Topology optimization of actuator arms in hard disk drives. Pdf comparison of actuator disc flows representing wind. A comparison of actuator disk and actuator line wind turbine models and best practices for their use conference paper pdf available january 2012 with 1,835 reads how we measure reads. For lowspeed flows, actuator disk flutter models have been able to predict the onset of.
The flow field around a wind turbine rotor is very complex. The general methods developed using actuatordisc theory are used to calculate the flow through the model stage and are compared with raillys theory, and with radial equilibrium solutions. Some actuatordisc theories for the flow of air through an. Finite element analysis of diskspindle vibration in hard. Actuator disc theory has been further developed to model the influence of density gradients upon the meridional flow through multistage turbomachines. Design and dynamics of flying height control slider with piezoelectric nanoactuator in hard disk drives to achieve the areal density goal in hard disk drives of 1 tbitin. Older hard drives used a stepper motor actuator, which moved the heads based on a motor reacting to stepper pulses. Many portable devices such as laptops, tablets, and music players prefer the data storage with higher capacity while its size needs to be smaller.
It is automatically recognized by the upper side tool at the time of configuration. Pdf joukowsky actuator disc momentum theory researchgate. The main difference between rankine and froude theories is in the treatment of the rotor disk as a series of elementary rings, versus the treatment of the disk as a whole. Media in category actuator disk theory the following 18 files are in this category, out of 18 total. In fluid dynamics, the momentum theory or disk actuator theory is a theory describing a mathematical model of an ideal actuator disk, such as a propeller or helicopter rotor, by w. The platters rotate when the hard disk is performing readwrite operations. Rankine 1865, alfred george greenhill 1888 and robert edmund froude wikidata 1889 the rotor is modeled as an infinitely thin disc, inducing a constant velocity along the axis of rotation. Pdf validation of an actuator disk model for numerical. Modern hard drives use a voice coil actuator, which controls the movement of a coil toward or. Determination of wind turbine far wake using actuator disk rodeyna amer, ivan dobrev, fawaz massouh to cite this version. Bcdat file in zen result in high gradients of flow field variables around the. I would like to add the actuator disk in my flow field.
Introduction mathematical models were developed to predict vibration of a diskspindle system for hard disk drives hdd 1, 2, 3, and 4. Hard disk drive, trackfollowing control, quantitative feedback, robust control. Actuator disc methods applied to wind turbines dtu orbit. Bending flutter in axialflow compressor by actuator disk. The sectional load is calculated with the blade element theory for a propeller of a sailplaine with a folding engine and the actuator disk is applied to investigate the effect of the jet to the elevator.
Actuator disc methods applied to wind turbines by robert mikkelsen dissertation submitted to the technical university of denmark in partial fulllment of the requirements for the degree of doctor of philosophy in mechanical engineering fluid mechanics department of mechanical engineering technical university of denmark june, 2003. For example, my problem is that the flow is passed the actuator disk and then the total engergy of the main. Publishers pdf, also known as version of record includes final. It has been used in many studies in order to analyse and validate the momentum theory. This thesis concerns the axisymmetric actuator disc model and its extension to a three di.
Actuator disc theory is the basis for most rotor design methods, be it with many extensions and engineering rules added to make it a wellestablished method. Abstract p ermanen t magnet pm motors are to da y regarded as an in teresting solution for a wide range of in v erterfed v ariablesp eed driv es. To understand more about the performance of propellers, and to relate this performance to simple design parameters, we will apply actuator disk theory. Barasch s, chen y 1972 on the vibration of a rotating disk. The positions of the actuator planes are illustrated in figs.
In our streamtube we have fluid flowing from left to right, and an actuator disk that. All the heads are attached to a single head actuator, also called an actuator arm, that moves the heads around the platters. Download the newest pdf files or request printed catalogs and brochures by mail. Trit aemd9905 issn11020172 this do cumen tw as prepared using l a t e x2. Thrust loading and velocity are uniform over the disk.
As the recording track density increases in harddisk drives, the offtrack errorrejection capability of the servo controller must also be increased. Define file l18r32ru1ireclr 236t33tu1irec2r 3lr320tueirec3t. If you are using omron nj series, beckhoff made twincat 2 as a superordinator, download the esi file of each ver. On the limitations of froudes actuator disc concept.
Pdf actuator disc theory is the basis for most rotor design methods, be it with many extensions and engineering rules added to make it a. Servo experiments for modeling of actuator and windage. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. We model the flow through the propeller as shown in figure 7. Seagate is now floating the idea of multiple actuators in a single disk drive.
