This research aimed to investigate experimentally the effect of particle shape on air-particle flow fields. The dynamics of streams of free falling irregular particles was observed by means of Particle Image Velocimetry and Laser Doppler Anemometry. Glass crushed beads and glass spherical particles with mean diameters varying from 60 to 300 μm were employed in the measurements, yielding particle Reynolds numbers between 1 and 70. Results on the particle-particle interaction and air-particle interaction mechanisms have been attained for both dilute and dense particle streams. Significant differences between the behaviour of irregular particles and spherical particles have been found in terms of spatial velocity distribution, terminal velocity, fluctuation velocity and turbulent energy content of the gas phase. The velocity of the gas phase. The velocity of the particles in the stream was higher than the predicted single particle velocity at the flow centreline and converged towards it at the stream edges in all experimental conditions. Irregular particles exhibited a velocity consistently lower than that of spherical particles and the stream of irregular particles was characterised by a larger radius. The velocity profile of the particle stream was load-dependent with the maximum velocity moving outwards from the stream centreline with increasing mass flow rate. The particle concentration was revealed to have an important effect on the velocity of the particle stream and the generation of turbulence. In the case of a dense particle stream, the turbulent energy content of the gas phase in the presence of irregular particles was significantly reduced than in the presence of spherical particles at both low and high frequencies.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:654040 |
| Date | January 2004 |
| Creators | Losenno, Cinzia G. R. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12465 |
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