+publisher:"Georgia Tech" +contributor:("Yoda, Minami")

Georgia Tech

1. Hageman, Mitchell D. Experimental investigation of the thermal performance of gas-cooled divertor plate concepts.

Degree: MS, Mechanical Engineering, 2010, Georgia Tech

► Magnetic confinement fusion has the potential to provide a nearly inexhaustible source of energy. Current fusion energy research projects involve conceptual "Tokamak" reactors, inside of… (more)

▼ Magnetic confinement fusion has the potential to provide a nearly inexhaustible source of energy. Current fusion energy research projects involve conceptual "Tokamak" reactors, inside of which contaminants are "diverted" along magnetic field lines onto collection surfaces called divertor plates. Approximately 15% of the reactor's thermal power is focused on the divertor plates, creating a need for an effective cooling mechanism. Current extrapolations suggest that divertor plates will need to withstand heat fluxes of more than 10 MW/m2. The cooling mechanism will need to use a coolant compatible with the blanket system; currently helium, and use a minimal fraction of the reactor's available pumping power; ie: will need to experience minimal pressure drops. A leading cooling concept is the Helium Cooled Flat Plate Divertor (HCFP). This thesis experimentally examines four variations of the HCFP. The objectives are to: 1. Experimentally determine the thermal performance of the HCFP with a hexagonal pin-fin array in the gap between the impinging jet and the cooled surface over a range of flow rates and incident heat fluxes; 2. Experimentally measure the pressure drop associated with the hexagonal pin-fin array over a range of flow conditions; 3. Determine and compare the thermal performance of and pressure drop associated with the HCFP for two different slot widths, 0.5 mm and 2 mm over a range of flow rates and incident heat fluxes; 4. Compare the performance of the HCFP with a hexagonal pin-fin array with that of the HCFP with a metal-foam insert and the original HCFP; 5. Provide an experimental data set which can be used to validate numerical models of the HCFP design and its variants. 6. Analytically determine the maximum heat flux which the HCFP can be expected to withstand at theoretical operating conditions in the original and pin-fin array configurations. Advisors/Committee Members: Abdel-Khalik, Said (Committee Member), Ghiassiaan, Seyed (Committee Member), Yoda, Minami (Committee Member).

Subjects/Keywords: Pin-Fin; Fusion; Divertor; Tokamaks; Fusion reactors; Heat Transmission

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Hageman, M. D. (2010). Experimental investigation of the thermal performance of gas-cooled divertor plate concepts. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/34698

Chicago Manual of Style (16^th Edition):

Hageman, Mitchell D. “Experimental investigation of the thermal performance of gas-cooled divertor plate concepts.” 2010. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/34698.

MLA Handbook (7^th Edition):

Hageman, Mitchell D. “Experimental investigation of the thermal performance of gas-cooled divertor plate concepts.” 2010. Web. 15 Jun 2019.

Vancouver:

Hageman MD. Experimental investigation of the thermal performance of gas-cooled divertor plate concepts. [Internet] [Masters thesis]. Georgia Tech; 2010. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/34698.

Council of Science Editors:

Hageman MD. Experimental investigation of the thermal performance of gas-cooled divertor plate concepts. [Masters Thesis]. Georgia Tech; 2010. Available from: http://hdl.handle.net/1853/34698

Georgia Tech

2. Marsh, Richard. Experimental analysis of oil based cavitation peening in air.

Degree: MS, Mechanical Engineering, 2011, Georgia Tech

URL: http://hdl.handle.net/1853/43602

► Oil Jet Cavitation Peening in Air (OPA) is capable of inducing compressive residual stress in standard aerospace materials. This paper demonstrates the process capabilities of… (more)

Subjects/Keywords: Cavitation jet peening; Hydraulic fluid; Acoustic emission; Surface roughness; Hardening; Residual stress; Shot peening; Water jet peening; Surface hardening; Cavitation erosion; Jets

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Marsh, R. (2011). Experimental analysis of oil based cavitation peening in air. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/43602

Chicago Manual of Style (16^th Edition):

Marsh, Richard. “Experimental analysis of oil based cavitation peening in air.” 2011. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/43602.

MLA Handbook (7^th Edition):

Marsh, Richard. “Experimental analysis of oil based cavitation peening in air.” 2011. Web. 15 Jun 2019.

Vancouver:

Marsh R. Experimental analysis of oil based cavitation peening in air. [Internet] [Masters thesis]. Georgia Tech; 2011. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/43602.

Council of Science Editors:

Marsh R. Experimental analysis of oil based cavitation peening in air. [Masters Thesis]. Georgia Tech; 2011. Available from: http://hdl.handle.net/1853/43602

3. Akdeniz, Sercan. Thermal-hydraulic performance evaluation and optimization of the T-tube divertor design using numerical simulations.

Degree: MS, Mechanical Engineering, 2017, Georgia Tech

URL: http://hdl.handle.net/1853/58721

► A key technology issue in magnetic fusion energy is plasma-materials interactions (PMI). Because our understanding of how materials change when exposed to burning plasmas over… (more)

▼ A key technology issue in magnetic fusion energy is plasma-materials interactions (PMI). Because our understanding of how materials change when exposed to burning plasmas over extended periods is limited, Oak Ridge National Laboratory (ORNL) has proposed a linear plasma simulator, the Material-Plasma Exposure eXperiment (MPEX), to test various fusion-relevant materials. Since this facility will expose various materials to conditions similar to those in a burning plasma (except for fusion-relevant neutrons) at steady state, effectively cooling the target plate which will be exposed to steady-state heat fluxes of several MW/m2 is a major challenge. The objective of this Master's thesis is to use numerical simulation to evaluate and improve the thermal-hydraulic performance of a helium-cooled divertor design adapted for cooling the target plate in a linear plasma simulator. The T-tube divertor design, originally developed by the Advanced Reactor Innovations and Evaluations Compact Stellarator Study (ARIES-CS), was used as the starting point for these simulations because it can withstand a uniform heat flux of 10 MW/m2 over an area of several cm2 when cooled by helium (He) at 10 MPa and 600 °C. The T-tube was adapted for cooling the proposed target plate design for the MPEX using He at 4 MPa and room temperature. Given the much lower coolant temperatures, the simulations considered a target plate consisting of a copper chromium zirconium (CuCrZr) alloy, vs. the tungsten alloy proposed for the original T-tube. The simulations considered two different He flow configurations; a number of modified geometries were evaluated in an attempt to improve the thermal-hydraulic performance of both configurations. The simulations also compared the performance of two different target plate materials, namely the original CuCrZr and a titanium zirconium molybdenum (TZM) alloy. Advisors/Committee Members: Abdel-Khalik, Said I. (advisor), Yoda, Minami (advisor), Youchison, Dennis L. (committee member).

