Unsteady analysis and experimental verification of the aerodynamic vibration mechanism of HDD arms

Tsuda, N.; Kubotera, H.; Tatewaki, M.; Noda, Shigeho; Hashiguchi, M.; Maruyama, Takuya

doi:10.1109/tmag.2003.808931

Cited by 28 publications

(16 citation statements)

References 5 publications

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“…Kubotera et al [9] and Tsuda et al [10] have proven that the presence of a weight-saving hole in a HDD arm creates a larger 3D spiral vortex downstream of the arm and a negative aerodynamic disturbance torque. Gross [11] showed the effect of the thickness of the E-block arm on airflow and subsequently on the FIV on the sliders.…”

Section: Past Work On Hdd's a Flow-induced Vibration (Fiv)mentioning

confidence: 99%

Structure Optimization Study of Hard Disk Drives to Reduce Flow- Induced Vibration

Ng¹

2011

TONUMJ

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Abstract:In this paper, the effects of two flow-induced vibration (FIV) mitigation components on hard disk drive (HDD) airflow, vortex splitters and flow diverters, were verified. The edges of the components were also modified by filleting and the resulting effect on airflow determined. A perspective review on HDDs and their operation, and the mechanism and mitigation of FIV was discussed. Three suitable turbulent models from the commercial fluid flow solver FLUENT were briefly compared. A preliminary study was then carried out on a simplified HDD model to determine the mesh fineness required in HDD turbulent flow simulation in order to obtain accurate results. Another study was done to compare between the RNG k-and LES turbulent models in FLUENT. A full 3.5 inch commercial HDD model was used and results indicated that the LES model was suitable for turbulent flow modelling of a HDD. Lastly, flow simulation of three HDD models with different FIV mitigating features was carried out. Results showed that flow diverters are effective in reducing airflow turbulence in HDD for Re of 12.5x10 4 . The modification and filleting of component edges to make them more aerodynamic streamlining was shown to be less effective but further studies should be done to conclude on the effectiveness of filleting. An optimized HDD structure which includes both vortex splitters and flow diverters, with the filleting of component edges recommended but not mandatory was proposed.

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Section: Past Work On Hdd's a Flow-induced Vibration (Fiv)mentioning

confidence: 99%

Structure Optimization Study of Hard Disk Drives to Reduce Flow- Induced Vibration

Ng¹

2011

TONUMJ

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“…Here, there are two turbulence-related issues that need to be tackled: (i) vibration of the platters, and (ii) vibration of the heads. Studies on the air flow pattern within disk drives [28,10] show that there is turbulence in a region surrounding the head, but the gap flow reverts to laminar beyond that region. By placing the arm assemblies diagonally from each other (as shown in Figure 1), the vibration of the platter due to the second arm will be at most additive (i.e., the effects of the two heads will be independent of each other, and the total is at most twice larger), and the heads on the respective arm assemblies will not affect each other either.…”

Section: Issues In Implementing Intra-disk Parallel Drivesmentioning

confidence: 99%

Intra-disk Parallelism: An Idea Whose Time Has Come

Sankar

Gurumurthi

Stan

2008

2008 International Symposium on Computer Architecture

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Power is a big problem in data centers and a significant fraction of this power is consumed by the storage system. Server storage systems use a large number of disks to achieve high performance, which increases their power consumption. In this paper, we propose to significantly reduce the power consumed by the storage system via intra-disk parallelism, wherein disk drives can exploit parallelism in the I/O request stream. Intra-disk parallelism can facilitate replacing a large disk array with a smaller one, using the minimum number of disk drives needed to satisfy the capacity requirements. We show that the design space of intra-disk parallelism is large and present a taxonomy to formulate specific implementations within this space. Using a set of commercial workloads, we perform a limit study to identify the key performance bottlenecks that arise when we replace a storage array that is tuned to provide high performance with a single high-capacity disk drive. These are the bottlenecks that intra-disk parallelism would need to alleviate. We then explore a particular intra-disk parallelism approach, where a disk is equipped with multiple arm assemblies that can be independently controlled, and evaluate three disk drive designs that embody this form of parallelism. We show that it is possible to match, and even surpass, the performance of a storage array for these workloads by using a single disk drive of sufficient capacity that exploits intra-disk parallelism, while significantly reducing the power consumed by the storage system compared to the multi-disk configuration. We evaluate the performance and power consumption of disk arrays composed of intra-disk parallel drives, discuss the engineering issues involved in implementing such drives, and finally provide a preliminary cost-benefit analysis of building and deploying intra-disk parallel drives, using cost data obtained from several companies in the disk drive industry.

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“…Tsuda et al [18] report DNS results, while Tatewaki et al [19] report LES results of airflows in realistic disk drives.…”

Section: A Prior Researchmentioning

confidence: 99%

A Study on the Efficacy of Flow Mitigation Devices in Hard Disk Drives

Kirpekar

Bogy

2006

IEEE Trans. Magn.

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We report on large eddy simulations of the turbulent flow of air in hard disk drives (HDDs) using a commercial CFD code. In particular, we focus on HDD casings in which flow-induced vibrations are reportedly reduced by small geometrical modifications. The modifications investigated are M1: a blocking plate situated between the disks, M2: a spoiler (or deflector) located behind (downstream of) the actuator arm, and M3: a similar deflector upstream of the arm. We observed that M1, M2, and M3 significantly modify the mean flow patterns in the drives. M1 reduces velocity magnitudes in most parts of the drive, the modification of M2 causes flow reversal in regions close to the hub, while M3 causes the shedding of vortices upstream of the actuator arm. Our analysis points to M1 as the best candidate for mitigating the effects of turbulent airflow. This is because M1 is more effective in reducing the root-mean-square velocity fluctuations near the suspension. M1 is also more effective in reducing the pressure fluctuations near the base-plate and suspension region. This reduction, however, is at the cost of approximately 20% higher windage. Finally, we note that M3 has the adverse effects of increasing velocity and pressure fluctuations and hence is not the ideal candidate for mitigating airflow effects, among the modifications considered here.

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Unsteady analysis and experimental verification of the aerodynamic vibration mechanism of HDD arms

Cited by 28 publications

References 5 publications

Structure Optimization Study of Hard Disk Drives to Reduce Flow- Induced Vibration

Structure Optimization Study of Hard Disk Drives to Reduce Flow- Induced Vibration

Intra-disk Parallelism: An Idea Whose Time Has Come

A Study on the Efficacy of Flow Mitigation Devices in Hard Disk Drives

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