Date of Award

2016

Degree Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

First Advisor

Defoe, Jeff

Second Advisor

Rankin, Gary

Keywords

Advanced dust deposition model, Discrete Phase Modeling, Dust Deposition, Dust Deposition Measurement, Redesign, User Defined Function

Rights

CC BY-NC-ND 4.0

Abstract

High concentrations of particulate matter in air lead to deposition in critical areas of fluid flow devices involving direct intake from the environment. Dust deposition in critical areas can hamper the performance of such devices. In this thesis, the mechanism which results in dust deposition is investigated by studying and redesigning a self-actuated pressure sealing valve using two computational approaches and experiments. A simplified numerical approach is used which predicts dust deposition by employing the built-in functions of Discrete Phase Modelling (DPM) in the commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent 15.0. Also, an advanced numerical approach is used which links a user defined function (C code) to modify the built-in functions; this enables prediction of particle deposition within 15% with an 80% confidence level. Experiments are conducted to assess the dust deposition patterns and valve performance relative to the device specifications. The numerical and experimental results are utilized together to gain insight into the particle deposition behaviour. This is made possible by the development of an innovative post-processing technique that non-destructively quantifies the dust deposited in experiments without the need for any expensive equipment. A simplified 90 degree bend geometry is used to experimentally calibrate the advanced deposition model. The main mechanism responsible for dust deposition has been determined to be related to particle impact velocities and angles. Particles impacting a surface at low velocity and angle are more likely to stop. Using this insight, the valve geometry is modified to reduce the dust deposition in critical areas. In the modified design, leakage flow is reduced by up to 93% while still maintaining a positive performance margin relative to specifications.

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