Experimental and numerical study of the flow in a simulated hard disk drive

With increases in the recording density and rotation speed of hard disk drives (HDDs), the aerodynamic aspect of drive operation now has a significant impact on the design of storage systems. The increasing areal density requires improving the positioning accuracy of the magnetic head whereas the increasing rotational disk speed generates a strong unstable airflow inside the drive, causing vibrations of the disks and the suspensions/magnetic heads. These vibrations, especially for the suspensions, have a considerable effect on head positioning accuracy that can result in read/write failure of the drive.; In order to have a better understanding of the aerodynamics phenomena occurring in a hard disk drive, a simulated device was designed at a scale close to 2:1 in order to investigate the airflow experimentally. The experimental apparatus has a simplified geometry but remains realistic and is composed of only two corotating disks and a pair of suspensions/slider units (SSUs). Between them, Particle Image Velocimetry (PIV) and Hot Wire Anemometry (HWA) were performed in the midplane between the two disks and the two suspensions. Additional PIV measurements were performed at a second plane and are described in this study.; The experimental measurements were used to guide and test a numerical procedure for calculating this class of flows. The data are used both to set the necessary boundary conditions and to validate the field results obtained. The numerical procedure gives temporal and spatial information on a three dimensional wedge-like domain. A quantitative assessment of the numerical approach based on a comparison of experimental and computed data is included. Both sets of results can be used to guide future research on the internal fluid mechanics and flow-driven vibrations of structures within hard disk drives.; Both experimental and numerical investigations reveal a number of aerodynamic sources potentially capable of driving flow-induced suspensions/sliders vibrations which should be minimized in improved hard disk drive designs.