrifugal compressor increases the pressure of the incoming air by accelerating it outward from the centre of a rotating impeller.

The basic sequence is:

• Air enters axially through the eye of the impeller.
• The rotating impeller accelerates the air and throws it radially outward by centrifugal action.
• The air leaves the impeller at high velocity.
• It then passes through a diffuser, where the airflow is slowed and much of its velocity energy is converted into pressure energy.
• The compressed air is collected in a manifold or collector and directed towards the combustion section.