Subjects/Keywords: Plasma-facing materials; CFD; TZM; CuCrZr; Linear plasma simulator; T-tube; Divertor; Impinging jets

…cost-effective solution. This thesis specifically builds upon previous work at Georgia Tech…

11 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Akdeniz, S. (2017). Thermal-hydraulic performance evaluation and optimization of the T-tube divertor design using numerical simulations. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58721

Chicago Manual of Style (16^th Edition):

Akdeniz, Sercan. “Thermal-hydraulic performance evaluation and optimization of the T-tube divertor design using numerical simulations.” 2017. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/58721.

MLA Handbook (7^th Edition):

Akdeniz, Sercan. “Thermal-hydraulic performance evaluation and optimization of the T-tube divertor design using numerical simulations.” 2017. Web. 15 Jun 2019.

Vancouver:

Akdeniz S. Thermal-hydraulic performance evaluation and optimization of the T-tube divertor design using numerical simulations. [Internet] [Masters thesis]. Georgia Tech; 2017. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/58721.

Council of Science Editors:

Akdeniz S. Thermal-hydraulic performance evaluation and optimization of the T-tube divertor design using numerical simulations. [Masters Thesis]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/58721

4. Charry León, Carlos Humberto. Numerical simulation of water-cooled sample holders for high-heat flux testing of low-level irradiated materials.

Degree: MS, Mechanical Engineering, 2014, Georgia Tech

URL: http://hdl.handle.net/1853/53100

► The promise of a vast source of energy to power the world and protect our planet using fusion technology has been the driving force for… (more)

▼ The promise of a vast source of energy to power the world and protect our planet using fusion technology has been the driving force for scientists and engineers around the globe for more than sixty years. Although the materialization of this ideal still in the distance, multiple scientific and technological advances have been accomplished, which have brought commercial fusion power closer to a reality than it has ever been. As part of the collaborative effort in the pursuit of realizable fusion energy, the International Thermonuclear Experimental Reactor (ITER) is being developed by a coalition of nations of which the United States is a part of. One critical technological challenge for ITER is the development of adequate plasma facing materials (PFMs) that can withstand the strenuous conditions of operation. To date, high heat flux (HHF) testing has been conducted mainly on non-irradiated specimens due to the difficulty of working with radioactive specimens, such as instrument contamination. In this thesis, the new Irradiated Material Target Station (IMTS) facility for fusion materials at Oak Ridge National Laboratory (ORNL), in which the HHFs are provided by water-wall plasma-arc lamps (PALs), is considered for neutron-irradiated specimens, especially tungsten. The facility is being used to test irradiated plasma-facing components materials for magnetic fusion reactors as part of the US-Japan plasma facing components evaluation by tritium plasma, heat and neutron irradiation experiments (PHENIX). In order to conduct HHF testing on the PFMs various sample holders designs were developed to accommodate radioactive specimens during HHF testing. As part of the effort to design sample holders that are compatible with the IMTS facility, numerical simulations were performed for different water-cooled sample holder designs with the commercial computational fluid dynamics (CFD) software package, ANSYS™ FLUENT®. The numerical models are validated against experimental temperature measurements obtained from the IMTS facility. These experimentally validated numerical models are used to assess the thermal performance of two sample holder designs and establish safe limits for HHF testing under various operating conditions. The limiting parameter for the current configuration was determined for each sample holder design. For the Gen 1 sample holder, the maximum temperature reached within the Copper rod limits the allowable incident heat flux to about 6 MW/m². In the case of the Gen 2 sample holder, the maximum temperature reached within the Molybdenum clamping disk limits the allowable incident heat flux to about 5 MW/m². In addition, the numerical model are used to parametrically investigate the effect of the operating pressure, mass flow rate, and incident heat flux on the local heat flux distributions and peak surface temperatures. Finally, a comparative analysis is conducted to evaluate the advantages and disadvantages associated with the main design modifications between the two sample holder models as to evaluate their… Advisors/Committee Members: Yoda, Minami (advisor), Abdel-Khalik, Said I. (advisor), Ghiaasiaan, S. Mostafa (committee member).

Subjects/Keywords: Plasma facing materials; Fusion energy; IMTS facility; Sample holders; Irradiated samples; Fusion technology; ITER

10 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Charry León, C. H. (2014). Numerical simulation of water-cooled sample holders for high-heat flux testing of low-level irradiated materials. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53100

Chicago Manual of Style (16^th Edition):

Charry León, Carlos Humberto. “Numerical simulation of water-cooled sample holders for high-heat flux testing of low-level irradiated materials.” 2014. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/53100.

MLA Handbook (7^th Edition):

Charry León, Carlos Humberto. “Numerical simulation of water-cooled sample holders for high-heat flux testing of low-level irradiated materials.” 2014. Web. 15 Jun 2019.

Vancouver:

Charry León CH. Numerical simulation of water-cooled sample holders for high-heat flux testing of low-level irradiated materials. [Internet] [Masters thesis]. Georgia Tech; 2014. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/53100.

Council of Science Editors:

Charry León CH. Numerical simulation of water-cooled sample holders for high-heat flux testing of low-level irradiated materials. [Masters Thesis]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/53100

5. Ghosh, Rajat. Designing oscillating cilia for regulating particle motion in microfluidic devices.

Degree: MS, Mechanical Engineering, 2010, Georgia Tech

URL: http://hdl.handle.net/1853/33861

► We design actuated cilia that can maneuver microscopic particles normal to a microfluidic channel wall and transport microscopic particles parallel to the channel wall. For… (more)

Subjects/Keywords: Particle; Regulating; Devices; Designing; Microfluidic; Microfluidic devices; Cilia and ciliary motion

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ghosh, R. (2010). Designing oscillating cilia for regulating particle motion in microfluidic devices. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/33861

Chicago Manual of Style (16^th Edition):

Ghosh, Rajat. “Designing oscillating cilia for regulating particle motion in microfluidic devices.” 2010. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/33861.

