Doctor of Philosophy, The Ohio State University, 2016, Food Science and Technology

Modern consumers' desire for health and wellness has stimulated the development of innovative food processing technologies to preserve nutrients and quality attributes. High pressure homogenization (HPH) is a continuous high pressure process that disrupts particles in the fluids and results in products with reduced particle size and modified textural properties. The effects of HPH on retention of phytochemicals and quality attributes of two food models (vegetable juice and emulsion) were studied. Raw tomato juice was processed by HPH (246 MPa, 99°C, <1 s), high pressure processing (HPP) (600 MPa, 46°C, 5 min), and thermal processing (TP) (90°C, 90 s). The contents of lycopene and its isomers, phytoene and phytofluene in HPH, HPP and TP treated tomato juices did not significantly differ from that in unprocessed juice, while a significant reduction in ß-carotene content was observed after TP treatment. HPH resulted in a significant reduction in mean particle size as compared to control, HPP and TP treated tomato juices. Moreover, an increase in apparent viscosity, redness (a*) and yellowness (b*) was observed in HPH treated juice as compared to those in control and HPP treated tomato juices. A model vegetable juice (mixture of tomato, carrot, kale, spinach, beet, blackberry and apple) was processed by pilot-scale HPH (232 MPa, 93°C, <1 s), HPP (600 MPa, 45°C, 5 min) and TP (92°C, 16 s), respectively. A reduction in contents of carotenoids and chlorophylls was observed in all treated juices. HPH significantly reduced particle size of vegetable juice, while HPP and TP resulted in an increase in mean particle size due to the formation of aggregates. An increase in the apparent viscosity of vegetable juice was observed after HPH, while no significant changes in viscosity for HPP and TP treated juices was noticed. HPH induced an increase in color attributes (L*, a*, b*), while a reduction in L* and b* values was observed in HPP and TP treated juices. Whey-pr (open full item for complete abstract)

Committee: V.M. Balasubramaniam (Advisor); Dennis Heldman (Committee Member); Farnaz Maleky (Committee Member); John Litchfield (Committee Member) Subjects: Food Science

Doctor of Philosophy, University of Akron, 2007, Polymer Science

One of the biggest challenges in solid state physics today is understanding the nature of the glass transition. Dynamic studies are critical in solving some of the problems in the field. Until recently, investigations of dynamics in glass formers were mostly carried out as a function of temperature. However, with the advancements in experimental techniques and methods, the interest towards using pressure as an additional experimental variable increased. The advantages of pressure over temperature are two-fold: First, it only alters the density of the system, whereas temperature changes both the thermal energy and the density, and secondly, one can achieve significant density changes (~20%) with pressure, whereas temperature creates smaller density changes (~5%). These advantages let researchers make direct comparisons of the results with glass transition models (i.e. free volume ideas). The dynamics in the frequency range between 1 GHz and 5 THz (fast dynamics), are thought to have a crucial role. Crystals in this frequency range have a Debye-like density of vibrational states. Glasses, however, have two extra contributions when compared to crystalline structures: (i) an anharmonic relaxation-like contribution that appears as a quasielastic scattering (QES) and (ii) a harmonic vibrational contribution, which shows up as the boson peak (BP) in light and neutron scattering spectra. It has also been shown experimentally that fast dynamics in glasses are strongly correlated with the temperature dependence of structural relaxation.In this dissertation the influence of pressure on fast dynamics in polyisobutylene, polyisoprene and low molecular weight polystyrene is investigated using inelastic light, neutron and X-ray scattering techniques. The results are compared to the predictions of the existing models.The results for all polymers studied showed that the boson peak shifts more strongly than sound modes, suggesting that the variations cannot be fully described by the (open full item for complete abstract)

Committee: Alexei Sokolov (Advisor) Subjects:

