UVM Theses and Dissertations
Format:
Online
Author:
Vachon, Nicholas M.
Dept./Program:
Mechanical Engineering
Year:
2013
Degree:
PhD
Abstract:
Dust mitigation is an integral issue faced by numerous extraterrestrial activities. This problem is particularly challenging in Lunar and Martian environments which produce electrically charged particles that easily adhere to exposed surfaces. In this work, bound vortex flow is investigated as a means for enhanced, localized, and controlled dust particle removal in space applications where particle scatter is unacceptable. Using the techniques of computational fluid dynamic simulations, the effectiveness of vortex-induced flow conditions is evaluated by visualization of pathlines and measurement of shear stress on the impinged surface. Bound vortex characteristics have been examined under steady and pulsatile flow conditions for various operating pressures and nozzle configurations. It is found that an optimal range of key geometric and pressure parameters exist in the creation of bound vortex flow and such flow maximizes surface shear stress, thus leading to enhanced dust removal. A set of operating conditions are recreated experimentally to visualize particle removal and support computational results. The effectiveness of vortex-induced flow conditions is evaluated using a combination of high speed flow visualization, and particle image velocimetry techniques. Experimental evaluation of particle removal behavior and bound vortex formation are found to be in good agreement with nurmerical predictions.
The bound vortex concept has also been investigated as a means for enhancing surface heat and/or mass transfer. As many manufacturing and mechanical processes depend upon efficient convective heat and/or mass transfer, the bound vortex concept features potential for terrestrial applications. The use of bound vortex impingement is shown to provide intense, localized, and well controlled heat and mass transfer enhancement. The work presented investigates the influence of bound vortex flow on the mass transfer from an impinged surface over a range of flow conditions. Naphthalene sublimations techniques are employed to capture local mass transfer distributions. Experimental flow conditions are recreated computationally and the heat transfer results. Peak and average surface heat transfer values are used to determine possible mass and heat transfer enhancement. It is concluded that the addition of bound vortex flow significantly increases mass and heat transfer enhancement from an impinged surface while maintaining advantageous compact flow characteristics.
The bound vortex concept has also been investigated as a means for enhancing surface heat and/or mass transfer. As many manufacturing and mechanical processes depend upon efficient convective heat and/or mass transfer, the bound vortex concept features potential for terrestrial applications. The use of bound vortex impingement is shown to provide intense, localized, and well controlled heat and mass transfer enhancement. The work presented investigates the influence of bound vortex flow on the mass transfer from an impinged surface over a range of flow conditions. Naphthalene sublimations techniques are employed to capture local mass transfer distributions. Experimental flow conditions are recreated computationally and the heat transfer results. Peak and average surface heat transfer values are used to determine possible mass and heat transfer enhancement. It is concluded that the addition of bound vortex flow significantly increases mass and heat transfer enhancement from an impinged surface while maintaining advantageous compact flow characteristics.