Particle Deposition Model for a Fully Developed Turbulent Channel Flow
Abstract
“Plate-out" refers to the deposition or buildup of solid material on a surface, which can have consequences such as increasing the risk of criticality or corrosion and the efficiency of equipment and systems. Current plate-out codes predicting fission products and graphite dust transport are only accessible for internal institutional use and are solely applicable to the nuclear application, despite the fact that porous particle deposition is a crucial component of many industrial heat recovery systems. The numerical findings based on the original geometry may be imprecise due to the accumulating deposition. This study aims to develop a mathematical model for particle deposition under a fully-developed turbulent flow in a rectangular channel, taking the effect of the change in geometry over time. The most significant part of the model is mathematically predicting the equilibrium thickness/mass of the deposition. Non-dimensionalization, scaling analysis, and parametric study are conducted and reported. For a fixed free stream velocity, the critical friction velocity decreases for larger particles. Critical frictional velocity is the velocity at which the deposited particles on a surface begins to lift off. For a fixed particle diameter, the critical friction velocity decreases as the free stream velocity increases. For a fixed Reynolds number Re, as the non-dimensional particle relaxation time increases, the particles take longer time to adjust themselves back to the fluid streamlines, resulting in higher possibility of being deposited on the wall. Hence, the non-dimensional deposition velocity increases with an increase in non-dimensional particle relaxation time. For a fixed Re, as particle relaxation time increases, the deposition velocity increases, resulting in more particles being deposited over a unit area and time. In general, as more particles are deposited, the surface takes less time to become saturated and approach equilibrium faster. Therefore, the saturation and equilibrium time decrease with an increase in non-dimensional particle relaxation time. For a fixed particle concentration, as the inlet velocity increases, the saturation and equilibrium time decreases, and the asymptotic deposited mass decreases.
Subject
depositionlong-duration deposition
aerosol mechanics
asymptotic deposition
saturation time
equilibrium time
Citation
Ngo, Khoi M. (2023). Particle Deposition Model for a Fully Developed Turbulent Channel Flow. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /198965.