Doctor of Philosophy, Case Western Reserve University, 2024, Geological Sciences

Little is understood about the chemical evolution of banded iron formations (BIFs) subducted into the mantle during the Precambrian era. In general, the mantle becomes more reducing with increasing depth, with much of the deep mantle thought to be below the iron-wustite (IW) buffer. At equilibrium, under shallower mantle conditions, the hematite and magnetite in subducted BIFs would reduce wustite. In more deeply subducted BIFs, where the oxygen fugacity buffer is below IW, the wustite would reduce to iron metal. A key question is how rapidly iron oxide reduction reactions proceed at mantle pressures and temperatures. Fast reaction rate would imply that large amounts of wustite and/or metal may have precipitated in the deep mantle. BIFs that reduced to wustite and resisted further reduction could exist in the form of ULVZs (ulta-low velocity zones), as suggested by Dobson and Brodholt (2005). BIFs that fully reduced to iron metal could have produced large volume iron diapirs which would have been capable of sinking into the core and providing an inner core nucleation substrate, as suggested by Huguet et al. (2018). The studies reported here seek to answer these questions by determining the high-pressure, high-temperature reduction rates of iron oxides under mantle conditions. Chapter one describes the various approaches used to recreate banded iron formation subduction at high-pressures and high temperatures. Experiments explore temperatures from 600-1200 oC and pressures from 1.5-15 GPa. Chapter two addresses the first step of BIF reduction—the reduction of hematite and magnetite to wustite in the upper mantle. Experiments explore 14 temperatures from 600-1400 oC and pressures between 2-14 GPa. Chapter three addresses the final step in BIF reduction—the reduction of wustite to iron metal in the lower mantle.

Committee: James Van Orman (Advisor); Steven Hauck II (Committee Member); Alp Sehirlioglu (Committee Member); Beverly Saylor (Committee Member); Nathan Jacobson (Committee Member) Subjects: Experiments; Geochemistry; Geological; Geology

Master of Science in Mechanical Engineering (MSME), Wright State University, 2024, Mechanical Engineering

In the constant search for more efficient engines, one approach to gain performance is to reduce the weight of the low pressure turbine (LPT) module. This module can account for up to 30% of the total engine weight [1], and a reduction in LPT weight results in clear gains to engine performance and a reduction in engine cost. High lift airfoils accomplish this weight reduction by each blade extracting a larger amount of work from the flow and thus requiring fewer blades to drive the compressor when compared to conventional blades. However, high lift LPT blades, quantified by a high Zweifel loading coefficient Zw>1.15, encounter increasing loss at low Reynolds numbers. Named Reynolds lapse, this effect is problematic if the engine must operate at high altitude cruise conditions such as the case with unmanned air vehicles. The two airfoils of this study, the L2FHW and the L3FHW, were designed to be front loaded and to demonstrate favorable low Reynolds number loss characteristics. Both airfoils were tested in the Transonic Turbine Cascade (TTC) at the Air Force Research Laboratory Building 18 Test Cell 21. The TTC is capable of high Mach number and low Reynolds number flow via independent control of each. Each airfoil was tested across a broad range of Mach numbers: exit Mach 0.78 down to 0.2 and exit Reynolds numbers from 23,000 to 201,000. Across each condition an exit total pressure traverse yielded the loss coefficient of the cascade at that condition. It was found that across all design exit Mach conditions, 0.78, both airfoils experience fully attached flow and nearly flat loss behavior. This strongly aligns with the design level predictions made. At conditions beyond expected operating conditions, the L2FHW displayed resistance to un-reattaching separations at all conditions down to exit Mach 0.2 Reynolds number 23,300. The L3FHW showed un-reattaching separations at only the most extreme condition tested, exit Mach 0.2 and Reynolds number 25,300. (open full item for complete abstract)

Committee: Mitch Wolff Ph.D. (Advisor); Andrew Lethander Ph.D. (Committee Member); John Clark Ph.D. (Committee Member) Subjects: Aerospace Engineering

