Future Trends in Commercial Aviation Engines’ Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 115

Table 1 Engine level requirements from combustion system
1 Minimize mission fuel consumption

2 Meet ICAO and customer emissions requirements with margin to allow for future engine

growth

3 Operate over wide range of thrust, rapid, acceleration/deceleration, steady operation in

extreme rain and hail

4 Ground start, altitude relight

5 Hot-section (turbine) durability requirement

6 Combustor durability

7 Low weight and cost

Table 2 Combustion system level requirements
1 High combustion efficiency (>99.9 %) and low-pressure loss
2 Minimize emissions and smoke consistent with other requirements with attendant complex
tradeoff process
3 Wide stability/operability limits. Sustain fl flame during water and hail ingestion

4 Reliable and smooth ignition; fl flame propagation; steady-state combustion with high

combustion efficiency

5 Minimize combustor exit temperature nonuniformity consistent with speci ed radial

temperature distribution, core as well as near-wall regions

6 Low structure temperature levels and gradients. Coke-free fuel insertion system

7 Affordable cost material/mechanical/manufacturing design and material along with low

hot-streaks, reduced length and diameter

control your ATM machine otherwise you will run out of time and money in
producing a new combustion system requested by the project. We will discuss some
of these requirements in the following subsections relevant to this article.

2.3 Combustion Ef ciency

The need for high combustion ef ciency is quite obvious along the engine operating

lines from sea-level to cruise-altitude operation as it directly affects the mission fuel
burn. As shown in Figs. 8 , 9 and 10 , well-designed combustion systems have been
giving very good combustion ef

ciency since the early 1970s. The data shown in

these first engine for the author to learn from about

the art of combustion design and technology development when he started with
AiResearch Manufacturing Company, Phoenix in 1972. This dataset reported by
Diehl and Biaglow ( 1974 ) was from an altitude tank that simulated engine operating
conditions from minimum to maximum thrust at four different altitudes, namely
640, 4,570, 9,140, and 13,200 m. The data at 640 m included static (zero Mach
fl

figures are for TFE731-2, the

flight number M) engine operation simulating idle, 30 % and maximum takeoff