MLA Handbook (7^th Edition):

Ghosh, Rajat. “Designing oscillating cilia for regulating particle motion in microfluidic devices.” 2010. Web. 15 Jun 2019.

Vancouver:

Ghosh R. Designing oscillating cilia for regulating particle motion in microfluidic devices. [Internet] [Masters thesis]. Georgia Tech; 2010. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/33861.

Council of Science Editors:

Ghosh R. Designing oscillating cilia for regulating particle motion in microfluidic devices. [Masters Thesis]. Georgia Tech; 2010. Available from: http://hdl.handle.net/1853/33861

6. Kilimnik, Alexander. Cross stream migration of compliant capsules in microfluidic channels.

Degree: MS, Mechanical Engineering, 2012, Georgia Tech

URL: http://hdl.handle.net/1853/43669

► An understanding of the motion of soft capsules in microchannels is useful for a number applications. This knowledge can be used to develop devices to… (more)

Subjects/Keywords: Inertial lift; Particle sorting; Microchannel; Microfluidic devices; Microfluidics; Colloids; Multiphase flow; Lattice Boltzmann methods; Computational fluid dynamics

11 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Kilimnik, A. (2012). Cross stream migration of compliant capsules in microfluidic channels. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/43669

Chicago Manual of Style (16^th Edition):

Kilimnik, Alexander. “Cross stream migration of compliant capsules in microfluidic channels.” 2012. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/43669.

MLA Handbook (7^th Edition):

Kilimnik, Alexander. “Cross stream migration of compliant capsules in microfluidic channels.” 2012. Web. 15 Jun 2019.

Vancouver:

Kilimnik A. Cross stream migration of compliant capsules in microfluidic channels. [Internet] [Masters thesis]. Georgia Tech; 2012. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/43669.

Council of Science Editors:

Kilimnik A. Cross stream migration of compliant capsules in microfluidic channels. [Masters Thesis]. Georgia Tech; 2012. Available from: http://hdl.handle.net/1853/43669

7. Redmond, Matthew J. Thermal management of 3-D stacked chips using thermoelectric and microfluidic devices.

Degree: MS, Mechanical Engineering, 2013, Georgia Tech

URL: http://hdl.handle.net/1853/50240

► This thesis employs computational and experimental methods to explore hotspot cooling and high heat flux removal from a 3-D stacked chip using thermoelectric and microfluidic… (more)

▼ This thesis employs computational and experimental methods to explore hotspot cooling and high heat flux removal from a 3-D stacked chip using thermoelectric and microfluidic devices. Stacked chips are expected to improve microelectronics performance, but present severe thermal management challenges. The thesis provides an assessment of both thermoelectric and microfluidic technologies and provides guidance for their implementation in the 3-D stacked chips. A detailed 3-D thermal model of a stacked electronic package with two dies and four ultrathin integrated TECs is developed to investigate the efficacy of TECs in hotspot cooling for 3-D technology. The numerical analysis suggests that TECs can be used for on demand cooling of hotspots in 3-D stacked chip architecture. A strong vertical coupling is observed between the top and bottom TECs and it is found that the bottom TECs can detrimentally heat the top hotspots. As a result, TECs need to be carefully placed inside the package to avoid such undesired heating. Thermal contact resistances between dies, inside the TEC module, and between the TEC and heat spreader are shown to significantly affect TEC performance. TECs are most effective for cooling localized hotspots, but microchannels are advantageous for cooling large background heat fluxes. In the present work, the results of heat transfer and pressure drop experiments in the microchannels with water as the working fluid are presented and compared to the previous microchannel experiments and CFD simulations. Heat removal rates of greater than 100 W/cm2 are demonstrated with these microchannels, with a pressure drop of 75 kPa or less. A novel empirical correlation modeling method is proposed, which uses finite element modeling to model conduction in the channel walls and substrate, coupled with an empirical correlation to determine the convection coefficient. This empirical correlation modeling method is compared to resistor network and CFD modeling. The proposed modeling method produced more accurate results than resistor network modeling, while solving 60% faster than a conjugate heat transfer model using CFD. The results of this work demonstrate that microchannels have the ability to remove high heat fluxes from microelectronic packages using water as a working fluid. Additionally, TECs can locally cool hotspots, but must be carefully placed to avoid undesired heating. Future work should focus on overcoming practical challenges including fabrication, cost, and reliability which are preventing these technologies from being fully leveraged. Advisors/Committee Members: Kumar, Satish (advisor), Joshi, Yogendra (committee member), Yoda, Minami (committee member).

Subjects/Keywords: Microelectronics cooling; Thermoelectric coolers; Microchannels; 3DICs; Stacked chips; Microelectronics; Three-dimensional integrated circuits; Heat Transmission

10 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Redmond, M. J. (2013). Thermal management of 3-D stacked chips using thermoelectric and microfluidic devices. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/50240

Chicago Manual of Style (16^th Edition):

Redmond, Matthew J. “Thermal management of 3-D stacked chips using thermoelectric and microfluidic devices.” 2013. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/50240.

MLA Handbook (7^th Edition):

Redmond, Matthew J. “Thermal management of 3-D stacked chips using thermoelectric and microfluidic devices.” 2013. Web. 15 Jun 2019.

Vancouver:

Redmond MJ. Thermal management of 3-D stacked chips using thermoelectric and microfluidic devices. [Internet] [Masters thesis]. Georgia Tech; 2013. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/50240.

Council of Science Editors:

Redmond MJ. Thermal management of 3-D stacked chips using thermoelectric and microfluidic devices. [Masters Thesis]. Georgia Tech; 2013. Available from: http://hdl.handle.net/1853/50240

8. Blackburn, Travis Lee. Electro-kinetically enhanced nano-metric material removal.

Degree: MS, Mechanical Engineering, 2008, Georgia Tech

URL: http://hdl.handle.net/1853/26600

► This project is a fundamental proof of concept to look at the feasibility of using field activated abrasive particles to achieve material removal on a… (more)

Subjects/Keywords: Ultra-precision metallic material removal; Chemical mechanical planarization; Miniature electronic equipment; Electrochemical cutting; Grinding and polishing; Semiconductors

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Blackburn, T. L. (2008). Electro-kinetically enhanced nano-metric material removal. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/26600

Chicago Manual of Style (16^th Edition):

Blackburn, Travis Lee. “Electro-kinetically enhanced nano-metric material removal.” 2008. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/26600.

