The aim of this study was to examine a fully turbulent, particle laden flow in a square duct. Velocities were measured by particle image velocimetry, using both direct beam and fibre optic illumination systems. Small bubbles of diameter approximately 2<i>μm </i>(density~1.2<i>K g m</i><sup> -3</sup>) were used as seeding, and three sizes of large glass particles, with diameters of 59±51<i>μm, </i>173±53<i>μm, </i>and<i> </i>471±120<i>μm </i>(density=2500<i>K g m</i><sup> -3</sup>), were introduced into the flow. Measurements were obtained for all four particle sizes within five parallel planes, and from these results mean flow profiles, turbulent stresses and spectra, and concentration profiles were all examined. The results compared well with the simulations and experiments of other authors, and where such comparison was not possible some interesting trends were observed. In fully developed turbulent flow in a square pipe there are eight spanwise circulation cells, which move fluid away from the walls along the midwall bisectors and then back into the corners. It was possible to accurately estimate how much the spanwise velocity of the glass particles would lag that of the fluid, using empirical data and an approximate form of Stokes law. The glass particles were also found to have a relatively slow streamwise velocity in the centre of the circulation cells.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:643363 |
| Date | January 2002 |
| Creators | Coltman, Scott Stuart |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13448 |
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