Environmental Engineering Reference
In-Depth Information
the
fl
flight envelope. Also shown in the
figure is the minimum margin on fuel air
ratio, identi
FAR which is known popularly as a pinch point.
Finally, engine must start reliably at ground on the all-time record coldest day at
the airports of interest; viz.
ed as
ʴ
C, respectively, in Moscow,
Anchorage, and Montreal. The numerical values of the dome design pressure drop
(
−
42,
−
39 and
−
34
°
Δ
P
design
) and the minimum and maximum fuel air ratios (FAR
min
and FAR
max
)
depend upon the combustion system design and its potential applications. We will
assume typical values of these variables, respectively, 3
-
5 %, 0.005
-
0.008, and
0.025
0.040 for the aviation engines.
In summary, combustor must meet its design requirements for the inlet pressures
and temperature ranges listed for the N + 2 generation engines operating at takeoff
60 OPR; T
3
: 216.67
-
-
1084 K; P
3
: 0.33
-
60 atm;
Δ
P:
(0.1
-
1.2)
Δ
P
design;
and FAR:
*
FAR
min
−
first generation small
and large engines presented previously in Table
4
. The ratio of the operating
pressures will go up from 41 to 180 and that of T
3
from 3.1 to 5.0. The operability
challenge for the lean domes is obviously more than that of the rich dome.
FAR
max
. These ranges can be compared with the
3 First Alternative to Rich Domes
3.1 First Generation LDI in Product
Bahr and Gleason (
1973
) conceived and started the technology development effort
on a dual-annular combustor DAC (Fig.
22
) which may be compared with the rich-
dome single annular combustor (SAC) presented earlier in Fig.
2
. Its outer annulus
(Pilot) is similar to SAC in operation from engine start to some intermediate power
setting, generally approach, beyond which the inner annulus (Main) combustor gets
fueled followed immediately by ignition and
fl
flame propagation with the hot
Fig. 22 A typical dual-
annular combustor (DAC)
cross-section; from Mongia
(
2003
)
Search WWH ::
Custom Search