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