Master of Science, University of Akron, 2022, Geology

Stresses in the upper crust are redistributed to the lower crust after earthquakes. Stresses released by seismic slip induce crystal-plastic deformation in the mid to lower crust, which is composed of foliated, heterogeneous feldspathic rocks that deform and transfer stress back to the upper crust. Current models for the strength of the crust are primarily based on flow laws determined from experimentally deformed homogeneous quartzites or other monophase rocks. However, heterogeneities such as foliation orientations and foliation intensities, which are known to cause anisotropy of rock strength under brittle conditions, may cause viscous anisotropy at high temperatures and pressures where crystal-plastic mechanisms are dominant. To investigate if heterogeneities like foliation orientation and foliation intensity cause viscous anisotropy, I deformed weakly foliated Westerly Granite and strongly foliated Gneiss Minuti in different orientations that maximize (foliation at 45 degrees to the compression direction) and minimize (foliation parallel and foliation perpendicular to the compression direction) the shear stresses on the dispersed, elongate biotite grains in the quartz-feldspar framework, which should be the weakest and strongest orientations, respectively. These rocks were chosen because they both have similar low biotite contents (7%) and compositions: Westerly Granite is composed of 22 vol% quartz, 26 vol% K-feldspar, 45 vol% albite, and 7 vol% biotite and Gneiss Minuti is composed of 29 vol% quartz, 10 vol% K-feldspar, 53 vol% plagioclase and 7 vol% biotite. Experiments were performed using a Griggs apparatus at a temperature (T) of 800°C, confining pressure (Pc) of 1.5 GPa, and strain rate of 1.6 x 10-6/s. Westerly Granite and Gneiss Minuti reached peak stresses of 920 (+/- 50 MPa) and 670 (+/- 75 MPa), respectively, and viscous anisotropy was minor with anisotropy coefficients of 1.1x and 1.2x, respectively. Westerly Granite contained microstructures like (open full item for complete abstract)

Committee: Caleb Holyoke (Advisor); Molly Witter-Shelleman (Committee Member); John Peck (Committee Member) Subjects: Geology

Master of Science in Mechanical Engineering (MSME), Wright State University, 2019, Mechanical Engineering

Current hypersonic vehicles tend to be incapable of producing onboard power with traditional generators due to their use of supersonic combusting ramjets (scramjets). Because of this, they seek additional energy sources for supporting advanced electronics or other auxiliary power-dependent devices while requiring elaborate thermal management systems to combat temperatures exceeding 700ºC. The incorporation of Solid Oxide Fuel Cell (SOFCs) stacks is an efficient solution, capable of generating large quantities of power through the use of natural fuel sources at high temperatures. Developments in this thesis include the design, construction, and support of a system operating at hypersonic-environment conditions with a usable micro-fuel cell. The capability of testing a stack of SOFCs at both elevated temperature and pressure conditions with various natural fuel sources has become a sought-after experiment by many energy production affiliates. Experimentation for this thesis focuses on the optimization of fluid and thermal inputs to work towards supporting successful testing of SOFCs in both single and stacked formations with variable input conditions. Evaluation of the system's operational parameters were defined and recommendations for continual enhancement of primary components are given. This research acts as a transition into future fuel-cell testing development by the Air Force Research Labs (AFRL) and all supporting parties. APPROVED FOR PUBLIC RELEASE, CASE NUMBER 88ABW-2019-3904.

Committee: Rory A. Roberts Ph.D. (Advisor); Mitch Wolff Ph.D. (Committee Member); Scott K. Thomas Ph.D. (Committee Member) Subjects: Aerospace Engineering; Engineering; Mechanical Engineering

PhD, University of Cincinnati, 2019, Engineering and Applied Science: Chemical Engineering

The water gas shift (WGS) reaction of syngas (mainly containing CO, CO2, and H2) and subsequent H2/CO2 separation are key operations for H2 production from fossil fuels, agricultural and forestry biomass, and municipal wastes with pre-combustion CO2 capture in thermal electric power production by the emerging integrated gasification-combined cycle (IGCC) power plants. Hydrogen permselective membrane reactors (MR) are capable of achieving near complete CO conversion (?CO) with simultaneous H2/CO2 separation that can substantially simplify and intensify the process to lower the overall operation cost. However, up to date, there is a lack of WGS MRs, which are practically viable either due to membrane instability in the WGS reaction of real syngas or insufficient ?CO and H2 recovery (RH2). This dissertation reports the development and scale up of thermally and chemically stable tubular zeolite membranes for future industrial high temperature and high pressure WGS MR to achieve nearly complete ?CO when nearly total RH2 is achieved in the permeate stream. An effective in-situ crystallization method has been established for synthesizing MFI-type zeolite membranes on industrially meaningful low-cost commercial porous a-alumina tube supports. The zeolite membranes with a length of 35 cm exhibited a H2/CO2 selectivity (aH2/CO2) ranging from 10 to 45 and hydrogen permeance (Pm,H2), of 1 – 2*10-7 mol/m2·Pa·s at 500oC. The WGS reaction in the single tube zeolite MR has been studied at high temperature (500oC) and high pressure (20bar) using nanocrystalline Fe-based catalysts under practically meaningful space velocities and steam-to-CO ratios. The zeolite membranes with moderate aH2/CO2 and Pm,H2, exceeded the equilibrium conversion at >500oC and achieved ?CO >99.9%. Realization of near-complete ?CO must rely on the prevention of excessive permeation of CO when the membrane has imperfect H2/CO selectivity. For the porous membranes with imperfect H2/CO permeation selecti (open full item for complete abstract)

