Axial Turbine CFD Simulation
This case study shows a complex CFD simulation of axial turbine using simulation environment TCAE
TCFD is automated workflow
Axial Turbine CFD simulation workflow is nowadays standard engineering tool. CFD SUPPORT introduces the new generation of CFD simulations. TCFD brings an extreme increase of productivity to CFD simulations. TCFD is extremely popular project, because it successfully merged benefits of an open-source (perpetual, unlimited users, jobs, and cores, customizable, …) with benefits of commercial codes (professional support, well tested, ready for the industry, robust, accurate, automated, GUI, …).
TCFD is fully automated, it can run the whole workflow by a single command: data input, new case is written down, mesh is created, case is set-up, case is simulated, results are evaluated and the results report is written down. Both GUI and batch mode. Data in – data out. TCFD is mainly focused on supporting the engineers in their real value added work. TCFD is fully automated and the beauty of TCFD is that it is the user who decides how deep to dive into a CFD or not at all. And all the options remain open at the same time.
The input data
The surface model data in .stl file format together with physical inputs are loaded in TCFD. Other option would be loading an external mesh in OpenFOAM® mesh format, or loading an MSH mesh format (Fluent mesh format). This CFD methodology employs a multi component approach, which means the model is split into a certain number of regions. In TCFD each region can have its own mesh and individual meshes comunicate via interfaces.
The Mesh
In this particular case the Axial turbine model is split into three components. The Spiral, the Impeller and the Drafttube. Each component has its own mesh. All the meshes are created automatically for each component within snappyHexMesh. Any number of model components is allowed, for example a typical Axial turbine might have a five component alternative: Spiral, Stay, Guide, Impeller and Drafttube.
In any CFD simulation, there is always big question how fine mesh is needed for ceratin level of CFD results. In rotating machinery there is usually clear trend observed: the finer mesh leads to slightly higher efficiency.
- Incompressible flow model
- Steady-state flow model
- Medium: Water
- Viscosity: ν = 8.899e-7 [m2/s]
- Flow Rate: 1 [l/s]
- Interface: AMI
- Turbulence Model: k-ω SST
- Mesh: snappyHexMesh
- Mesh Cells: 268,752
- Mesh Average y+ : 130.45 [-]
- CPU time (steady-state): 0.65 [core.hours]
Running CFD Simulation
The simulation can be run on any number of parallel processors. Immediately after the simulation is started the user can follow the progress of all the important quantities: flow rates, residuals, efficiency, torque, or pressure difference. This run-time functions give the user valuable information of the convergence and also the availability to stop the simulation before its standard end.
The workflow computes automatically complete characteristics point by point.
Every simulation performed in TCFD has its report in .html format: Axial Turbine Report Example.
Visual Postprocessing using Turbo Blade Post
The simulation results are examined in ParaView (included in any of OpenFOAM distributions). ParaView is CFD postprocessing tool providing all standard features for analyzing CFD data.
CFD Support developed special extension to ParaView for postprocessing rotating machinery: Turbo Blade Post which is special set of filters for ParaView to enable for example blade-to-blade view, or meridional average. Turbo Blade Post detailed manual is available on-line: Turbo Blade Post Manual
Within Turbo Blade Post the impeller mesh can be unwrapped to be able to slice the computed quantities of the same height along the blade. With such a unwrapped mesh it is also possible to plot quantities around the blade at the certain height.
Another Turbo Blade Post function is Meridional Average which creates a meridional plane of circumferential averages of simulated quantities.
Download TCAE Tutorial - Axial Turbine
File name: axial-turbine-stage-subsonic-TCAE-Tutorial-21.09.zip
File size: 34 MB
Tutorial Features: CFD, TCAE, TMESH, TCFD, SIMULATION, AXIAL TURBINE, TURBOMACHINERY, COMPRESSIBLE FLOW, RANS, STEADY-STATE, AUTOMATION, WORKFLOW, SINGLE BLADE, PERIODIC SEGMENT, SNAPPYHEXMESH, 2 COMPONENTS, RPM=3000