Disk drive with multiple actuators on a single axis having. Pdf a comparison of actuator disk and actuator line wind. Actuator disc theory is the basis for rotor design and analysis, valid for discs representing wind turbine rotors as well as propellers. The part of a hard disk to which the readwrite arms attaches. Blade element momentum theory is a theory that combines both blade element theory and. A hard disk drive hdd, hard disk, hard drive, or fixed disk is an electromechanical data storage device that uses magnetic storage to store and retrieve digital data using one or more rigid rapidly rotating platters coated with magnetic material.
The increasing importance of nonclassical propeller theory over the. Tels, voor een commissie aangewezen door het college van dekanen, in het openbaar te verdedigen op vrijdag 8 februari om 16. Actuator disk theory applications include propellers,rotors and ducted fans. If a file is small enough, it will be placed in a single track. For example, the motor in a washing machine can be controlled by a computer it is. These components include the platter, the spindle, head, actuator arm, actuator axis, power connector, jumper block, ide connector, and the actuator. In our first investigation of a nonlinear actuator disk theory ref. A comparison of actuator disc and bem models in cfd. These models successfully explain the vibration phenomena in hdd as follows. This means that they need to be connected to the computer using a digitaltoanalogue convertor dac motors can provide movement. It is often made of aluminum, glass substrate or ceramic. Modelling an actuator disk in fluent im having an awful lot of trouble with this, and im hoping i can get some help. We model the flow through the propeller as shown in figure 11.
Delft university of technology momentum theory of joukowsky. P286 p288 p289 disk translators bimorph piezo actuators with high dynamics. Magnetic hard disk drives comprise the primary means of storing programs and data for modern computer systems, ranging from very high performance main frame computer systems, to small notebook pcs. Pdf theoretical performance estimation of shroudedtwinrotor. Cfd actuator disk solutions for a helicopter rotor in. Since our ethercat module uses multiple vers, esi files of multiple ver are posted. Conner actually patented a hard drive design that utilized dual actuators, that is, a hard drive with two sets of readwrite units. Platters or discs made of aluminum alloy coated with a magnetic medium stores the data in magnetic patterns each platter disc is divided into tracks the tracks have circular shapes around the center spindle and are grouped into cylinders the cylinders are divided into sectors of 512 bytes each. Developments of actuator disc theory for compressible flow. Ahard disk drive dualstage actuatorwith a piezoelectric microactuator throughoutthis paper, wewill refer to the combinedvcmandeblock assembly as vcmactuator and the combinedpzt and suspension assembly as pzt actuator. Im trying to model an actuator disk in fluent, so i.
The blades of todays utilityscale wind turbines are equipped with various airfoils that are optimized to perform at their respective position along the blade span. The theory was developed further by froude 1889 and betz 1920. Marine power project froudes momentum theory for an. Determination of wind turbine far wake using actuator disk. The effects of flow separation are included in the model through rotorloss and deviationangle corre lations. The concept of actuator disk is just the disk that has no thickness. Armed with the following assumptions consider an ideal rotor as shown below. On the limitations of froudes actuator disc concept technische. A hard disk drive contains several platters that are mounted on the same spindle. What links here related changes upload file special pages permanent. We further assume that the actuator disk be stationary no rotation and that the uniform wind entering the streamtube does not change in time steady. Let us summarize the assumptions the actuator disk model.
A computer hard disk has many different components. The disk drives used are always designed to comprise the best compromise between size, performance, capacity and cost for the specific application. Froudes actuator disk theory provides a simple, 1dimensional approach to the problem of rotor modelling. Nonlinear tracking control for a hard disk dualstage. The analysis takes advantage of previous solutions for the flow induced by source discs and the analogy between compressible flows and incompressible flows with source distributions. Our se199 center of gravity measurement instrument is ideal for measuring the center of gravity of hard drive actuator arms in two axes in a. The high rejection capability is achieved by increasing the servo bandwidth. In the ideal case, the blocks of a file are contiguous on disk.
In froudes momentum theory swirl is absent, in joukowskys. Poor braking clean braking poor braking clean braking. Some toms hardware readers may remember the company. Vibration, finite element, diskspindle, hard disk drive. This approach is called momentum theory, and was first developed by rankine 1865 for marine propellers. An investigation in actuator disc cfd solution applicabillity for. The load of the disk is calculated by time averaging the sectional load of a rotating blade. The actuator disk theory can be combined with blade element theory to relate the load distribution along the blades to the propeller geometry for specified operating conditions.
Design and dynamics of flying height control slider with. All of these accessories to the computer hard disk are necessary in. Theoretical performance estimation of shroudedtwinrotor wind turbines using the actuator disk theory. Actuators are used extensively in computer control systems.
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