Committee: Junhang Dong Ph.D. (Committee Chair); Joo-Youp Lee Ph.D. (Committee Member); Peter Panagiotis Smirniotis Ph.D. (Committee Member); Maobing Tu Ph.D. (Committee Member) Subjects: Chemical Engineering

Master of Science, The Ohio State University, 2011, Geological Sciences

The viscosity of water is a first-order constraint on the transport of material from a subducting plate to the mantle wedge. The viscosity of fluids that are released during the dehydration of hydrous minerals during subduction can vary by more than 9 orders of magnitude between the limits of pure liquid water and silicate melts. Accurate determination of low viscosities (<1 mPa·s) for liquids at simultaneous high pressures (>1 GPa) and high temperatures (>373 K) is hindered by the geometry and sample size of high-pressure devices. Here the viscosity of water at pressures representative of the deep crust and upper mantle through use of Brownian motion in the hydrothermal diamond anvil cell (HDAC) is reported. By tracking the Brownian motion of 2.8 and 3.1 micron polystyrene spheres suspended in H2O, the viscosity of the water at high pressure and high temperature can be determined in situ using Einstein's relation. Accuracies of 3-10% are achieved and measurements are extended to pressures relevant to fluid release from subducting slabs and temperatures up to 150% of the melting temperature. Unhampered by wall effects of previous methods, the results from this study are consistent with a homologous temperature dependence of water viscosity in which the viscosity is a function of the ratio of the temperature to the melting temperature at a given pressure. Based on the homologous temperature dependence of water, transport times for fluids released from subducted plates inferred from geochemical proxies are too short for transport via porous flow alone, and suggest transport through a combination of channel-flow and porous flow implying hydrofracturing at 50-150 km depth.

Committee: Wendy Panero (Advisor); Michael Barton (Committee Member); David Cole (Committee Member) Subjects: Geophysics

Master of Science (MS), Ohio University, 2005, Chemical Engineering (Engineering)

The present study has been conducted to find the corrosion mechanisms and rates of an AISI 1018 steel in the presence of CO 2 and trace amounts of H 2 S using classical electrochemical techniques. The results obtained from experiments using electrochemical impedance spectroscopy measurements were theoretically analyzed by a semi-mechanistic model to reveal the conditions on the surface of the specimen used in the experiment. The experiments were designed to see the effect of different saturation values of iron carbonate and iron sulfide in the bulk solution on the corrosion rate of the sample. The experiments were conducted in a large scale (1000 lit) hastelloy flow loop at a fixed temperature of 60°C and total pressure of 7.9 bar. All experimental conditions were monitored regularly for the duration of the experiment. It was observed that the presence of trace amounts of H 2 S in the system decreased the corrosion rate significantly over time under the specific experimental conditions studied. This was due to the formation of an iron carbonate scale or iron sulfide scale, or both, which acted as a barrier to the diffusion of the corrosive species to the surface of the metal, thus decreasing corrosion rate.

Committee: Srdjan Nesic (Advisor) Subjects:

Master of Sciences, Case Western Reserve University, 2010, EMC - Mechanical Engineering

Acetone tracer-LIF in the gas phase is a widely used laser diagnostic technique in low to intermediate temperature and pressure combustion systems. In this work, we design, characterize, and validate a flexible static and flow system to study the independent and coupled effect of elevated pressure and temperature on the photophysics of acetone more relevant to practical engine like conditions (0.5 atm< P <40atm, 295K< T <700K) for an excitation wavelength of 282nm in nitrogen and air. It is shown that relative fluorescence increases for all pressures at elevated temperatures up to a maximum isotherm of ~425K; for subsequently higher temperatures, acetone fluorescence decreases. Acetone fluorescence is only moderately quenched in the presence of oxygen. The current work offers insight into the competing vibrational energy decay rates at elevated temperature and pressure and proposes a global re-optimization of model parameters from the original photophysical model developed by Thurber (1999).

