Industrial Presenter: Ferdinand Hendriks, Hitachi GST
The ability to follow data tracks in today’s fastest spinning hard disk drives is strongly
limited by high-frequency aerodynamic buffeting of the – typically non-streamlined -
arm and suspension carrying the magnetic read/write transducer. The offending displacements
are minute: of the order of a few nanometer. An effective way to combat aerodynamic
buffeting of the arm is to provide a region of low flow energy in its immediate
surroundings without much increase in the drive’s spindle power. This can be done by
diverting the airstream ahead of the arm and reintroducing it downstream from the arm in
order to conserve flow momentum (bypass approach). The air diversion process can be
enhanced with a flow diverter placed between adjacent disks. However, complete blockage
of air flow to the slider-arm region is not viable for reasons of manufacturability.
The goal of the week is to come up with efficient (high drag) shapes for the flow diverter.
Figure 1: Top: Ultrastar 15K147 disk drive. Bottom:
Comparison of pressure field for a
Ultrastar 15K147 disk drive. Notice that the pressure amplitude is lower with the
partial bypass, and the vortex shedding from the arm has been reduced. From the ISPS 2005
conference in Santa Clara, CA, in collaboration with Andre Chan.