Comparative study on the complex behaviour of flow fields in a transparent non-axisymmetric corotating system between two arm-insertion angles at two measurement planes in an enclosure

Abstract

Flow driven by co-rotating disks, such as hard disk drives (HDD) have been studied in previous research using axisymmetric models. In our work, a unique non-axisymmetric 3.5" transparent HDD model for information storage was used to investigate the effect of the arm insertion angle on these flow-fields. After introducing the shroud opening region in our model, we focused and illustrated the nature of flow-fields at a parameter α , defined as the arm insertion angle. Comparison was made between α = 20° closer to the shroud opening and a deeper angle of α = 44° closer to the hub. We revealed the flow pattern at the disk-to-disk middle plane (mid-plane) as well as between the arm and the upper disk boundary layer (arm-upper disk plane) across the disk region from the edge of the hub to the edge of the disk, using both flow visualisation and particle image velocimetry (PIV). The visualisation results revealed an accelerated flow around the hub downstream of the arm insertion, with a higher magnitude at α = 44° compared to α = 20°. We observed a rigid body rotation around the hub for both insertion angles.

Keywords

• rotating flow
• vortex motion
• flow visualisation
• refractive index matching
• particle image velocimetry