Committee: Chih-Jen Sung PhD (Committee Chair); Yasuhiro Kamotani PhD (Committee Member); Gaurav Mittal PhD (Committee Member) Subjects: Aerospace Materials; Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 1967, Graduate School

Committee: Not Provided (Other) Subjects:

MS, University of Cincinnati, 2024, Engineering and Applied Science: Aerospace Engineering

This study underlines the impact of the flow structures on the internal flow field through shape-transitioning ducts with global favorable pressure gradients and local adverse pressure gradients, local to the shape-transitioning geometries. Results are evaluated for convergence apropos of acquisition frequency. This thesis presents preliminary results of flow structure measurement by introducing the structures with a cylindrical bluff body in the cross flow. Structure transport through the two duct configurations studied includes the free jet of a convergent nozzle and through a shape-transitioning nozzle. Particle Image Velocimetry (PIV) was employed in data acquisition considering its substantial spatiotemporal resolution necessary. Findings show that the free jet results are characterized by high-velocity jets, detached velocity deficit region at the tailing edge of the cylinder, and strong velocity gradients due to the shear layers formed between the wake, the jets, and the ambient. On the contrary, flow through the shape transitioning or favorable pressure gradient (FPG) nozzle reflects a well-behaved flow with a low-velocity region attached to the cylinder in most cases. The outcome difference primarily stems from the velocity experienced at the cylinder in each case. An examination of convergence, considering the acquiring frequency of the flow field data, unveiled a weighty impact of acquisition frequency on the results of turbulent flow fields. The ensemble average of the results based on the mathematical computation using analytical methods in the time domain revealed an overall comparable trend in results with notable distinctions in the near wake region. Convergence dependence of results on flow essence emerged with a comparison of the running averages at a point within and outside the wake. In conclusion, it was established that a smaller subset of image pairs drawn from a universal set is ample for effectively capturing the physics of the flow (open full item for complete abstract)

Committee: Daniel Cuppoletti Ph.D. (Committee Chair); Shaaban Abdallah Ph.D. (Committee Member); Paul Orkwis Ph.D. (Committee Member) Subjects: Aerospace Materials

DNP, Walsh University, 2024, Nursing

Hypertension (HTN) is one of the most diagnosed conditions and is increasing in prevalence at an extreme rate. Although evidence-based recommendations include self-measured blood pressure (SMBP) twice daily, many older adults do not monitor their blood pressure outside of the clinic setting. Consistent education from healthcare professionals to patients on how to correctly measure blood pressure and address other risk factors of hypertension is lacking. This research study was designed to implement and evaluate the effectiveness of an SMBP training program for registered nurses (RNs) providing case management support to community-based older adults with essential hypertension in a Managed Care Organization (MCO) across Wisconsin. RN case managers completed a learning module and their hypertension management knowledge was measured at three points, pre-intervention, immediately post-intervention, and one-month post-intervention. Results were then compared via RM-ANOVA. A retrospective review of patient charts was also completed to determine if there was an increase in the patient recorded frequency of SMBP following the RN case manager training and compared via independent t-tests. The RN case managers' hypertension management knowledge increased significantly following education, with a slight decrease in scores over time. Retrospective chart reviews revealed that the frequency of documented patient blood pressure self-measurements increased significantly following RN case manager education. Implementing an evidence-based SMBP training program for RN case managers is a successful intervention to support the management of essential hypertension in community-based older adults.

Committee: Shelly Amato-Curran (Advisor); Cheryl Bradas (Advisor) Subjects: Health Care Management; Health Education; Nursing