MLA Handbook (7^th Edition):

Blackburn, Travis Lee. “Electro-kinetically enhanced nano-metric material removal.” 2008. Web. 15 Jun 2019.

Vancouver:

Blackburn TL. Electro-kinetically enhanced nano-metric material removal. [Internet] [Masters thesis]. Georgia Tech; 2008. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/26600.

Council of Science Editors:

Blackburn TL. Electro-kinetically enhanced nano-metric material removal. [Masters Thesis]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/26600

9. Yu, Su. Manufacturing analysis and design optimization of irrigation pumps for Bangladesh.

Degree: MS, Mechanical Engineering, 2017, Georgia Tech

URL: http://hdl.handle.net/1853/58163

► Irrigation pumps are indispensable to the production of major crops in Southeast Asia, especially in Bangladesh where agriculture plays a dominant role in the economy.… (more)

▼ Irrigation pumps are indispensable to the production of major crops in Southeast Asia, especially in Bangladesh where agriculture plays a dominant role in the economy. This thesis first analyzes the manufacturing and performance of prototype irrigation pumps, which are manufactured in Bangladesh using a Thai mixed-flow pump model. Then this thesis optimizes the design of the current model in a cost-effective and energy-efficient manner. This study is based upon several fundamental tenets of fluid mechanics. It begins with the definition of specific speed, which is critical to the pump selection among axial-flow, mixed flow, and centrifugal pumps. The study also discusses friction losses and the Affinity Law concepts, which are incorporated in the analysis of major and minor losses and of scaling at different RPMs. This study proceeds through multiple stages, including design of experiments, full-scale sample testing, prototype testing, computational fluid dynamics (CFD) simulation in SolidWorks Flow Simulation and ANSYS CFX, and results analysis. The research also involves several advanced techniques such as rapid prototyping, reverse engineering, computer-aided design (CAD), CFD, and analysis of variance (ANOVA) during these stages. During this study, the results of prototype and CFD simulation demonstrate good agreement with full-scale testing. From this study, several significant outcomes are generated and presented. The six manufactured samples exhibit geometric differences with an average standard deviation (STD) of 3.6%. These differences have only a small effect on pump performance, with STDs in shut-off head at all RPMs of less than 3.0% in prototype testing, 4.4% in SolidWorks simulation, and 5.6% in CFX simulation. The study implements the friction loss model to the pump system. For full-scale testing rigs, the loss coefficient is found to be 21.75 with a STD of 1.74. For prototype testing rigs, the loss coefficient is found to be 14.2 with a STD of 3.19. The thesis also implements Affinity Law scaling at different RPMs. This is supported by curve fits of the data with R-squared values of greater than 0.9 for flow rate and 0.99 for shut-off head. After that, a method of pump selection is presented for customers to find the most energy efficient pump and its operating condition. Finally, a design optimization of the four major design parameters, along with the significance level of each, is suggested for the current design of Thai mixed flow pump. Advisors/Committee Members: Colton, Jonathan S. (advisor), Alexeev, Alexander (committee member), Yoda, Minami (committee member).

Subjects/Keywords: Irrigation pump; Optimization; Numerical method; Developing countries; Simulation

…Affinity Law is discussed to relate the small-scale prototype test results from Georgia Tech to…

11 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Yu, S. (2017). Manufacturing analysis and design optimization of irrigation pumps for Bangladesh. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58163

Chicago Manual of Style (16^th Edition):

Yu, Su. “Manufacturing analysis and design optimization of irrigation pumps for Bangladesh.” 2017. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/58163.

MLA Handbook (7^th Edition):

Yu, Su. “Manufacturing analysis and design optimization of irrigation pumps for Bangladesh.” 2017. Web. 15 Jun 2019.

Vancouver:

Yu S. Manufacturing analysis and design optimization of irrigation pumps for Bangladesh. [Internet] [Masters thesis]. Georgia Tech; 2017. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/58163.

Council of Science Editors:

Yu S. Manufacturing analysis and design optimization of irrigation pumps for Bangladesh. [Masters Thesis]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/58163

Georgia Tech

10. Qin, Tongran. Buoyancy-thermocapillary convection of volatile fluids in confined and sealed geometries.

Degree: PhD, Mechanical Engineering, 2016, Georgia Tech

URL: http://hdl.handle.net/1853/54939

► Convection in a layer of fluid with a free surface due to a combination of thermocapillary stresses and buoyancy is a classic problem of fluid… (more)

▼ Convection in a layer of fluid with a free surface due to a combination of thermocapillary stresses and buoyancy is a classic problem of fluid mechanics. It has attracted increasing attentions recently due to its relevance for two-phase cooling. Many of the modern thermal management technologies exploit the large latent heats associated with phase change at the interface of volatile liquids, allowing compact devices to handle very high heat fluxes. To enhance phase change, such cooling devices usually employ a sealed cavity from which almost all noncondensable gases, such as air, have been evacuated. Heating one end of the cavity, and cooling the other, establishes a horizontal temperature gradient that drives the flow of the coolant. Although such flows have been studied extensively at atmospheric conditions, our fundamental understanding of the heat and mass transport for volatile fluids at reduced pressures remains limited. A comprehensive and quantitative numerical model of two-phase buoyancy-thermocapillary convection of confined volatile fluids subject to a horizontal temperature gradient has been developed, implemented, and validated against experiments as a part of this thesis research. Unlike previous simplified models used in the field, this new model incorporates a complete description of the momentum, mass, and heat transport in both the liquid and the gas phase, as well as phase change across the entire liquid-gas interface. Numerical simulations were used to improve our fundamental understanding of the importance of various physical effects (buoyancy, thermocapillary stresses, wetting properties of the liquid, etc.) on confined two-phase flows. In particular, the effect of noncondensables (air) was investigated by varying their average concentration from that corresponding to ambient conditions to zero, in which case the gas phase becomes a pure vapor. It was found that the composition of the gas phase has a crucial impact on heat and mass transport as well as on the flow stability. A simplified theoretical description of the flow and its stability was developed and used to explain many features of the numerical solutions and experimental observations that were not well understood previously. In particular, an analytical solution for the base return flow in the liquid layer was extended to the gas phase, justifying the previous ad-hoc assumption of the linear interfacial temperature profile. Linear stability analysis of this two-layer solution was also performed. It was found that as the concentration of noncondensables decreases, the instability responsible for the emergence of a convective pattern is delayed, which is mainly due to the enhancement of phase change. Finally, a simplified transport model was developed for heat pipes with wicks or microchannels that gives a closed-form analytical prediction for the heat transfer coefficient and the optimal size of the pores of the wick (or the width of the microchannels). Advisors/Committee Members: Grigoriev, Roman O. (advisor), Yoda, Minami (advisor), Neitzel, G. Paul (committee member), Smith, Marc K. (committee member), Schatz, Michael (committee member).

