Environmental Engineering Reference
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X
2
+
(1, 0) transition
Q
1
(10) rotational line
A
2
ʣ
II
5cm
(
= 284.413 nm, 289.016
nm)
z
H
2
-Air
diffusion flame
Burner
(i.d.: 5 mm, o.d.: 15 mm)
r
Water Aerosol
Nebulizer
Cylindrical
lens
H
2
Air
Electrical heating
Deuterium oxide
(D
2
O)
Flow rate (H
2
: Air): 0.84 : 2.0
[l/min]
Steam flow rate of D
2
O: 46.1
[mg/min]
Fig. 8 The schematic diagram of the PLIF system utilizing isotope effect
Figure
9
shows the isotope effect for the rotational lines Q
1
(10) of OH and OD
caused by the difference in atomic mass between H and D. When the dye laser is
tuned in either excitation line, the PLIF detector can selectively measure OH or OD
fl
fluorescence followed by reconstruction of either image in the
ame.
Figure
10
demonstrates the OH and OD LIF images. The sectional pro
fl
le along
with the combustion axis clearly visualized for OH and OD radicals in the
fl
ame.
This images are proportional to their concentrations.
Figure
11
shows the
les reconstructed by thermocouple
measurements. The PLIF signal is almost independent on this
fl
ame temperature pro
ame temperature.
However, the dissociations of H
2
OorD
2
O molecules are dependent on the
temperature. Therefore, the PLIF images do not directly re
fl
ect the mixing condi-
tions. We, therefore, estimated a ratio of D
2
OtoH
2
O concentrations on the basis of
the chemical equilibrium equation as a function of the OH and OD concentration
(Fig.
10
) and the temperature (Fig.
11
), followed by its image reconstruction
(Fig.
12
).
fl
½
D
2
O]/[H
2
O]
max
½
½
½
D
2
O]/[H
2
O]
It is clearly indicated that the ratio is higher in the peripheral zones. This sug-
gests that the mixing is inadequate even in the hydrogen
fl
flame where the mutual
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