CFD DEM Modelling of a Cyclone Separator
Altair EmployeeA cyclone separator is a mechanical device that uses the principle of centrifugal force to remove particulates from air, gas or liquid stream without the use of filters. It is often employed in industrial processes to separate dust or other unwanted materials from fluid streams efficiently.
Modelling these systems helps in identifying bottlenecks such as recirculation zones that may reduce performance. These models can also help calculate the particle removal efficiency, which can help ensure compliance of these systems with environmental regulations for emissions.
Altair provides solutions to model these using a very high-fidelity DEM tool called EDEM, coupled with a general purpose CFD solver called AcuSolve.
The simulation files (both EDEM and AcuSolve) can be found in the attachments.
The key steps to setup a CFD-DEM model of a cyclone separator are:
Step 1: Setup the EDEM model
Import the CAD into EDEM, and add materials for the CAD geometry and the particles. Define the particle shape, and create a factory to introduce the particles into the simulation domain at a set target mass flow rate.
You can check the complete setup of the EDEM model in the attachments.
Step 2: CFD mesh generation and boundary conditions
CFD generally requires volumes to do its analysis on, so please make sure to fill the cyclone separator domain to make it a volume instead of a shell part, before importing.
Once the CAD is imported, mesh the CFD volume.
The yellow face has the ‘inlet’ boundary condition, the purple face has the ‘outlet’ boundary condition. The green faces have ‘wall’ boundary conditions on them.
Step 3: Setup the CFD solution
The CFD material definition not only contains the fluid and particle definition, but also contains the lift, drag and torque models to be used. Since the dust particles in this case are spherical in shape, spherical drag models can be employed.
The timestep and the turbulence model needs to be set. Make sure the CFD timestep is an integer multiple of the DEM timestep.
Finally, if SimLab is being used for pre-processing, make sure to choose the ‘h3d’ output file format in ‘Result Request’, so that you can visualize the results within HyperView. If HypermeshCFD is being used for pre-processing, you can convert the results log file into the ‘h3d’ file format using the ‘Convert’ option. From HyperView 2024.0, only h3d results will be read by HyperView, and log files from AcuSolve will not be read. However, log files can be used for post-processing within HypermeshCFD.
Step 4: Run the coupled simulation
Once both solutions are prepared, make sure to start the ‘Coupling Server’ within EDEM, before running the CFD problem. The CFD solver drives the DEM/coupled solution.
Step 5: Visualize the results
You can visualize the DEM results within EDEM Analyst.
To visualize the coupled solution results, you can use HyperView. Remember to load the .dem file (for EDEM results) before the h3d file (for AcuSolve results). Also, make sure to select the ‘Overlay’ button to ensure that both results are overlaid on each other, and both results are visualized together.
A CFD-DEM coupled simulation like the above can help predict the separation efficiency for different particle sizes and densities, ensuring the separator meets desired performance criteria.
Such models can help estimate the pressure drop across the separator also, which directly impacts energy consumption and operational costs. These models also help evaluate how the cyclone integrates with upstream and downstream processes. These evaluations can be used to improve the chamber design and the inlet/outlet configurations.