Airplane Engines - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 148

primary air
secondary air

twist rose
injection nozzle

film cooling

fuel ignition

vortex

combustion chamber housing
cooling air
flame pipe

1 2 3 4 5 6

1. diffusor channel between compressor and
combustion chamber
2. division of the air throughput into primary and
secondary air
3. mixing and gasification zone

4. combustion zone
5. thinning zone
6. smoothing of the flow in the combustion
chamber`s exhaust zone

Fig. 10.2 Main elements of a jet engine's combustion chamber

10.2 Fuel Consumption and Thrust

Development is moving toward higher bypass ratios, larger fan diameters, higher
masses, higher thrusts, and lower fuel consumption rates.
Currently, thrust and speed are presenting continuously increasing and SFC
decreasing tendencies in aviation (see Table 10.2 )[ 10 ].
The production costs of jet engines are increasing. The price range of modern
turbofan engines is from €10 to 30 million, i.e., from US $14.3 to 43.9 million.
Increasing the bypass and pressure ratio without increasing the fan diameter
means less core flow which increases the temperature at the turbine inlet [ 11 , 12 ].
The control of the combustion chamber needs additional micro sensors for burning
and exhaust gas products. Self-Diagnosis will become more important since
modern jet engines are constructed with higher loads and higher durability.

10.3 Construction of the Combustion Chamber

In the combustion chamber the burning process produces high pressures and high
temperatures according to the mixture conditions. Most combustion chambers
operate with an air surplus in the burner can [ 13 ]. The mixture in the combustion