Encyclopaedia Index TITLE : Smoke production simulated by a 100-fluid model
BY : CHAM Development Team (DB Spalding)
DATE : 1997
PHOENICS Version: 3.1

DETAILS :

Two streams, A, of gaseous hydrocarbon, and B, of air, flow into a duct of uniform cross-section. The flow is turbulent
A 100-fluid model is used, with mass fraction of A as the population-distinguishing attribute.
The parabolic integration mode is adopted.
A kinetically-controlled soot-production reaction is postulated, with rate proportional to unburned-fuel content and rising steeply with temperature.

RESULTS :

It is shown that neglect of the incompleteness of the micro- mixing leads to predictions of soot-production rates which differ radically, magnitude and distribution, from those predicted by the multi-fluid model. Changing from 100 to 10 fluids has little effect.

REFERENCE:

PHOENICS Input Library, Case.....

Contours of fluid-average temperature A = fuel inlet ; B = air inlet Duct wall ///////////////////////////////////////////////////////////////////////

B --->>>

////

A --->>> - ----- - ----- - ----- - ----- - ----- - ----- - ----- - --- Symmetry axis

Fluid-mean temperature

The fluid-average mass-fraction of unburned fuel
The fluid-average mass fraction of soot, computed on the basis of single-fluid-model assumptions, ie presuming perfect micro-mixing
The fluid-average mass fraction of soot, computed on the basis of multi-fluid-model assumptions, ie calculating the micro-mixing. The values differ radically, in both magnitude and distribution, from ...
those based on single-fluid assumptions
The fluid-average mass fraction of soot, computed on the basis of multi-fluid-model assumptions, ie with only 10 fluids

The values differ little from those based on the 100-fluid assumption, but greatly from the single-fluid values.

A series of PDFs computed for locations along the axis, progressively farther from the fuel-gas entry
pdf1

pdf2

pdf3

pdf4

pdf5: Fluctuations are dying out

wbs