Digital image processing is a technologically limited subject, and has seen tremendous growth over the last ten years with the exponential increase in computing power commonly available. This tend can be seen in Particle Image Velocimetry (PIV) as the migration from traditional wet film cameras to fully digital systems. The use of digital cameras in PIV measurements has been commonplace for a number of years. However, the majority of the reported systems suffered from low spatial and temporal resolution due to the architecture of commonly available cameras. The aim of this thesis was to construct a system which was entirely digital, with high spatial resolution and flexible timing abilities, removing the need to use image shifting. In order to create such a system, a state of the art in digital imaging technology was reviewed. The conclusion of this study was that in order to achieve the aims set, a multiple CCD (Charge Coupled Device) system would be required. The prototyping and construction of both two- and four-CCD array cameras is described. The software required to analyse images from low spatial resolution sources (relative to film) is also described, including the precautions that must be taken to ensure unbiased and accurate velocity measurements. Finally, the multiple CCD-array systems were applied to a number of flows to prove the concept. These include the study of breaking waves, wave motion over submerged pipes, and extension of the PIV technique to enable the measurement of accelerations.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649502 |
| Date | January 1998 |
| Creators | Dewhirst, Timothy Peter |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13637 |
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