Subjects/Keywords: Buoyancy-thermocapillary convection; Buoyancy-Marangoni convection; Numerical simulation; Thermocapillarity; Flow stability; Free surface flow; Two-phase flow; Phase change; Phase change model; Kinetic theory of gases; Statistical rate theory; Nonequilibrium thermodynamics; Accommodation coefficient; Noncondensable gas

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Qin, T. (2016). Buoyancy-thermocapillary convection of volatile fluids in confined and sealed geometries. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/54939

Chicago Manual of Style (16^th Edition):

Qin, Tongran. “Buoyancy-thermocapillary convection of volatile fluids in confined and sealed geometries.” 2016. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/54939.

MLA Handbook (7^th Edition):

Qin, Tongran. “Buoyancy-thermocapillary convection of volatile fluids in confined and sealed geometries.” 2016. Web. 15 Jun 2019.

Vancouver:

Qin T. Buoyancy-thermocapillary convection of volatile fluids in confined and sealed geometries. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/54939.

Council of Science Editors:

Qin T. Buoyancy-thermocapillary convection of volatile fluids in confined and sealed geometries. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/54939

Georgia Tech

11. Mills, Brantley. On the use of dynamically similar experiments to evaluate the thermal performance of helium-cooled tungsten divertors.

Degree: PhD, Mechanical Engineering, 2014, Georgia Tech

URL: http://hdl.handle.net/1853/52292

► Many technological hurdles remain before a viable commercial magnetic fusion energy reactor can be constructed, including the development of plasma-facing components with long lifetimes that… (more)

▼ Many technological hurdles remain before a viable commercial magnetic fusion energy reactor can be constructed, including the development of plasma-facing components with long lifetimes that can survive the harsh environment inside a reactor. One such component, the divertor, which maintains the purity of the plasma by removing fusion byproducts from the reactor, must be able to accommodate very large incident heat fluxes of at least 10 MW/m² during normal operation. Modular helium-cooled tungsten divertors are one of the leading divertor designs for future commercial fusion reactors, and a number of different candidates have been proposed including the modular He-cooled divertor concept with pin array (HEMP), the modular He-cooled divertor concept with multiple-jet-cooling (HEMJ), and the helium-cooled flat plate (HCFP). These three designs typically operate with helium coolant inlet temperatures of 600 °C and inlet pressures of 10 MPa. Performing experiments at these conditions to evaluate the thermal performance of each design is both challenging and expensive. An alternative, more economical approach for evaluating different designs exploits dynamic similarity. Here, geometrically similar mockups of a single divertor module are tested using coolants at lower temperatures and pressures. Dynamically similar experiments were performed on an HEMP-like divertor with helium and argon at inlet temperatures close to room temperature, inlet pressures below 1.4 MPa, and incident heat fluxes up to 2 MW/m². The results are used to predict the maximum heat flux that the divertor can accommodate, and the pumping power as a fraction of incident thermal power, for a given maximum tungsten temperature. A new nondimensional parameter, the thermal conductivity ratio, is introduced in the Nusselt number correlations which accounts for variations in the amount of conduction heat transfer through the walls of the divertor module. Numerical simulations of the HCFP divertor are performed to investigate how the thermal conductivity ratio affects predictions for the maximum heat flux obtained in previous studies. Finally, a helium loop is constructed and used to perform dynamically similar experiments on an HEMJ module at inlet temperatures as high as 300 °C, inlet pressures of 10 MPa, and incident heat fluxes as great as 4.9 MW/m². The correlations generated from this work can be used in system codes to determine optimal designs and operating conditions for a variety of fusion reactor designs. Advisors/Committee Members: Yoda, Minami (advisor), Abdel-Khalik, Said I. (advisor), Hertel, Nolan E. (committee member), Grigoriev, Roman (committee member), Tillack, Mark (committee member).

Subjects/Keywords: Fusion; Divertor; Helium-cooled; Tungsten; Dynamic similarity; HEMJ; HEMP; HCFP

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Mills, B. (2014). On the use of dynamically similar experiments to evaluate the thermal performance of helium-cooled tungsten divertors. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/52292

Chicago Manual of Style (16^th Edition):

Mills, Brantley. “On the use of dynamically similar experiments to evaluate the thermal performance of helium-cooled tungsten divertors.” 2014. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/52292.

MLA Handbook (7^th Edition):

Mills, Brantley. “On the use of dynamically similar experiments to evaluate the thermal performance of helium-cooled tungsten divertors.” 2014. Web. 15 Jun 2019.

Vancouver:

Mills B. On the use of dynamically similar experiments to evaluate the thermal performance of helium-cooled tungsten divertors. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/52292.

Council of Science Editors:

Mills B. On the use of dynamically similar experiments to evaluate the thermal performance of helium-cooled tungsten divertors. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/52292

Georgia Tech

12. Peng, Zhengchun. Parallel manipulation of individual magnetic microbeads for lab-on-a-chip applications.

Degree: PhD, Mechanical Engineering, 2011, Georgia Tech

URL: http://hdl.handle.net/1853/39469

► Many scientists and engineers are turning to lab-on-a-chip systems for cheaper and high throughput analysis of chemical reactions and biomolecular interactions. In this work, we… (more)

