MODELING AND VISUALIZATION OF COMBUSTION
USING FLUID SIMULATOR AND PARTICLE SYSTEMS
Marek GAYER, Doctoral Degree Programme (3)
Dept. of Computer Science and Engineering, FEL
Czech Technical University in Prague
E-mail: xgayer@fel.cvut.cz
Supervised by: Prof. Pavel Slavík
ABSTRACT
Nowadays, modeling and visualization of various physical and nature phenomena using
fluid simulators and solvers based on the Navier-Stokes equations has major theoretical and
practical importance in simulation and especially computer graphics field.
We have developed fast and simple fluid simulator for real-time simulation and
visualization of combustion processes in pulverized coal boilers used in power engineering.
We have extended the general concept of fluid simulator with our real-time virtual particle
system engine for both simulation and visualization of combustion processes. We use the
industry standard OpenGL platform for reliable and fast visualization. Our results are suitable
for both the education and preview design of power-plants boilers.
1 INTRODUCTION
Nowadays, simulation and visualization of various physical and nature phenomena
using fluid simulators and solvers based on the Navier-Stokes equations has major theoretical
and practical importance in simulation and especially computer graphics field. These
simulators and solvers are widely used for various research projects and practical applications
such as animations of liquids and water [1], fire, gas and smoke, and many others. Some of
them are used for special effects such as melting and animations in movies.
We have developed fast and simple fluid simulator for real-time simulation and
visualization of combustion processes in pulverized coal boilers used in power engineering.
We have extended the general concept of fluid simulator with our real-time particle system
engine for both simulation and visualization of combustion processes.
2 FLUID SIMULATOR FOR COMBUSTION SIMULATION
Our fluid simulator is on the top level consists only of application of the two physics
laws – Newton’s Second Law and The Continuity Equation [2]. The heat and temperature
changes generated during the combustion processes are computed using a simplified
combustion and heat transfer engine. The fluid simulator also allows distribution of the heat
by the moving air mass inside simulated area (e.g. boiler interior).
The simulated area is divided to 2D structured grid cells. In each step we calculate the
new characteristics (e.g. velocities, masses) for all grid cells. All calculations are reduced on
nearest neighbors of the calculated cells, see Figure 1. We periodically repeat these
computations in each time step of the simulation. We use the fluid simulator results as Flow
Array, which determines the movement of coal particles inside the simulated area.
T = 303K (above ignition)
O
2
concentration = 60%
Coal particle
Partially burned particle
Coal particle transformed to
burned gas particle
C
C
C
C
B
Fig. 1:
Left: Division of the boiler area to 2D grid cells. The cell values in the next time
step are computed from nearest neighbors only. Right: Interaction of coal particles with
air contained in grid cells
3 COAL PARTICLE SYSTEM
We use a coal particle system, enabling easy and fast computation of the combustion
processes. In our system, the particle system allows us both the computation and visualization
of coal mass elements in the boiler. The particles displayed and calculated do not correspond
to the real coal particles in the boiler. Instead, they represent corresponding mass of coal in
the cell under investigation. The quality and speed of both simulation and visualization can be
altered by increasing or decreasing the amount of particles.
Instead of simulation of these processes using classical complex differential equations
approach, we use a simple, statistical view of the combustion process [3]. The combustion
and heat transfers and fluxes are being computed separately for single grid cells (containing
air mass), and corresponding particles inside them, see Figure 1.
4 VISUALIZATION OF THE RESULTS
Our system uses the industry standard OpenGL platform for reliable and fast
visualization. This means that our system could be used on a standard low-cost graphics
accelerator. We use OpenGL linear interpolated quads with the support of the graphics
hardware acceleration for visualization of the cell characteristics, see Figure 2.
There is no lack of speed in particle visualization even when using coal particle streams
consisting of ten-thousands of particles, see Figure 3. The selected local characteristics in the
voxel, such as the total temperature, mass storage, the wattage, and heat flux state and/or
changes can be visualized in real-time. Utilizing the advantage of the particle system concept,
we can easily construct the particle traces. We produce this effect by saving the previous
particle positions and characteristics. After that we can draw the particles in current time step
together with the kept ones. The particle traces can clearly indicate the velocities and direction
of move of coal particles, which are visible even on the static state picture, see Figure 4.
Fig. 2:
Visualization of the combustion temperatures of the power-plant boiler. The
greatest temperatures are in the core of the flame tube
Fig. 3:
Visualization of particles using full hardware accelerated, combined smoothing
and blending of drawn pixels gives acceptable visual quality even with a high zoom level.
Fig. 4:
Real-time visualization of partial particle traces helps in determining particle
speed, direction and dynamics even in static images.
5 CONCLUSION
Our real-time pulverized coal combustion simulation and visualization system is based
on the fast fluid simulator and particle system. The high speed of the fluid simulator and
combustion powered by particle system and simplified combustion engine allows real-time
visualization of the results (using OpenGL graphics interface).
This results in the possibility to get an interactive preview of the dynamics of
combustion processes in a boiler. The students and developers of the combustion boilers
could now test many configurations and modifications of pulverized coal boilers interactively
with an immediate response.
ACKNOWLEDGEMENTS
This project has been partially supported by the Ministry of Education, Youth and
Sports of the Czech Republic under research program No. Y04/98: 212300014 (Research in
the area of information technologies and communications).
REFERENCES
[1] Stam, J.: Stable Fluids. In: Proceedings of SIGGRAPH '99, ACM Press/Addison-Wesley
Publishing, 1999, 121-125
[2] Gayer, M., Slavík P., Hrdlička F.: Interactive System for Pulverized Coal Combustion
Visualization with Fluid Simulator. In: Proceedings of 2nd IASTED International
Conference: Visualization, Imaging, and Image Processing, Acta Press, 2002, 288-293
[3] Gayer, M., Hrdlička, F., Slavík P.: Dynamic Visualisation of the Combustion Processes in
Boilers, Journal of WSCG 10(3), 2002, 25-32.
