Future Trends in Commercial Aviation Engines’ Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 124

Fig. 14 EINO x versus 1000/T f of Comb 7 (from Mongia 2010a ) compared with the TFE731-2
data from Diehl and Biaglow ( 1974 ); the latter is identi ed as the first generation modern
propulsion engine and the former as N generation.

T f is the adiabatic stoichiometric flame

temperature computed from reported P 3 and T 3 data

stoichiometric flame temperature), it is premature to recommend this approach for

all rich-dome engines to calculate the mission NO x emission. The similarity of these
two engines

fl

NO x versus stoichiometric curves and those in Fig. 13 discussed
earlier forces one to wonder how much rich-dome NO x reduction we can claim, and
therefore providing motivation for alternative design approaches.
Recalling from Fig. 13 , the takeoff NO x emissions of the set of several low rich-
dome combustors are represented well by a simple empirical correlation of their
takeoff pressure ratio. However, when the LTONO x data of these engines expressed in
terms of the average LTO NO x , the correlation quality deteriorates signi

'

cantly,

F 0 hi

namely DP 7319PR 0 : 9483

2

fit of these engines is
sought in terms of the characteristic LTO NO x (Fig. 15 ), the resulting expression is
worst off, namely DP

RD L ¼

1 : w = R ¼ 0 : 8459. When data

F 0 hi

6692PR 0 : 8552

2

RD L ¼

2 : w = R ¼ 0 : 6593 :

ning
RD-L, namely when it does not include the Trent1000 average LTO NO x . This is
obvious by looking at Fig. 15 which shows characteristic LTO NO x versus takeoff

However the quality of the empirical fit improves considerably by rede

Fig. 15 Characteristic LTO
NO x of the lowest NO x rich-
dome large engines as de ned
in Fig. 13