Doctor of Philosophy, University of Akron, 2024, Polymer Engineering

Reciprocating compressors are critical components for the natural gas energy infrastructure throughout the world. Proper lubrication of PTFE and PEEK based packings and piston rings (seals) in the compressor cylinder is necessary to prevent leaks of methane to the environment and allow efficient, reliable, and extended operation of the compressor. Cylinder lubrication is poorly understood and commonly cited as the reason for premature seal failures while being a major annual expense for compressor station operators. An industry priority is to reduce the amount of lubricant injected into the compressor cylinder. The lubricant is carried away by the process gas and collects in pipelines or other downstream equipment. To better understand the tribological aspects and physical phenomena of compressor cylinder lubrication, the effect of high pressure methane on the surface tension of common lubricants and sealing materials was investigated. Methane gas pressure exhibited an inverse relationship with liquid lubricant surface tension through a pendant drop test. Methane pressure also increased the contact angles of sessile drops of lubricants on the solid surfaces. Nitrogen pressure exhibited the same trends but to a lesser extent than methane. Analysis using the Owens, Wendt, Rabel and Kaelble calculation method revealed that as methane pressure increased, the surface free energy of the seal materials decreased. These results further revealed that increased gas pressure decreased the wettability of lubricants on the materials. PTFE based materials decreased much more than PEEK based materials. Spontaneous adsorption of the pressurized gases on the surface of the lubricant drops and sealing materials was determined to be the underlying cause of the reductions of surface energy. This new understanding is significant because it better explains the observed lubrication phenomena and may be able to guide the industry toward optimized lubrication, more efficient se (open full item for complete abstract)

Committee: Kevin Cavicchi (Advisor); Weinan Xu (Committee Chair); Christopher DellaCorte (Committee Member); Fardin Tayebeh Khabaz (Committee Member); Sadhan Jana (Committee Member) Subjects: Energy; Engineering; Materials Science; Mechanical Engineering

Master of Science in Mechanical Engineering, Cleveland State University, 2023, Washkewicz College of Engineering

In structural design, the distribution of wind-induced pressure exerted on structures is crucial. The pressure distribution for a particular building is often determined by scale model tests in boundary layer wind tunnels (BLWTs). For all combinations of interesting building shapes and wind factors, experiments with BLWTs must be done. Resource or physical testing restrictions may limit the acquisition of needed data because this procedure might be time- and resource-intensive. Finding a trustworthy method to cyber-enhance data-collecting operations in BLWTs is therefore sought. This research analyzes how machine learning approaches may improve traditional BLWT modeling to increase the information obtained from tests while proportionally lowering the work needed to complete them. The more general question centers on how a machine learning-enhanced method ultimately leads to approaches that learn as data are collected and subsequently optimize the execution of experiments to shorten the time needed to complete user-specified objectives. 3 Different Machine Learning models, namely, Support vector regressors, Gradient Boosting regressors, and Feed Forward Neural networks were used to predict the surface Averaged Mean pressure coefficients cp on Isolated high-rise buildings. The models were trained to predict average cp for missing angles and also used to train for varying dimensions. Both global and local approaches to training the models were used and compared. The Tokyo Polytechnic University's Aerodynamic Database for Isolated High-rise buildings was used to train all the models in this study. Local and global prediction approaches were used for the DNN and GBRT models and no considerable difference has been found between them. The DNN model showed the best accuracy with (R2 > 99%, MSE < 1.5%) among the used models for both missing angles and missing dimensions, and the other two models also showed high accuracy with (R2 > 97%, MSE < 4%).

Committee: Navid Goudarzi (Committee Chair); Prabaha Sikder (Committee Member); Mustafa Usta (Committee Member) Subjects: Artificial Intelligence; Design; Engineering; Urban Planning

Doctor of Philosophy, The Ohio State University, 2023, Aero/Astro Engineering

The feasibility of an active flow control enabled variable area turbine was explored. Pressurized air was ejected from the nozzle guide vanes to reduce the effective choke area, and mass flow rate through, the turbine inlet. A set of experimental and computational studies were conducted with varying actuator types and parameters to determine their effectiveness and develop models of the flow physics. Preliminary results from a simple quasi-1D converging-diverging nozzle, with an injection flow slot upstream of the throat, showed a 2.2:1 ratio between throttled mass flow rate and injected mass flow rate at a constant nozzle pressure ratio. The penetration of the injection flow and corresponding reduction in the primary flow streamtube were successfully visualized using a shadowgraph technique. Building on this success, a representative single passage nozzle guide vane transonic flowpath was constructed to demonstrate feasibility beyond the quasi-1D converging-diverging nozzle. Both secondary slot blowing from the vane pressure surface and vane suction surface just upstream of the passage throat again successfully reduced primary flow. In addition, fluidic vortex generators were used on the adjacent suction surface to reduce total pressure loss along the midspan and further throttle the primary flow. Computational fluid dynamics simulations were used to explore the effects of a variety of parameters on the flow blockage and actuator effectiveness. Simplified models were developed to describe the relationships of various factors impacting flow blockage, turning angle, and total pressure loss. Finally, the active flow control systems were simulated at engine relevant pressures and temperatures and found to have only a minimal drop in total pressure recovery and effectiveness, which could be predicted by the simplified blockage model.

