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Fig. 4 Images of syngas
(50 %H 2 /50 %CO)-air
partially premixed flames
established at ϕ =6(a) and
ϕ =16(b) in a counterflow
burner. Strain rate is 35 s 1
structure and extinction characteristics of PPFs in an opposed-jet burner. Figure 4
from this study depicts images of two such flames established at ϕ = 6 and 16. For
ϕ
= 6, which is just above the rich
fl
flammability limit of 50 %H 2 /50 %CO syngas-air
mixture, the
flame structure with a weak rich pre-
mixed reaction zone (RPZ) established close to the fuel nozzle and a non-premixed
reaction zone (NPZ) on the oxidizer side near the stagnation plane. As
fl
flame exhibits a typical double
fl
is
increased, the RPZ moves away from the fuel nozzle, and RPZ and NPZ are much
closer to each other. Som et al. also examined the effect of syngas composition and
partial premixing on NO emissions.
Ouimette and Seers ( 2009 ) reported an experimental investigation on syngas
partially premixed jet
ϕ
fl
flames. The effects of
,CO 2 dilution, and H 2 /CO ratio on the
ϕ
fl
ame structure and NO x were reported. Figure 5 from this study presents
fl
ame
images at different
. As expected, the
fl
flame length is strongly in
fl
uenced by the level
ϕ
of partial premixing. As
decreases from the non-premixed to premixed regime, the
ϕ
fl
flame length decreases monotonically. This has important consequences for the
emissions of NO x , greenhouse gases, and other pollutants, since the
fl
flame length
directly in
uences the reacting volume and residence time. In addition, images at 2.0
and 1.6 indicate the existence of two reaction zones, with the NPZ enveloping the
RZP. Regarding the NO x formation, results indicated that EINO x
fl
first increases as
ϕ
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