Institute for Energy Process Engineering and Fuel Technology > Equipment > Computer lab for numerical flow simulation (computational fluid dynamics - (CFD))

Computer lab for numerical flow simulation (computational fluid dynamics - (CFD))

At the IEVB, a computer lab with a powerful server was built as the centerpiece of the system. In addition, there are also five workstations and a larger number of desktop PCs. The CFD-Fluent code is used as the basic software package. The code has been augmented by a series of application-specific subroutines, which were developed at the IEVB. Detailed calculations in regard to combustion chemistry are performed using the CHEMKIN program. The general method of mathematical modeling implemented at the IEVB involves using the advantages of each program, CHEMKIN and FLUENT, and combining the two to maximize efficiency. For example, computing stream and temperature fields with FLUENT gives us very good spatial resolution. Despite steady advances in computer technology, calculations such as these are still only possible on modern, high-performance computers using combustion models based on crude simplifications of the reaction mechanisms. The CHEMKIN approach follows a reverse philosophy: ovens are divided (using basic mechanics criteria) in distinct sections throughout the volume and displayed as reactor networks.

CFD software is basically a solver for Navier-Stokes equations (N-S).
The NS equations describe the motion of a laminar or turbulent flow, the latter when complimentary equations are added. The N-S equations must be complemented by an equation for the mass balance. This approach may be extended to more complex physical situations by considering species mixing, heat transfer and reactive flows. In the most general form used at the IEVB, the complete set of equations describing the model incorporates the following:

• mass balance equation,
• momentum balance equation (N-S equations)
• equations for turbulence closure,g
• energy balance equation,
• radiative transfer equations,
• species equations,
• global reactions closure,
• second phase equations.

The IEVB utilizes this approach for:

• calculations of turbulent ows with or without heat transfer,
• simulations of combustion of gaseous, liquid and solid fuels.

he use of mathematical modeling is of a great importance in several fields of engineering. The IEVB activities focus on the following aspects: development of mathematical models for automation and optimization of processes in industrial furnaces, CFD (Computational Fluid Dynamics) simulations of furnace used in the steel, glass, cement and ceramic industries, CFD simulation of flames of various fuels (coal, gas, oil, wood, biomass ...). The mathematical models are used to predict turbulent flows, heat transfer, mixing and pollutants emissions (CO, NOx, soot, SOx) in High temperature processes. Figure 3.6.1: Temperature eld inside a silencer of a FIAT 500 (left) and transient cooling
of a mold used in the glass industry (right)

In addition, the following IEVB modeling and validations are carried out:

• Detailed coal de-gasication and coke combustion at a high heating rate
• Simulation of turbulances in middle und high swirling ow
• Advanced tar and harmful emission chemistry
• Advanced models concerning coke burnout
• Models for slagging and pollution from industrial plants using coal and co-incineration of substitute fuels for combustion Figure 3.6.2: Particle trajectories in the coal-red boilers with color coded gas
temperatures

 Contact person: Dr.-Ing. M. Mancini

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