TITLE : EXPLOSION IN AN OFFSHORE MODULE
BY : D J Freeman - CHAM UK
- A natural gas explosion in a full-scale offshore module
is simulated. The module has dimensions of 25m x 8m x 8m.
- The simulation is three-dimensional and the LVEL turbulence
model is used in conjunction with the Multi-Fluid Turbulent
Combustion model (see next page).
The Multi-Fluid Turbulent Combustion (MFTC) Model:
- The MFTC has been developed within CHAM to simulate the complex
combusting flows associated with explosions and flames more
- In this example the reacting mixture consists of four fragments,
of different (and fixed) composition and temperature (see next
page). Mixing of the hot and cold fragments creates the
intermediate fragments, with the hottest being hot enough to
react (i.e. burn) to form hot products.
- The rate of combustion is therefore controlled not only by the
rate of mixing (as in the Eddy-break-up model) but also by the
kinetic rate of reaction.
- The MFTC may be extended to any number of fluids, depending on
the requirements of the simulation.
The Multi-Fluid Turbulent Combustion Model (cont.)
- The four fluids used in this simulation were:
A, comprising of fully unburned fuel/air mixture,
B, a mixture of unburned gas and products at a temperature too
low for chemical combustion to proceed,
C, the same mixture but at a temperature at which the
chemical rate is significant, and
D, fully burned gas.
- A and D mix to form B and C, while A mixes with C and B with D
to form B and C respectively. C reacts to form D.
- The overall rate of combustion therefore depends on the mixing
rate and the rate of reaction.
The following pictures show the progression of the flame front
(coloured green!) with time. The ignition position is at the right
end of the module.
The images used in this example were produced using
TecPlot, which is available as an optional post-processor
TecPlot can be used to produce high-quality 3-dimensional
images showing geometry, vectors, Gouraud-shaded surfaces
The images have been reduced to 16 colours for use with
POLIS, which can reduce the quality of the viewed image.