Grid generation using G3DHexa

G3DHexa is a structured 3D multiblock mesher for the generation of high quality grids for CFD applica-tions in turbomachines.The software package G3DHexa has been used in DLR since 2001 and has been successively improved and extended in terms of various geometry application

S1 block topology for compessors (OCH) and turbines (OCGH) . S1 Clearance topology options (H2, OH) . 3D grid: Tubine stage with sidewall contouring (CAD) . 3D grid: Radial compressor splitter impeller (CH)

aspects.As a pre-processing tool the grid generator is strongly coupled with the DLR flow solver TRACE. G3DHexa is also used for mesh generation at a large number of national universities.In the German turbomachine industry G3DHexa has, since 2001, been integrated in the design process for compressors and turbines at MTU Aero Engines in Munich.The most important features of the grid generator are as follows :

• Template based
• 2D meshing of the meridional flow path (S2m)
• 3D package for compressors as well as for linear compressor cascades (Fig. 1)
• 3D package for turbines and linear turbine cascades (Fig. 1, Fig. 2)
• Applicable for different blade shapes: rounded, cusp, blunt leading and trailing edges, blade fillets
• Optionally different hub and tip clearance topologies (full and semi-clearance, Fig. 2)
• Meshing based on CAD geometry input (fillets, sidewall contouring)
• 3D grid generation for multi-passage geometries (splitter, mistuning, etc.)
• 3D meshing for aeroengine inlet regions as well as for axis-symmetric ducts (segment, full anullus)
• 3D grids for radial compressor impellers with large fillets and blunt trailing edges
        (splitter blade option, Fig. 4)
• Semi-automatic version in the course of a geometry optimisation process

Of what use is the best flow solver without the appropriate post-processing?

POST is a block-parallelized post-processing-tool developed especially to analyze multi-stage turbomachinery components. The applications range from the calculation of 3D field variables over averaged 2D- and 1D-distrubitions to global indicators and ratios of the turbomachine. The core

Schlieren at 85% cannel height at UHBR-fan . Pressure at two S3-planes at UHBR-fan . Circumferential averaged Mach number in the UHBR-fan . Radial distribution of the pressure upstream and downstream of the rotor of the UHBR-fanBildunterschrift

item and main application of POST is the general analyses of turbomachines. It is composed of circumferential averaged radial distributions, blade distributions as well as global performance values like the efficiency factor for the whole component. POST is able to process both steady and unsteady data sets.

Because POST is used for research purposes as well for the industrial design process, it is designed in a modular manner and can be easily adapted or extended by the users to fit their requirements.

• Flexible and extendable analysis of TRACE-simulations
  • Comparisons between different flow solutions and geometries
  • Processing of unsteady data (hamonics and time sequences)
  • Analysis on user-defined planes
  • Calculation of derived variables with user-defined specifications
  • Analyses of turbomachines on steady flow data
  • S1, S3 plane analyses
  • S2m, radial distributions
  • Parallel output
• Consideration of e.g. radial compressor, splitter, end wall contouring, …
  TRACE-conform flux calculation, metricies, …
  Runtime reduction with
  • Data reduction
  • Reduction of file accesses
• Easy to use command line interface
• Simple interface for developer
  • Custom-made „Tasks“
  • Modular components of an analysis
  • Basis for user-defined calculations
  • Programmable in C without the use of POST source code
  • Automated integration
  • Integrates, automatied help system