▼ Many scientists and engineers are turning to lab-on-a-chip systems for cheaper and high throughput analysis of chemical reactions and biomolecular interactions. In this work, we developed several lab-on-a-chip modules based on novel manipulations of individual microbeads inside microchannels. The first manipulation method employs arrays of soft ferromagnetic patterns fabricated inside a microfluidic channel and subjected to an external rotating magnetic field. We demonstrated that the system can be used to assemble individual beads (1-3µm) from a flow of suspended beads into a regular array on the chip, hence improving the integrated electrochemical detection of biomolecules bound to the bead surface. In addition, the microbeads can follow the external magnet rotating at very high speeds and simultaneously orbit around individual soft magnets on the chip. We employed this manipulation mode for efficient sample mixing in continuous microflow. Furthermore, we discovered a simple but effective way of transporting the microbeads on-chip in the rotating field. Selective transport of microbeads with different size was also realized, providing a platform for effective sample separation on a chip. The second manipulation method integrates magnetic and dielectrophoretic manipulations of the same microbeads. The device combines tapered conducting wires and fingered electrodes to generate desirable magnetic and electric fields, respectively. By externally programming the magnetic attraction and dielectrophoretic repulsion forces, out-of-plane oscillation of the microbeads across the channel height was realized. Furthermore, we demonstrated the tweezing of microbeads in liquid with high spatial resolutions by fine-tuning the net force from magnetic attraction and dielectrophoretic repulsion of the beads. The high-resolution control of the out-of-plane motion of the microbeads has led to the invention of massively parallel biomolecular tweezers. Advisors/Committee Members: Hesketh, Peter (Committee Chair), Allen, Mark (Committee Member), Degertekin, Levent (Committee Member), Lu, Hang (Committee Member), Yoda, Minami (Committee Member).

Subjects/Keywords: Biomolecular tweezers; Magnetic transport; Microfluidic mixer; Dielectrophoresis; Microparticle-based immunoassay; Magnetophoresis; Superparamagnetic microbeads; Chemical reactions; Microfluidics; Dielectrics

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Peng, Z. (2011). Parallel manipulation of individual magnetic microbeads for lab-on-a-chip applications. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/39469

Chicago Manual of Style (16^th Edition):

Peng, Zhengchun. “Parallel manipulation of individual magnetic microbeads for lab-on-a-chip applications.” 2011. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/39469.

MLA Handbook (7^th Edition):

Peng, Zhengchun. “Parallel manipulation of individual magnetic microbeads for lab-on-a-chip applications.” 2011. Web. 15 Jun 2019.

Vancouver:

Peng Z. Parallel manipulation of individual magnetic microbeads for lab-on-a-chip applications. [Internet] [Doctoral dissertation]. Georgia Tech; 2011. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/39469.

Council of Science Editors:

Peng Z. Parallel manipulation of individual magnetic microbeads for lab-on-a-chip applications. [Doctoral Dissertation]. Georgia Tech; 2011. Available from: http://hdl.handle.net/1853/39469

Georgia Tech

13. Marcon, Andrea. Water cavitation peening for aerospace materials.

Degree: PhD, Mechanical Engineering, 2017, Georgia Tech

URL: http://hdl.handle.net/1853/59765

► Conventional shot peening has been used for almost a century as a means to mechanically improve the fatigue and corrosion resistance of metals. It employs… (more)

▼ Conventional shot peening has been used for almost a century as a means to mechanically improve the fatigue and corrosion resistance of metals. It employs spherical shots of different size and materials to introduce compressive residual stress in the surface layers of metals, thereby improving their mechanical integrity when subjected to cyclic loading and/or a corrosive environment. However, this technique is also characterized by substantial surface roughening, high consumables cost and workpiece contamination. Over the past few decades, a number of alternative peening techniques have been developed to overcome these limitations. Among them, water cavitation jet peening (WCP) has showed promising preliminary results in further extending fatigue life, reducing surface modification and lowering equipment and operating costs. Nevertheless, there is limited scientific understanding of this process at present. Consequently, there is a need for further studies aimed at developing detailed fundamental understanding of the cavitation jet peening process, exploring its potential and adequately characterizing the process to satisfy the demanding requirements set by industry, especially for aerospace applications. This thesis presents an investigation of a novel co-flow water cavitation jet peening (WCP) system that expands the limited understanding of the process and addresses the limitations of the currently available peening processes. The basic concept involves creating cavitation by injecting a high speed jet into a low speed jet in a concentric (or co-flow) configuration, and placing the co-flow nozzle at an optimum distance from the workpiece surface. By suitably controlling the flow parameters and nozzle dimensions, it is possible to produce a sufficiently aggressive cavitation cloud capable of plastically deforming metal surfaces and introducing beneficial compressive residual stresses. The main focus of this thesis is on the development of a WCP peening and the fundamental characterization of the cavitating flow for peening applications. The flow characterization is carried out by means of accelerated erosion tests and strip curvature tests. Accelerated erosion tests are commonly used in the field of cavitation erosion to evaluate cavitation intensity and rank the erosion resistance of common engineering materials. Strip curvature tests are an established practice in the peening field used to evaluate the effectiveness of peening treatments. The results indicate that cavitation intensity and peening capability can be substantially increased by adopting suitable flow conditions, and that the optimum outer flow velocity Vout and normalized standoff distance sN are essentially independent of the inner flow velocity Vin within the range adopted for this study. Peening tests carried out on Aluminum 7075-T651 give higher and deeper residual stresses compared to shot peening while lowering the surface roughening, potentially leading to a substantial increase in the fatigue life of components treated by WCP compared to… Advisors/Committee Members: Melkote, Shreyes (advisor), Yoda, Minami (committee member), Neu, Richard (committee member), Saldana, Christopher (committee member), Castle, James (committee member).

Subjects/Keywords: Peening; Cavitation; Fatigue

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Marcon, A. (2017). Water cavitation peening for aerospace materials. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59765

Chicago Manual of Style (16^th Edition):

Marcon, Andrea. “Water cavitation peening for aerospace materials.” 2017. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/59765.

MLA Handbook (7^th Edition):

Marcon, Andrea. “Water cavitation peening for aerospace materials.” 2017. Web. 15 Jun 2019.

Vancouver:

Marcon A. Water cavitation peening for aerospace materials. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/59765.

