On the Formation of Nitrogen Oxides During the Combustion of ...

5.5 Final Evaluation of Results
0.40
g kg −1 Initial temperature T g,0
Emission index of NOx EINOx
0.30
0.20
0.10
0.00
D 0 = 0.900 − 0.030 mm
D 0 = 1.000 ± 0.030 mm
300 400 500 K
Figure 5.23: Impact of Initial Droplet Diameter and Preheating Temperature on NO x Emissions
for Droplet Arrays. All data displayed is obtained from droplet arrays with
an inter-droplet distance of S=4.5mm and a number of N = 17 droplets [294].
5.5 Final Evaluation of Results
In particular, the extended microgravity duration of sounding rocket flight allowed
for investigation of the pre-vaporization rate Ψ. The scientific quality
of the results is very good and shows a high consistency with the precursor
experiments from parabolic flight and drop tower, which were a substantial
part of the present study. All these physical experiments comprise a temperature
range of 300 to 500 K, initial droplet diameters in the range of 0.819 to
1.608 mm, droplet numbers from 5 to 17, and pre-vaporization time in the
range of 0 to 18s, resulting in pre-vaporization rates from 0.00 to 53.78 %. The
experiment procedures, including those of exhaust gas sampling and analysis,
were verified additionally by the values measured for CO 2 , CO, and H 2 O.
These are in line with combustion theory. Particular combustion phenomena
observed were predicted beforehand. These include the formation of a triple
flame with an increase in pre-vaporization rate Ψ. All exhaust gas concentrations
were corrected for secondary effects, such as fresh air entrainment into
the combustion chamber and heat loss of the combustion chamber.
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