Developing Surrogates for Liquid Transportation Fuels: The Role of Spherically Symmetric Droplet Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 376

Fig. 3 Context of the spherically symmetric droplet burning configuration to the stochastic
environment of an engine

A hierarchy for combustion of a liquid fuel is envisioned as depicted in Fig. 3
that includes a full spray, 3-D multi-droplet cloud, and 2-D array with inter-droplet
spacing

gurations is yet amenable to ab initio
modeling that includes simultaneously the effects of time-dependent gas and liquid
transport, moving boundary of the liquid/gas interface as evaporation occurs, var-
iable properties, detailed combustion chemistry, and radiation. Even if L is arbi-
trarily

“ L ” . For finite L, none of these con

such that a single isolated drop is realized but convective effects are
still present, detailed numerical simulation has not yet been accomplished, though
approaches have included some (but not all) of these elements (Sirignano 1999 ).
Currently, it appears that only for the single stationary isolated droplet (L

“ large ”

→ ∞
in Fig. 3 ), burning in a quiescent ambience with no convective effects (forced or
buoyancy-induced) can detail numerical simulation based on a

first-principles
solution be carried out that incorporates all the physical processes mentioned above,
except for soot formation (Farouk et al. 2013 , Liu et al. 2013a ; Cuoci et al. 2005 ).
Figure 4 a is a schematic of this con guration.

The gas fl flow will be one-dimensional and only in the radial direction, and the

fl flow is created entirely by the evaporation process. If soot forms [Fig. 4 b, c (Liu

et al. 2014a )], the soot aggregates will be trapped between the droplet and fl ame by

the forces acting on the particles (Avedisian 1997 ). The con guration of

“ ”

Fig. 4 represents the base case of liquid fuel combustion as a building block for

complex droplet con gurations that lead to spray dynamics.