Council of Science Editors:

Marcon A. Water cavitation peening for aerospace materials. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/59765

14. Li, Yaofa. Experimental studies of Marangoni convection with buoyancy in simple and binary fluids.

Degree: PhD, Mechanical Engineering, 2015, Georgia Tech

URL: http://hdl.handle.net/1853/53893

► The flow in a layer of volatile fluid driven by a horizontal temperature gradient is a fundamental transport model for numerous evaporative passive cooling applications.… (more)

▼ The flow in a layer of volatile fluid driven by a horizontal temperature gradient is a fundamental transport model for numerous evaporative passive cooling applications. When a thin film of a volatile liquid is subject to a horizontal temperature gradient, changes in the surface tension at the free surface lead to Marangoni stresses that drive the flow. In a thicker liquid layer, the flow is also affected by buoyancy. This thesis describes experimental studies of convection driven by a combined action of Marangoni stresses and buoyancy in simple and binary volatile liquid layers confined in a sealed rectangular cavity heated at one end and cooled at the other. Experiments with varying concentrations of noncondensables (i.e., air) ca were performed to investigate their effect on the phase change and heat and mass transport. In the simple liquid, thermocapillary stresses drive the liquid near the free surface away from the heated end. Varying ca is shown to strongly affect the stability of this buoyancy-thermocapillary flow for Marangoni numbers Ma = 290 - 3600 and dynamic Bond numbers BoD = 0.56 - 0.82: removing air suppresses transition to multicellular and unsteady flow. The results are compared with numerical simulations and linear stability analysis. In the binary liquid considered here, a methanol-water (MeOH-H2O) mixture, solutocapillary stresses drive the flow near the free surface towards the heated end. Four distinct flow regimes are identified for this complex flow driven by thermocapillarity, solutocapillarity, and buoyancy, and are summarized in a flow regime map as a function of ca and the liquid composition (MeOH concentration). At low ca, solutocapillary effects are strong enough to drive the liquid near the free surface towards the heated end over the entire liquid layer, suggesting that binary-fluid coolants could significantly reduce film dryout. Advisors/Committee Members: Yoda, Minami (advisor), Joshi, Yogendra (committee member), Ghiaasiaan, S. Mostafa (committee member), Grigoriev, Roman (committee member), Schatz, Michael (committee member).

Subjects/Keywords: Marangoni convection; Surface tension; Thermocapillarity; Solutocapillarity; Buoyancy; Phase change; Noncondensables; Flow stability; Evaporative cooling; Particle image velocimetry; Flow visualization

15 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Li, Y. (2015). Experimental studies of Marangoni convection with buoyancy in simple and binary fluids. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53893

Chicago Manual of Style (16^th Edition):

Li, Yaofa. “Experimental studies of Marangoni convection with buoyancy in simple and binary fluids.” 2015. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/53893.

MLA Handbook (7^th Edition):

Li, Yaofa. “Experimental studies of Marangoni convection with buoyancy in simple and binary fluids.” 2015. Web. 15 Jun 2019.

Vancouver:

Li Y. Experimental studies of Marangoni convection with buoyancy in simple and binary fluids. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/53893.

Council of Science Editors:

Li Y. Experimental studies of Marangoni convection with buoyancy in simple and binary fluids. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53893

Georgia Tech

15. Cazan, Radu. Dynamics of swirling flows induced by twisted tapes in circular pipes.

Degree: PhD, Mechanical Engineering, 2010, Georgia Tech

URL: http://hdl.handle.net/1853/33944

► The present study describes the flow characteristics of swirling flows induced by twisted tape inserts in circular pipes. The study is focused on the secondary… (more)

Subjects/Keywords: Helical vortex; Swirling flow; Flow visualization; Twisted tape; Vortex dynamics; Rotating fluids; Eddies; Turbulence; Pipe Fluid dynamics; Vortex-motion

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Cazan, R. (2010). Dynamics of swirling flows induced by twisted tapes in circular pipes. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/33944

Chicago Manual of Style (16^th Edition):

Cazan, Radu. “Dynamics of swirling flows induced by twisted tapes in circular pipes.” 2010. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/33944.

MLA Handbook (7^th Edition):

Cazan, Radu. “Dynamics of swirling flows induced by twisted tapes in circular pipes.” 2010. Web. 15 Jun 2019.

Vancouver:

Cazan R. Dynamics of swirling flows induced by twisted tapes in circular pipes. [Internet] [Doctoral dissertation]. Georgia Tech; 2010. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/33944.

Council of Science Editors:

Cazan R. Dynamics of swirling flows induced by twisted tapes in circular pipes. [Doctoral Dissertation]. Georgia Tech; 2010. Available from: http://hdl.handle.net/1853/33944

Georgia Tech

16. Zhao, Bailey. Optimization of the thermal-hydraulic performance of the helium-cooled modular divertor with multiple jets.

Degree: PhD, Mechanical Engineering, 2017, Georgia Tech

URL: http://hdl.handle.net/1853/59249

► The divertor is a key plasma-facing component of future commercial magnetic fusion energy (MFE) reactors that helps sustain fusion reactions by removing helium ash particles… (more)

▼ The divertor is a key plasma-facing component of future commercial magnetic fusion energy (MFE) reactors that helps sustain fusion reactions by removing helium ash particles and impurities from the core plasma. The divertor target plates are therefore subject to high steady-state incident heat fluxes, expected to be at least 10 MW/m² in the international demonstration (DEMO) fusion reactor. The helium-cooled modular divertor with multiple jets (HEMJ), which uses 25 impinging jets of helium to cool plasma-facing tungsten tiles, is a leading candidate for DEMO. Experiments were performed on a single HEMJ module to characterize its thermal-hydraulic performance at coolant inlet temperatures up to 425 °C, inlet pressures of 10 MPa, and incident heat fluxes up to 6.6 MW/m² using a closed helium loop. The effect of the jets-to-impingement surface separation distance was experimentally investigated. A numerical model was developed with a commercial software package, and validated against experimental data. The model was used to evaluate the thermo-mechanical performance of the HEMJ, and to optimize the divertor geometry toward a design that is more favorable to fabricate. The optimized HEMJ variant was fabricated and tested in the helium loop. The experimental results were used to develop parametric design charts that predict the HEMJ thermal performance at prototypical inlet temperatures of 600 °C and heat fluxes of 10 MW/m². The simulation results provide estimates of thermally-induced stresses and expansion. The results suggest that the HEMJ can accommodate 10 MW/m² while keeping the pumping power requirements within specified limits. The simpler HEMJ variant can accommodate 8 MW/m² under the same conditions, which could simplify manufacturing and reduce fabrication costs for O(10⁶) modules. Advisors/Committee Members: Yoda, Minami (advisor), Abdel-Khalik, Said I. (advisor), Ghiaasiaan, Seyed M. (committee member), Joshi, Yogendra (committee member), Schatz, Michael (committee member), Katoh, Yutai (committee member).

