Aerodynamic Pressure Fluctuations Associated With Flow-Induced Vibration of the Head Gimbals Assembly Inside a Hard Disk Drive

This paper presents an experimental investigation and numerical simulation on the spectrum-spatial characteristics of aerodynamic pressure fluctuations around the head gimbals assembly (HGA) in a working hard disk drive (HDD). The pressure fluctuations are measured through tiny holes on the HDD top cover above the HGA. The positioning error signal and servo system sensitivity in the working HDD are measured as well to evaluate the slider off-track vibration. Comparisons between the spectra of pressure fluctuations and the slider off-track vibration show that, the pressure fluctuations around the HGA are highly associated with the slider off-track vibration in terms of principal peaks in the spectra, especially at 1.83 kHz and 2.54 kHz. The results also show that the spatial coherence of pressure fluctuation around the HGA remains high at frequencies around the principal peaks in the spectra, which has been further confirmed by the numerical simulation based on a two-dimensional large eddy simulation model. It is concluded that the flow-induced HGA vibrations in an HDD can be detected and evaluated through the pressure fluctuations by a sensor around the HGA.