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

B.1 Experiment Operation Conditions for Droplet Array Combustion
not be controlled precisely enough to follow a perfect free-fall trajectory. Thus,
buoyant motion and other accelerative disturbances are usually not entirely
suppressed. On the other hand, sophisticated drop tower facilities can provide
a microgravity level of 1×10 −4 to 1×10 −6 g 0 for 2 to 10 s of experiment time
[66, 235].
Hence, the engineering module (EM) of the experimental unit was used in
parabolic flight for initial tests in the microgravity environment. For this purpose,
a parabolic flight campaign (PFC) was conducted with Diamond Air Service
(DAS) in Nagoya, Japan, in October 2007. The campaign consisted of two
flight days with ten parabolas each. The main novelty was the integration of
the EGS system into the former DCU (see Figs. 3.2 and 3.9). In order to ensure
relevance and comparability, the total amount of fuel and the overall length of
the droplet array were kept constant to the final sounding rocket setup. The
results of the PFC were satisfying in qualitative and quantitative terms. All
control systems were operable, and the measurement units produced useful
results and could be adjusted regarding range and resolution [294].
The drop tower campaign was conducted at the facility of ZARM (Zentrum für
angewandte Raumfahrttechnologie und Mikrogravitation) in Bremen, Germany,
in July 2008. It comprised 30 drops nominally. The EM was used again,
and the campaign itself was termed “TEXNOX”, which is derived from TEXUS
and NO x . Here, the precursor experiments included preheating of the combustion
chamber in the range of 300 to 500 K and droplet arrays consisting of
9 to 17 droplets (cf. Tab. B.1). Microgravity time was 4.74 s. Apart from generating
a basis of scientific results, all operational parameters and procedures
were reevaluated and recommendations given for the subsequent sounding
rocket campaign [294].
PHOENIX Experiment on TEXUS-46
Sounding rocket flights provide a microgravity time of 200 to 900 s at a typical
microgravity level of 1×10 −4 g 0 [66, 235]. Main advantage is the extended microgravity
time in the range of several minutes combined with a very good microgravity
quality. On the downside of the sounding rocket environment are
limited remote access by telecommand, severe restrictions in weight, dimensions
and power consumption, long preparation and qualification phases,
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