Page 29 - The Jet Engine

3: Compressors

Contents Page

Introduction 19
The centrifugal flow

compressor 21

Principles of operation
Construction
Impellers
Diffusers
The axial flow compressor 22
Principles of operation
Construction
Rotors
Rotor blades
Stator vanes
Operating conditions 28

Airflow control 29

Materials 29
Balancing 33

accelerate the air and a diffuser to produce the
required pressure rise. The axial flow compressor
(fig. 3-7 and fig. 3-8) is a multi-stage unit employing
alternate .rows of rotating (rotor) blades and
stationary (stator) vanes, to accelerate and diffuse
INTRODUCTION the air until the required pressure rise is obtained. In
1. In the gas turbine engine, compression of the air some cases, particularly on small engines, an axial
before expansion through the turbine is effected by compressor is used to boost the inlet pressure to the
one of two basic types of compressor, one giving centrifugal.
centrifugal flow and the other axial flow. Both types
are driven by the engine turbine and are usually 3. With regard to the advantages and disadvan-
coupled direct to the turbine shaft. tages of the two types, the centrifugal compressor is
usually more robust than the axial compressor and is
2. The centrifugal flow compressor (fig. 3-1) is a also easier to develop and manufacture. The axial
single or two stage unit employing an impeller to compressor however consumes far more air than a

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