Environmental Engineering Reference
In-Depth Information
Fig. 13 Self-illuminated images showing oscillations of a n-decane droplet
ame (D
o
= 5.1mm) as it
radiatively extinguishes (Liu et al.
2014a
). Time between images is 0.17 s. Flame peels away from the
droplet (the droplet is not visible in these
fl
fl
flame images) and then closes around the droplet as the
fl
flame is re-established. Specks in background are from video sensor imperfections. (Also see this
180952454/
). a Flame opens-up. b Flame closes-back
6 Combustion Properties of the Spherical Droplet Flame
Conguration
As remarked previously and depicted in Fig.
4
, the combustion properties for the
spherical droplet
flame diameter (D
f
), and the
soot shell diameter (D
s
). These dimensions are obtained by a frame-by-frame analysis
of the digital video record of the droplet burning history. Computer-based algorithms
have been developed for this purpose (Dembia et al.
2012
). The droplet diameter is
relatively easy to measure while the
fl
flame are the droplet diameter (D), the
fl
flame, and especially the soot shell diameter, can
be challenging and time-consuming to extract from images like those shown in
Fig.
11
because the
fl
flame and soot shell boundaries are not especially distinct. As
such, the effort to extract droplet dimensions can be quite arduous, especially if soot
obscures part of the droplet boundary which can create gaps in the measurements. The
following illustrates results of using combustion properties obtained from the
experimental designs of Figs.
5
and
6
to assess performance of surrogates.
To be effective, a surrogate should replicate the combustion properties of the real
fuel
fl
guration. Arguments have been previously
presented for the suitability of the spherical droplet
in a suitable combustion con
guration to serve that
purpose. Using the evolution of droplet diameter as a combustion property for the
spherical
fl
ame con
guration (Fig.
4
), Fig.
14
compares an 87 octane gasoline (no
ethanol) with toluene and mixtures of heptane and toluene. A binary mixture is the
fl
ame con
Search WWH ::
Custom Search