Page 131 - The Jet Engine

11: Starting and ignition

Contents Page

Introduction 121
Methods of starting 122

Electric
Cartridge
Iso-propyl-nitrate
Air
Gas turbine
Hydraulic
Ignition 127

Relighting 131

2. The functioning of both systems is co-ordinated
during a starting cycle and their operation is auto-
matically controlled after the initiation of the cycle by
an electrical circuit. A typical sequence of events
during the start of a turbo-jet engine is shown in fig.
11-1.

INTRODUCTION
1. Two separate systems are required to ensure
that a gas turbine engine will start satisfactorily.
Firstly, provision must be made for the compressor
and turbine to be rotated up to a speed at which
adequate air passes into the combustion system to
mix with fuel from the fuel spray nozzles (Part 10).
Secondly, provision must be made for ignition of the
air/fuel mixture in the combustion system. During
engine starting the two systems must operate simul-
taneously, yet it must also be possible to motor the
engine over without ignition for maintenance checks
and to operate only the ignition system for relighting Fig. 11-1 A typical starting sequence of a
during flight (para. 28). turbo-jet engine.

121