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THETA Code

Computed velocity distribution and streaklines in a semi-technical combustion chamber

Numerical simulation of ignition processes in multi-phase flows.

Large eddy simulation (LES) of a swirl flame

The DLR in house code THETA (Turbulent Heat Release Extension of the TAU Code) was developed to simulate flow and chemical reaction in combustion chambers. The THETA code was created in collaboration with the DLR Institute for Aerodynamics and Flow Technology on the basis of the compressible DLR code ‘TAU’ and is under continuous development in various research projects. It provides a platform for developing and validating new numerical computation methods as well as physico-chemical models for computing combustion chamber flows.

The main features of the code are:

• 3D finite volume discretisation on unstructured dual grids
• An interface with which any number of additional transport equations can be predetermined and defined
• Automatic grid adaptation
• Pressure-based solution algorithm: SIMPLE, fast projection method
• Compressible fractional step multiscale solver and acoustic boundary conditions for acoustics simulation in combustors
• Linear equation solvers: BiCGStab, GMRES, CGS with/without LDU decomposition, multigrid acceleration
• Solver for stiff chemistry
• Region-based parallelisation
• High and low Reynold number k-ε, k-ω and k-ω-SST turbulence models
• Four-equation model for turbulent scalar transport
• LES/RANS turbulence models
• Combustion models:
  • Flame sheet, EDC, EDC/FRC
  • Flamelet-PDF, TFC
  • Complex (detailed) chemistry with multivariate assumed JPDF model
• Detailed soot and soot precursor model
• Lagrangian/Eulerian multiphase model (SPRAYSIM)