Quantcast Section 10: Visible Emissions

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Section 10:
VISIBLE EMISSIONS
10.1
Studies on Minimizing Visible Emissions.  In 1980, the Navy
sponsored a program to study ways of minimizing visible emissions from test
cell and hush-house installations to meet a Ringelmann 1.0 (20 percent)
opacity criteria during all runups.  The study involved full-scale exhaust
plume observations [5] and model-scale tests using a smokey jet [12].  For the
full-scale observations and predictions, the opacity of the open air jet was
chosen as the reference value.  This opacity (defined in terms of Ringelmann
number) does not diminish due to typical jet mixing because, while the
particulate concentration decreases, the effective plume diameter increases.
The reference open air jet opacities of several engines are presented in Table
6:
Table 6
Open-Air Jet Opacities
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))),
*
*
POWER
JET
*  AIRCRAFT
RINGELEMANN NO.  *
ENGINE
SETTING
/)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))1
*
*
*
*
A-4
J-52 P408
Mil
0.75
*
*
A-6
J-52 P8
Mil
0.50
*
*
A-7
TF-30 P6
Mil
2.25
*
*
TF-41 A2
Mil
1.25
*
*
F-4
J-79 GE8, 10A
Mil
2.50
*
*
A/B
0.75
*
*
J-79 GE10B, C
Mil
0.50
*
*
A/B
0.50
*
*
F-8
J-57 P420
Mil
0.50
*
*
A/B
0.25
*
*
F-14A
TF-30 P412
Mil
0.50
*
*
A/B
0.50
.)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))-
10.2
Model-Scale Test Conclusions.  The following conclusions were
derived from the observations and model-scale tests:
a)  Maximum exhaust plume opacity typically occurs during engine
runup in maximum nonafterburning thrust.
b)  At maximum nonafterburning thrust, the open-air jet opacity of
most engine exhausts is below Ringelmann 1.0 (the important exceptions being
older J-79's and the TF-41).
c)  It does not appear practical to design an exhaust system that
exhibits a plume opacity less than that of an open-air jet.
d)  The jet mixing and deceleration process, typical of a low-loss,
straight-through augmenter plus ramp, yields an exhaust plume opacity only
slightly greater than that of an open-air jet.
e)  The limited dilution and subsequent deceleration typical of most
test cell exhaust systems, can result in an exhaust plume opacity many times
that of an open-air jet.
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