Flow Visualization and PIV Analysis of Rotating Flow in Simplified HDD Model with Arm Isolation Angle Inclined at 32° Between Disk and Shroud Opening Region

Abstract

In non- axisymmetric hard disk drive (HDD), the flow must go through narrow spaces in between the disks and the arm thereby obstructing the positioning of the read and write arm which is responsible for data sensing. Using a model 2.25 the actual size of 3.5-inch HDD, we compared the flow fields between two intermediate planes in-between the disks and the arm and three mid-planes within the arm, in cylindrical coordinate fixed at a parameter α = 32°, defined as the arm isolation angle which separate the flow between the disk and the shroud opening region. We recorded and analyzed the qualitative flow visualization using a high-speed camera with different resolutions at these planes and revealed their statistical distribution using quantitative particle image velocimetry (PIV) analysis methods. Our methods revealed the radial (v_r) and circumferential velocities (v_θ) normalized by the local disk angular velocity (rΩ) around the arm as it relates to the flow from the disk and after the arm as it affects the flow from the shroud opening region. The results confirmed the irregular flow relating to the arm, disks and shroud opening region which has an immense effect on the rigid body rotation around the hub.