| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 92 === Optical disk drives (ODDs) have been designed to operate faster, so as to increase the data acquisition rate. However, as the disk rotates faster, stronger vibration and noises generally are produced, which not only degrade the performance of the disk drives, but also receive complaints from the users. Of course, to solve such problems, one needs to understand the genesis and propagation mechanisms of the vibration and noises of optical disk drives. However, to date this remains to be a nontrivial engineering challenge.
An important source of optical disk drive noises is aerodynamic noise, which may result from complicated interactions between the flow and structure in an ODD. As an attempt to understand such interactions, in this thesis we analyze the flow and noise characteristics of a rotating disk, using both analytical and numerical approaches. Specifically, first we use a two-dimensional model problem to examine the influences of various possible engineering means on the acoustic field produced by a rotating disk. Based on the results, we can then assess the effectiveness of such means in the reduction of acoustic noises. Furthermore, the flow and noise characteristics of a more realistic ODD are also discussed, based on results of numerical simulations using the commercial software FloWorks®.
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