Committee: Jeffrey Bons (Advisor); Datta Gaitonde (Committee Member); Randall Mathison (Committee Member) Subjects: Aerospace Engineering

Master of Science, The Ohio State University, 2023, Mechanical Engineering

In this research study, fuel sloshing for automotive applications isexperimentally observed inside a rectangular acrylic tank. A customized experimental setup includes a fuel tank that is designed (using CAD software) and manufactured using various machining techniques for each of the individual components. The experiment uses a high speed hydraulic actuator (2200 lbf capacity) to slosh a tank of volume 17.5 gallons up to a maximum speed of 2 mph. A triangular mechanical linkage is used to connect the actuator to the fuel tank and provide displacement and velocity amplification factor of 3:1. Experimental components and fixtures are designed such that various test conditions can be observed. This includes the tank inclination angle, and number and positions of baffles within the tank. In addition the percentage fill of the tank, and tank velocity are several parameters that are varied to investigate the change in fuel slosh. The pressure exerted by the fluid on the walls of the tank is measured by with the help of pressure transducers (0-5psig) at 10 distinct locations on the tank. The variation of pressure with time is observed by connecting pressure transducers to a National Instruments PXI Express data acquisition device and visualized using LabVIEW. Furthermore, the free surface of the fluid (water) is recorded using the Photron SA1 high-speed camera. The fluid (dyed dark blue to increase contrast) is tracked from raw high speed camera images using a customized image processing algorithm in MATLAB that captures fluid regions based on gray scale values and tolerances. The maximum pressure at specific time instants is noted and correlated with fluid slosh images amongst different cases in the test matrix. It is observed that wall pressure increases with an increase in % fill level and velocity. Furthermore, the number and position of baffles has no effect on impact pressure for some specific cases i.e., 90% fill and a velocity of 2 mph. As the fill level increa (open full item for complete abstract)

Committee: Jeremy Seidt (Advisor) Subjects: Design; Fluid Dynamics; Mechanical Engineering; Mechanics

Doctor of Philosophy (Ph.D.), University of Dayton, 2023, Aerospace Engineering

Turbomachinery components, such as the low pressure turbine, are highly complex rotating machines, therefore, conducting fundamental fluid mechanics studies in them is exceedingly difficult. For this reason, testing is generally completed in facilities such as linear cascades, like the one present in the Low Speed Wind Tunnel Facility at AFRL, which typically utilize a low freestream turbulence intensity, when in reality, the freestream turbulence intensity in a full, rotating low pressure turbine is likely much higher. Slightly elevating the freestream turbulence intensity (e.g., 3%) typically improves the Reynolds-lapse characteristics of a blade profile by affecting the transition process, reducing the detrimental effects of laminar boundary layer separation, and shifting the knee in the loss curve. Front loaded blades are more resistant to separation, however, they can experience high losses in the endwall region due to the complex vortical structures present. Therefore, a better understanding whether high levels of freestream turbulence intensity will increase the overall losses generated in the passage is important. An intial study with a jet based active grid was completed on the L2F blade. Based of the insight gained from that study, a new mechanical agitator based active grid was implemented into a linear cascade of L3FHW-LS blades in order to more effectively study how elevated FSTI impacts the endwall flow behavior and loss production. Coefficient of pressure measurements, three planes of SPIV, two additional planes of flow visualization, and three planes of total pressure loss measurements were collected. Impacts of incoming turbulence on the endwall losses as well as the endwall flow structures were assessed.

