Decreasing Airflow Velocity in Hard Disk Drives With a Spoiler and Bypass

Ikegawa, Masahiro; Hirono, Yoshiyuki; Mukai, Hiroshi; Kaiho, Masayuki

doi:10.1109/tmag.2006.878642

Cited by 20 publications

(10 citation statements)

References 8 publications

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“…Recently Ikegawa et al [6] reported numerically (LES) that the airflow pattern changes in a HDD with the introduction of a bypass and a spoiler and confirmed the same with the help of particle image velocimetry (PIV) observations. Their analyses revealed that the introduction of spoiler decreases the flow velocity near the arm by diverting the flow into the bypass channel, and by moving the high-speed-flow area toward the inner-radius 0018-9464/$26.00 © 2009 IEEE area of the disks.…”

Section: Introductionmentioning

confidence: 69%

Flow-Induced Slider Vibration in a Functional Hard Disk Drive: Influence of Air Shroud

et al. 2009

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An air shroud is designed and placed within a commercially available hard disk drive operating at 15 000 rpm. Large eddy simulations of the turbulent airflow characteristics resulting from both the models, with and without air shroud, are carried out by assuming the read/write head is at the disk middle diameter. The numerical model consists of about nine million tetrahedral cells with the largest and smallest sizes of the cell volumes being 2.5 mm 3 and 0.35 mm 3 , respectively. The dynamic Smagorinsky-Lily model is employed to mimic the effect of small-scale eddies in the turbulent airflow. Numerically predicted airflow characteristics are compared against the LDA measurements and found to be in good agreement. The wind blowing on the surfaces of the head gimbals assembly is converted into aerodynamic forces and the resulting slider displacement in the off-track and out-of-plane directions are investigated. It is inferred that the disk drive model with air shroud results in a maximum of 44% and 10% less off-track and out-of-plane slider displacements, respectively.

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Section: Introductionmentioning

confidence: 69%

Flow-Induced Slider Vibration in a Functional Hard Disk Drive: Influence of Air Shroud

et al. 2009

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“…The result showed that the vibration of the HGA was induced by two different mechanisms; vortex-shedding (i) induced by a suspension flange of high and discrete frequency (ii) a low frequency mode induced by the E-block supporting the actuator arm. Hirono et al (2004) and Ikegawa et al (2006) studied the relation between the power consumption of the spindle motor and a spoiler's thickness and length. To measure the vibration of a Head Stack Assembly (HSA), the LDV technique was used with five partially enclosed disks rotating at 10,025 rpm.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the flow-structure interactions in an air- or helium-filled hard disk drive geometry

2011

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The increased rotating speed of the hard disk drive (HDD) causes an unsteady flow field between each stack of disks and leads to flow induced vibration on the slider suspension unit (SSU). This flow induced vibration can reduce the positioning accuracy of the SSU and lead to failure to read or write data. Therefore, reduction of turbulence kinetic energy around the SSU is an important step to improve the performance of the HDD. Several modifications have been investigated in air to decrease the direct effect of unsteady flows on the SSU (e.g. spoiler, damper, or divider in the region upstream of the arm). However, these methods are not fundamental solutions for reducing the vibrations on the SSU. Since the HDDs currently in use are filled with air, helium was selected to compare the flow pattern due to the differing inertial property. To visualize the flow pattern, particle image velocimetry (PIV) measurements were performed at the inter-disk mid-plane between a pair of disks near the arm and the SSU. The geometry is an expanded 29 model simulating Seagate cheetah 2.5-inch drive. For both the air and the helium filled drives, measurements have been performed for two different locations of the SSU for two different angular velocities of 1,000 and 3,000 rpm, corresponding to 5,000 and 15,000 rpm in the commercial drive. The results reveal that the flow patterns of the air and the helium flow are quite similar. However, with respect to the turbulence intensity around the SSU, the helium flow shows a drastic decrease compared with that of the air flow, resulting in much reduced positioning errors. As such, helium-filled drives have merit and should be looked into.

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“…However, as the length or the thickness of the spoiler increased, more power was consumed by the spindle motor. Ikegawa et al (2006) reported that the presence of a spoiler and a bypass upstream of the actuator arm reduced velocity disturbance around the slider. They visualized the flow field experimentally using PIV measurement, and also numerically using the LES technique.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the flow-structure interactions in an air- or helium-filled simulated hard disk drive

2011

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Since its invention, the Hard Disk Drive (HDD) has been the most widely-used device for data storage. Recently, the volume of data is getting larger and the corresponding rotation speed of the HDD is increasing to allow for better data transfer. The decreasing size of the disk is increasing the density of data on the disk surface. As a result, the positioning accuracy of the Suspension Slider Unit (SSU), where the magnetic head is mounted, is the problem that has to be overcome for better performance of the HDD. Additionally, the increased rotating speed of the disk induces unsteady flow between each pair of disks. This unsteady flow becomes turbulent around the SSU and induces vibrations on the SSU which deteriorate the performance of the HDD. There have been many investigations to understand the fluid mechanics phenomena inside the HDD filled with air. Additionally, many modifications have been tried to minimize the flow-induced vibration on the SSU by placing a blockage upstream of the arm to generate a low velocity region. However, none of these investigations have explored the effect of using gases other than air. In this work, the flow physics in the HDD is investigated numerically with the drive filled with air or helium. Numerical analyses were performed using the commercial code (ANSYS/CFX) with an expanded 2 9 model simulating Seagate cheetah 2.5-inch drive. Despite obvious un-addressed issues in sealing the HDD, the unsteady characteristics of the flow are dissipated sufficiently faster in helium than in air so as to warrant further studies addressing the more practical issues of working with helium. Of particular importance is the unsteady flow around the SSU. This leads to lower levels of flow-induced vibration in the case of helium flow. As such, HDD performance may be improved by using helium to improve the dynamics of the HDD at higher rotation speeds. For both air-and helium-filled drives, calculations have been performed with two different locations of the SSU and two different angular velocities, 1,000 and 3,000 rpm corresponding to 5,000 and 15,000 rpm in 3.5-inch commercial drive. Not only is it shown that the helium-filled drive suffers lower positioning errors, but also the underlying flow physics responsible for such improvement are explained.

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Decreasing Airflow Velocity in Hard Disk Drives With a Spoiler and Bypass

Cited by 20 publications

References 8 publications

Flow-Induced Slider Vibration in a Functional Hard Disk Drive: Influence of Air Shroud

Flow-Induced Slider Vibration in a Functional Hard Disk Drive: Influence of Air Shroud

Experimental study of the flow-structure interactions in an air- or helium-filled hard disk drive geometry

Numerical study of the flow-structure interactions in an air- or helium-filled simulated hard disk drive

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