Page 45 - The Jet Engine

4: Combustion chambers

Contents Page

Introduction 35
Combustion process 36

Fuel supply 38

Types of combustion chamber 38
Multiple combustion chamber
Tubo-annular combustion chamber
Annular combustion chamber
Combustion chamber

performance 41

Combustion intensity
Combustion efficiency
Combustion stability Emissions
Materials 43

INTRODUCTION the turbine blades and nozzles are made. The air has
already been heated to between 200 and 550 deg. C.
1. The combustion chamber (fig. 4-1) has the by the work done during compression, giving a
difficult task of burning large quantities of fuel, temperature rise requirement of 650 to 1150 deg. C.
supplied through the fuel spray nozzles (Part 10), from the combustion process. Since the gas
with extensive volumes of air, supplied by the
compressor (Part 3), and releasing the heat in such temperature required at the turbine varies with
a manner that the air is expanded and accelerated to engine thrust, and in the case of the turbo-propeller
give a smooth stream of uniformly heated gas at all engine upon the power required, the combustion
conditions required by the turbine (Part 5). This task chamber must also be capable of maintaining stable
must be accomplished with the minimum loss in and efficient combustion over a wide range of engine
pressure and with the maximum heat release for the operating conditions.
limited space available.
3. Efficient combustion has become increasingly
2. The amount of fuel added to the air will depend important because of the rapid rise in commercial
upon the temperature rise required. However, the aircraft traffic and the consequent increase in
maximum temperature is limited to within the range atmospheric pollution, which is seen by the general
of 850 to 1700 deg. C. by the materials from which public as exhaust smoke.

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