Environmental Engineering Reference
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t = 0.03s
t = 0.07s
t = 0.10s
t = 0.13s
t = 0.17
t = 0.20s
t = 0.23s
t = 0.27s
t = 0.30s
t = 0.33s
t = 0.37s
t = 0.40s
t = 0.43s
t = 0.47s
t = 0.50s
t = 0.53s
Fig. 6 Still images of the
fl
flame at 80 lpm with
Δ
t = 33-ms intervals observed near LBO, i.e.,
Φ
/
Φ
LBO
= 1.0, L
fuel
= 15 cm (port 5) (Chaudhari et al.
2013
)
observed the same extinction and reignition events (precursor to blowout) on the
swirl-stabilized dump combustor, which matches with the basic design of the present
experimental setup, with lean premixed methane
air
fl
ame.
-
Φ
LBO
= 1 for port 5 case, where the
premixing length is minimum (L
fuel
= 15 cm). The low premixing length for fuel
Figure
6
shows the images of the
fl
ame at
Φ
/
-
air mixing ensured that the
fl
flame obtained in the combustor is with lower degree of
fuel
air premixing or mostly partially premixed condition. From Fig.
6
,itis
revealed that all the time the
-
fl
flame is attached to the dump plane and not shows any
liftoff pattern. Though the
fl
ame shows some
fl
flame loss events where the
fl
ame
intensity is signi
ame does not
oscillate in the combustor, and the precursor events are not so intense. The
cantly reduced and later reignition of
fl
ame, the
fl
ame
base is attached to the dump plane all the time, which is in contrast to the obser-
vation of port 1
fl
low rates exhibits more
cycles of oscillation in near LBO regime, whereas in higher
fl
flame characteristics. The
fl
flame in low
fl
fl
flow rates, a less
number of oscillation cycles were observed.
For sensing techniques, the quanti
flame characteristics prior to blowout
have been explored to obtain LBO metric and use for detecting the LBO. The
sensing methodology presented in the current study is based on optical emission,
i.e., chemiluminescence and
able
fl
flame color variation analysis from combustor. The
present study used chemiluminescence from CH radicals (emitted at 432 nm.) for
detecting the lean blowout. The choice of optical sensing allows the optical sensor
to be located outside the harsh environment of combustor so that the requirements
of non-intrusive sensing can be ful
fl
lled. Further,
inherent fast
time response
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