<p> A continuous bubble reactor was used to study the transfer of oxygen into solutions of acetaldehyde. The reaction was catalysed by cobaltous acetate. The parameters investigated included temperature, catalyst concentration, air flow rate and column height.</p> <p> A mathematical model based on Houghton's work (36) was used to describe the absorption rate in the bubble column. The equation derived was solved numerically. The Sherwood numbers predicted by the theory were compared with those obtained experimentally.</p> / Thesis / Master of Engineering (MEngr)

In this study a modern hydrocode, blastFoam, that was designed for multi-phase compressible flow problems with applications suited for high-explosive detonation was investigated for underwater explosion (UNDEX) events. The problem of over-prediction for long-term UNDEX bubble behavior in modern hydrocodes that is known to be due to neglected secondary energy-loss mechanisms is evaluated. A single secondary energy-loss mechanism is established as the most significant loss mechanism that is being disregarded in current hydrocodes. The leading secondary energy-loss mechanism is formulated into a computational model that modifies the Jones-Wilkins-Lee (JWL) equation of state (EOS). Explanation and guidance for implementing the model in an Finite Volume Method (FVM) Eulerian-based hydrocode is provided. Through this research this thesis aims to improve long-term UNDEX bubble behavior prediction. Which is apart of a larger effort to improve numerical and computational predictions of UNDEX-induced structural ship response. / M.S. / Predicting the bubble dynamics of an underwater explosion (UNDEX) event is of great importance for the survivability of America’s warships. Shock waves from high-energy explosives are destructive to anything and everything nearby. Therefore, the design and development of military machinery rely on the accurate predictions of computational simulations. Computational solvers must be able to simulate the initial propagating shock waves from an underwater explosion, as well as the smaller following shock waves from the oscillating UNDEX bubble. Current incompressible solvers neglect the important compressible effects needed to predict the behavior for the UNDEX bubble oscillation cycle. If America’s Navy cannot predict the long-term damaging effects that a warship may encounter from an UNDEX bubble, then America’s warships and crew could not survive at battle. This study considers the assumptions used to simplify current UNDEX computational solvers in order to investigate and organize a compressible long-term simulation model. This model improves the multi-pulse bubble dynamic predictions for an UNDEX event, and will in return help design a long-term battle-ready warship for America’s future warfare.

In the face of rapid urbanization, megacities have witnessed the rise of skyscrapers as central social hubs. However, the predominant design approach for these towering structures has primarily focused on practical considerations, often overlooking the spiritual well-being of individuals. This oversight has led to detrimental consequences such as mental health challenges, pervasive social isolation, and increased crime rates. While halting skyscraper construction is not a practical solution, a compelling need emerges for a fresh design approach. A paradigm shift in skyscraper design is proposed, drawing inspiration from the organic formation of neighborhoods. This approach advocates for creating vertical settings within skyscrapers, which aim to offer rejuvenating experiences through abundant social spaces. These vertical neighborhoods blend communal learning areas, recreational zones, relaxation spaces, and green areas that foster natural human connections. By strongly emphasizing enclosed and open public spaces and implementing programs encouraging interaction, the envisioned design seeks to nurture healthy relationships and facilitate genuine human connections, ultimately fostering a more cohesive and closely-knit society. / Master of Architecture / Skyscrapers, while iconic in urban areas, often overlook the spiritual needs of individuals, leading to negative consequences like mental health issues, social isolation, and increased crime rates. Instead of halting skyscraper construction, a transformative design approach is needed. Imagine a skyscraper that resembles a horizontal neighborhood with blocks, streets, and social spaces. Inspired by the natural formation of districts, this concept proposes vertical neighborhoods that offer abundant social spaces and a healing experience. The design integrates communal learning areas, recreational zones, relaxation spaces, and green areas, promoting natural human connections and addressing the prevalent isolation in megacities. This design aims to nurture healthy relationships and facilitate genuine human connections by emphasizing enclosed and open public spaces and programs that encourage interaction, ultimately fostering a more united and connected society. This innovative approach seeks to redefine the purpose of skyscrapers, transforming them into vibrant communities that prioritize people's well-being and spiritual fulfillment.

The current study is an experimental and analytical investigation of JIB within the nucleate and transition boiling regimes. This study focuses on studying JIB within the stagnation zone of a free water jet. An experimental setup has been designed and built at the Thermal Processing Laboratory (TPL) with the capability of carrying out boiling experiments at heat fluxes up to 12 MW/m2. The JIB curves have been obtained under steady-state conditions for a wide range of jet conditions, higher than those considered during previous JIB studies. The effect of jet velocity, up to 3.8 m/s, and degree of subcooling, up to 49 °C, on the JIB curve has been studied. The results showed that both jet velocity and degree of subcooling have a weak effect on the nucleate boiling regime and significantly affect the transition boiling regime. Bubble dynamics under the impinging jet within the nucleate boiling regime and the stability of the vapor layer within the transition boiling regime have been investigated. An analytical mechanistic model, based on force balance and thermal balance equations, has been developed to predict the bubble growth rate and the BDD. The developed model was validated using current experimental data. The model gave a relative deviation of 17.8 %. Results of the mechanistic model within the stagnation zone showed that, amongst the three heat transfer mechanisms that affect bubble growth (i.e., the microlayer evaporation, the heat from the superheated layer, the convection heat loss to subcooled liquid), the microlayer evaporation is the most significant contributor to the rate of bubble growth. The current work conducted within the transition boiling regime was focused on the determination of the total wall heat flux within the stagnation zone, both experimentally and analytically. Steady-state experiments have been carried out during which the vapor layer stability was examined. The vapor layer breakup frequency was measured using a fiber-optic probe. Experiments were conducted at a jet velocity of 1 m/s and degrees of subcooling between 11 and 49 ºC. / Thesis / Doctor of Philosophy (PhD)

In an effort to understand the behavior of the laminar separation bubbles on NACA 0012 and Liebeck LA2573a airfoils at different Reynolds numbers and angles of attack, the boundary layers on the solid airfoils were investigated by measuring the mean and fluctuating components of the velocity profiles over the upper surfaces of the airfoils. Surface pressure measurements were carried out to complete the mapping of the laminar separation bubble and to calculate the lift generated by the airfoils. The experiments were carried out at Reynolds numbers of 150,000 and 250,000. The locations of separation, transition and reattachment were determined as functions of angle of attack and Reynolds number for the two airfoils. The drag was estimated from wake pressure measurements and was based on the momentum deficit generated by the airfoil. The size and location of the laminar separation bubble did not show significant changes with Reynolds number and angle of attack for values of the angle of attack between 0 and 6 d grees. The baseline results of the size and location of the laminar separation bubble on the LA2573a airfoil were used to design a suction distribution. This suction distribution was designed based on Thwaites’ criterion of separation. The effects of applying suction on the size and location of the laminar separation bubble were investigated. The results showed that the suction distribution designed in this work was effective in controlling the size of the laminar separation bubble, maintaining an un-separated laminar boundary layer to the transition point, and controlling the location of transition. The effects of different suction rates and distributions on the drag were investigated. Drag reductions of 14-24% were achieved. A figure of merit was defined as drag reductions divided by the equivalent suction drag to assess the worthiness of the utilizing suction on low Reynolds number flows. The values of the figure of merit were around 4.0 which proved that the penalty of using suction was significantly less than the gain obtained in reducing the drag.

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