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Title: Particle diffusion in a turbulent air jet
Author: Salih, Sabir Mohamed
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1977
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In this work, an experimental apparatus is designed to produce a solid particle-laden, round, free air jet. It was tested for axisymmetry and similarity of the velocity profiles, its pivot-tube and a hot wire anemometer and the results confirmed measurements by previous investigators. The apparatus was also tested with particles and found to perform within the design limits. A laser-Doppler anemometer (LDP) Was used in the real-fringe forward-scattering mode to determine the size of the particles used and the result was verified by photomicrography. The LDA burst signal visibility was related to the number of scattering centres in the probe volume by Farmer (1972). This relationship was used to measure the number of particles at radial positions across the jet relative to that at the centre-line. Firstly, the visibility was measured directly from a storage oscilloscope trace and secondly, an electronic signal processing technique was developed. Measurements for titanium dioxide particles, which are expected to follow closely the fluid flow, were found to agree quite well with the classical results of heat and tracer-gas diffusion. Measurements with tungsten metal particles, which are heavy and so their inertia is expected to resist diffusion, were in broad agreement with theoretical predictions. The analytical result was obtained from a numerical solution of the theory developed by Davidson and HcComb (1975). This theory, which is for monodisperse particles, was derived in detail and a crude generalisation to the case of polydisperse particles was then given.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available