Future Trends in Commercial Aviation Engines’ Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 123

H 2 þ OH , H 2 O þ H ð 8 Þ

;

CO þ OH , CO 2 þ H ð 9 Þ

Leading to the following two expression for O:

½ ¼ K C 6 K C 8 H 2

½ ½ O 2

O ð 10 Þ

;

½ H 2 O

K C6 K C9 H 2 O ½ ½ CO ½ O 2

½ ¼ O ð 11 Þ

½ CO 2

or 4 ) through time-
temperature history leads to a simplistic model for NO emission provided it were a
one-dimensional

Integration of either of the NO rate expression (viz. 4 ′

fl flame problem. The product combustors exhibit highly complex

transient fl ow field characteristics which clearly cannot be duplicated by this simple

model.
An alternative approach comprised of empirical correlation along with air

ow
distribution was successfully used by Danis et al. ( 1996 ) to correlate NO x along the
engine sea-level operating points. But the air

fl

fl ow distribution information is gen-

erally not available publicly. Moreover, it varies signi cantly between engine

combustors. If one could use certi ed publicly available information on rated thrust,

fan bypass ratio, overall pressure ratio, and fuel

fl flow rate, in addition to LTO

emission data and fuel flow rates, one can formulate a simple approach for eval-

uating emission characteristics of all the rich-dome combustors. The feasibility of
this approach was demonstrated by Mongia 2010a for the sea-level operating lines
of the 7 rich domes out of the 12 rich-lean dome combustors discussed by Mongia
( 2008 ). In order to get information about P 3 and T 3 , one has to rely on the use of
performance model calibrated with the ICAO database (Kumar et al. 2012b ). The
feasibility of this approach was also demonstrated for altitude operation, viz. the
publicly available data of the TFE731-2. This methodology clearly shows that rich
dome

fl

sNO x emissions along the engine operating lines from sea-level to altitude
operation can be represented as a function of adiabatic stoichiometric

'

ame tem-
perature, and there is no need to use NO x severity parameter for correlating NO x
from different rich domes (Mongia 1997 ).
This approach led to very interesting results as shown in Fig. 14 which presents
EINO x of one of the N-generation rich-dome engine (viz. combustor 7) and the
TFE731-2. It should be pointed out that Combustor 7 data is for the sea-level
operation only whereas the TFE731-2 takeoff OPR is only 14. These two datasets
can be compared with Fig. 38 for the CFM56-2C, a 24 OPR engine. The TFE731-2
data presented in Fig. 14 encompasses NO x data from sea-level to 13,200 m altitude
operation with the corresponding pressure ratios ranging between 1.9 and 11.4.
Since only one engine

fl

sNO x data from sea-level to the altitude operation has been
used to show feasibility of the recommended approach (viz. EINO x as a function of

'