Environmental Engineering Reference
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Fig. 48 Comparison between EIHC correlations versus data from idle to maximum takeoff thrust
for the modern rich-domes, namely Comb 1, Comb 2, Comb 5, Comb 6, and Comb 7. The range of
the root-mean-square errors is 0.07
-
0.74 EI; Source Mongia (
2010a
,
b
)
Table 7 Range of P
3
, T
3
,NO
x
, CO, HC and T
Tstoich
for applicable correlations of Figs.
46
,
47
and
48
0
R
0
R
T
3
,
P
3
, psi
HCEI
COEI
NO
x
El
Tstoich,
Max
1,662
650
43
100
63
4,806
Min
733
36
0
0
3
4,234
*
430
a
*
1,000
a
Max/Min
2.3
17.9
22.3
1.135
a
Arbitrary, minimum value assumed 0.1 El
minimum, and the ratio max/min in Table
7
. In order to avoid diving by the zero
values of minimum HC and CO to calculate the max/min ratio, we assumed an
arbitrary minimum value of 0.1 EI for HC and CO. It is interesting to note that with
the max/min ratios of 2.3 and 17.9 for T
3
and P
3
, we get the corresponding ratios of
1.135, 22.3, 430, and 1,000 for T
Tstoich,
,NO
x
, HC, and CO, respectively. This clearly
illustrates the complexity of achieving reliable engineering correlations. Never-
theless, it is very interesting and encouraging to see the level of agreement for all
the three species (NO
x
, CO and HC) in terms of the root-mean-square and maxi-
mum errors for EI and %EI as summarized in Table
8
. We feel that eventually CFD
Table 8 Root-mean-square (RMSE) and maximum errors for correlating sea-level NO
x
, CO, and
HC along engine operating lines of the selected five combustors
Combustor
1
2
5
6
7
El
%
El
%
El
%
El
%
El
%
No
X
RMSE
0.23
1.21
0.444
3.11
0.34
1.63
0.32
1.47
0.47
1.86
Max
1.129
3.85
1.404
8.5
1.069
5.5
0.972
3.1
1.726
7.57
a
a
a
a
CO
RMSE
0.738
3.25
2.474
0.864
0.327
0.488
a
a
a
a
Max
3.063
12.48
13.098
3.153
1.4
1.363
a
a
a
a
HC
RMSE
0.188
12.9
0.741
0.164
0.068
0.122
a
a
a
a
a
Max
0.868
4.36
0.621
0.383
0.453
a
Values too close to zero
'
s making ratios in terms of % not relevant
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