Having performed Computational Fluid Dynamics (CFD) simulations for each component of Matthias Wandel's "Small Dust Collector," the time has come to assemble and test the entire system - virtually, of course. Recall that the main components of the dust collector are a cyclone, a filter assembly, and a blower.

Dust Collector CFD Simulation

3D Model Construction

The fully assembled model required the repositioning of the three main components and then virtual plumbing to connect them as depicted in Matthias' SketchUp assembly model.

Small Dust Collector SketchUp Model

Small Dust Collector SketchUp Model Section

First the pipes for the complete CFD model were trimmed to the required lengths. Then the final multi-volume flow-domain was created using a combination of edge lofting to create joint faces and volume stitching.

Small Dust Collector CFD Model

Performance Test

Unlike the previous CFD simulations where we had to consider a range of volume flow rates to determine the pressure drops at each condition, this test has only one operating parameter and it is fixed according to the rotation speed of the motor at 3500 RPM. The single inlet and outlet pair are assumed to be open to atmosphere, equivalent to a gauge pressure of zero.

Residuals Monitor

Summary

Recall that from our individual cyclone and filter assembly CFD simulations we found that their combined demand curves (pressure drop vs volume flow rate) intersected the blower's fan curve at a volume flow rate of 0.063 m³/s. The results for the fully assembled system indicate a volume flow rate of 0.08 m³/s.

Volume Flow Rate Monitor

Notice that there is some discrepancy in flow rate between the two CFD results for the discrete components and the fully assembled dust collector. Given that the cyclone contributes to the majority of the pressure drop through the dust collector, it is the obvious place to look for differences. It appears that the outlet location for the lone cyclone CFD analysis intersected a vortex core, whereas the cyclone exhaust piping in the assembly CFD analysis allows the vortex to dissipate and the pressure to recover. This results in a lower overall pressure drop prior to entering the filters and therefore a higher overall flow rate for the assembly.

Flow Visualization

Assembly

Pressure Iso-SurfacesDust Collector CFD Simulation

Clipped Pressure Iso-SurfacesDust Collector CFD Simulation

Velocity Iso-SurfacesDust Collector CFD Simulation

Clipped Velocity Iso-SurfacesDust Collector CFD Simulation

Components

Velocity Vectors For BlowerDust Collector CFD Simulation

Streamlines For CycloneDust Collector CFD Simulation

Pressure Iso-Surfaces For FiltersDust Collector CFD Simulation

Velocity Iso-Surfaces For FiltersDust Collector CFD Simulation

Streamlines For FiltersDust Collector CFD Simulation

Notes

The assembled geometry was created in Caedium Professional. The CFD simulation was performed using the incompressible, steady-state RANS solver with porous media, a Moving Reference Frame (MRF), and the k-omega SST turbulence model.