Committee: Markus Rumpfkeil (Advisor); Christopher Marks (Committee Member); Sidaard Gunasekaran (Committee Member); John Clark (Committee Member) Subjects: Aerospace Engineering

Doctor of Philosophy (PhD), Wright State University, 2023, Engineering PhD

Icing, or the formation of ice from water via freezing or water vapor via desublimation, is a phenomenon that commonly occurs within air cycle-based refrigeration systems and requires thermal control that limits system performance. In aircraft applications icing frequently occurs in the heat exchangers and turbine(s) that are part of the air cycle machine, the refrigeration unit of the environmental control system. Traditionally, water vapor is removed from an air cycle machine via condensing in a heat exchanger and subsequent high-pressure water separation. This approach is not capable of removing all of the vapor present at low altitude conditions, corresponding to a high risk of icing. To mitigate icing under these conditions, a membrane dehumidifier is considered to separate the water vapor that remains after condensing and liquid water separation. Three distinct investigations are conducted as part of this work. The first is aimed at modeling approaches for desublimation frosting, or frost growth on sufficiently cold flat surfaces. This results in a novel, analytical, and non-restrictive solution well-suited for representing frost growth and densification in moist air heat exchangers. The second investigation concerns membrane dehumidification and module design. A custom component model is developed and verified under aircraft conditions, then the Pareto frontier of volumetrically efficient membrane modules is characterized via a multi-objective optimization study. The final investigation evaluates three two-wheel air cycle subsystem architectures with differing dehumidification approaches: (1) condenser-based, (2) membrane dehumidifier-based, and (3) combined. Steady-state simulations are run for each of these over a range of flow rates and altitudes. The results demonstrate that incorporating a membrane dehumidifier reduces the turbine inlet saturation temperature, which mitigates icing in the turbine and reduces the required bypass fl (open full item for complete abstract)

Committee: Mitch Wolff Ph.D. (Advisor); James Menart Ph.D. (Committee Member); Abdeel Roman Ph.D. (Committee Member); José Camberos Ph.D., P.E. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2023, Food Science and Technology

Ultra-shear technology (UST) presents a promising way to preserve stable protein liquid foods. This dissertation investigated the effect of pressure, shear, temperature, and their interactions during UST on quality attributes and microbial inactivation. First, the impact of UST process parameters on milk was evaluated by subjecting to UST at 400 MPa/35 and 65°C. Untreated, high-pressure processed (HPP; 400 MPa/40°C/0 and 3 min) and thermal treated (72°C/15 s) milk served as controls. HPP did not cause particle size reduction but increased the viscosity up to 3.08 mPa·s compared with 2.68 mPa·s for untreated milk. 35°C UST reduced the particle diameter from 3511.76 nm (raw milk) to 291.45 nm and prevented creaming. To compare microbial safety of UST and HPP, cell suspension of Lactobacillus brevis (1.6×1010 CFU/mL) and spore suspension of Bacillus cereus (3.2×108 CFU/mL) were subjected to UST at 400 MPa/40 and 70°C. Thermal (0.1 MPa-70°C-0/5min) and HPP (400 MPa-40 and 70°C-0/5min) experiments were performed. HPP at 400 MPa /70°C/0 min resulted in 8.4 and 2.3 log reductions of L. brevis and B. cereus, respectively. After 70°C UST, L. brevis and B. cereus reduced by 7.1 and 1.6 logs, respectively. Different valve geometries, viz., ultra-shear valve, needle valve, and tubular valve, were evaluated. Ultra-shear valve produced inactivation of 2.0 and 7.1 logs for L. brevis at 40 and 70°C respectively, which was higher than needle valve and tubular valve. The ability of UST to obtain homogenous plant-dairy protein blends with varying protein and fat levels was evaluated. Milk-pea dispersions of 3 protein ratios viz., milk:pea 1:0.5, 1:1, and 1:3 were prepared. UST was performed at 400 MPa/40 and 70°C. HPP at 400 MPa/25±2°C/0 min and thermal treatment at 72°C/15s were conducted. Pea-dairy dispersions with 3 fat levels - Raw milk+Pea, Skim milk+Pea, Cream+Pea protein were prepared and UST-treated at 400 MPa/70°C. Discovery HR3-hybrid rheometer was used to determine visc (open full item for complete abstract)

Committee: Dr. V.M. Balasubramaniam (Advisor); Dr. Christopher Simons (Committee Member); Dr. Osvaldo H. Campanella (Committee Member); Dr. Rafael Jimenez-Flores (Committee Member) Subjects: Food Science