Subjects/Keywords: Helium-cooled divertor; HEMJ; Jet impingement

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhao, B. (2017). Optimization of the thermal-hydraulic performance of the helium-cooled modular divertor with multiple jets. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59249

Chicago Manual of Style (16^th Edition):

Zhao, Bailey. “Optimization of the thermal-hydraulic performance of the helium-cooled modular divertor with multiple jets.” 2017. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/59249.

MLA Handbook (7^th Edition):

Zhao, Bailey. “Optimization of the thermal-hydraulic performance of the helium-cooled modular divertor with multiple jets.” 2017. Web. 15 Jun 2019.

Vancouver:

Zhao B. Optimization of the thermal-hydraulic performance of the helium-cooled modular divertor with multiple jets. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/59249.

Council of Science Editors:

Zhao B. Optimization of the thermal-hydraulic performance of the helium-cooled modular divertor with multiple jets. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/59249

17. Gopalakrishnan, Priya. Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor.

Degree: PhD, Aerospace Engineering, 2008, Georgia Tech

URL: http://hdl.handle.net/1853/22682

► The performance of dry, low NOx gas turbines, which employ lean premixed (or partially premixed) combustors, is often limited by combustor stability. To overcome this… (more)

▼ The performance of dry, low NOx gas turbines, which employ lean premixed (or partially premixed) combustors, is often limited by combustor stability. To overcome this issue, a novel design, referred to as a Stagnation Point Reverse Flow (SPRF) combustor, has been recently demonstrated. The SPRF combustor has been shown to produce low NOx emissions with both gaseous and liquid fuels. The objective of this thesis is to elucidate the interactions between the flowfield and combustion processes in this combustor for gas- and liquid-fueled operation. This is achieved with experimental measurements employing various optical diagnostic techniques. These include Particle Image Velocimetry (PIV), chemiluminescence imaging, Planar Laser-Induced Fluorescence (PLIF) of OH radicals and laser scattering from liquid droplets. Velocity measurements in gas-fueled operation show that both nonreacting and reacting flows exhibit a stagnation region with low mean velocity and high turbulence intensities. The high shear between the forward and reverse flows causes significant recirculation resulting in enhanced entrainment and mixing of the returning product gases into the incoming reactant jet for the reacting flow cases, which enables stable operation of the combustor at very lean equivalence ratios. Nonpremixed operation produces a flowfield similar to premixed case except in the near-field region where high turbulence intensities result in significant fuel-air mixing before combustion occurs. Operation of the SPRF combustor with liquid Jet-A is also investigated experimentally. The results indicate that while the overall flow features are similar to the gas-fueled SPRF combustor, the combustion characteristics and NOx performance in liquid operation are strongly controlled by fuel dispersion and evaporation. Injecting the liquid at the exit of the air annulus results in a highly lifted flame, similar to nonpremixed gaseous operation. On the other hand, retracting the fuel injector well inside the air annulus produces a well-dispersed fuel pattern at the reactant inlet leading to a reduction of the equivalence ratio in the fuel consuming reaction zones. Since the effective Dahmkohler number increases with global equivalence ratio, the difference in NOx emissions is more pronounced at higher fuel-air ratios as the retracted injector lowers the relative mixing time compared to the flush case. Advisors/Committee Members: Seitzman, Jerry (Committee Chair), Gaeta, Richard (Committee Member), Jagoda, Jeff (Committee Member), Neumeier, Yedidia (Committee Member), Yoda, Minami (Committee Member), Zinn, Ben (Committee Member).

Subjects/Keywords: Low NOx combustor; Flow-flame interactions; Stagnation; Fuel dispersion; Combustion; Waste gases; Waste minimization; Environmental engineering

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Gopalakrishnan, P. (2008). Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/22682

Chicago Manual of Style (16^th Edition):

Gopalakrishnan, Priya. “Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor.” 2008. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/22682.

MLA Handbook (7^th Edition):

Gopalakrishnan, Priya. “Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor.” 2008. Web. 15 Jun 2019.

Vancouver:

Gopalakrishnan P. Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor. [Internet] [Doctoral dissertation]. Georgia Tech; 2008. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/22682.

Council of Science Editors:

Gopalakrishnan P. Effects of the reacting flowfield on combustion processes in a stagnation point reverse flow combustor. [Doctoral Dissertation]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/22682

18. Woo, Tak Kwong. Transitory control of separated shear layer using impulsive jet actuation.

Degree: PhD, Mechanical Engineering, 2014, Georgia Tech

URL: http://hdl.handle.net/1853/52980

► The dynamics of controlled transitory 2- and 3-D attachment of the separated flow over a 2-D airfoil model are investigated in wind tunnel experiments. Pulsed… (more)

▼ The dynamics of controlled transitory 2- and 3-D attachment of the separated flow over a 2-D airfoil model are investigated in wind tunnel experiments. Pulsed actuation is effected on time scales that are an order of magnitude shorter than the characteristic convective time scale of the base flow by momentary jets that are generated by a spanwise array of combustion-based actuators. The effects of the transitory actuation on the aerodynamic characteristics of the airfoil are assessed using measurements of the global lift force and pitching moment and of streamwise distributions of surface pressure, and planar and stereoscopic particle image velocimetry (PIV) acquired phase-locked to the actuation waveform. A single spanwise-bounded actuation pulse leads to 2-D severing of the separated vorticity layer and the subsequent shedding of a large-scale stall vortex that are followed by momentary attachment of the upstream boundary layer and ultimately re-separation that are accompanied by a strong transitory change in the airfoil's circulation. It is shown that the primary mechanism for the attachment is alteration of the adverse pressure gradient of the separated base flow by local blockage of the momentary jet and.the formation of the large-scale stall vortex. The disparity between the characteristic time scales of flow attachment and subsequent separation [O(Tconv) and O(10Tconv), respectively] is exploited for temporal and spatial extensions of the attachment and enhancement of the global aerodynamic performance using strings of successive actuation pulses. Pulsed actuation effected by an unbounded actuator array leads to spanwise spreading of the induced transitory 3-D flow attachment well beyond the spanwise edges of the actuators. It is shown that 3-D pulsed actuation enhances the accumulation of vorticity over the airfoil and improves its aerodynamic performance compared to 2-D, spanwise-bounded actuation. When the airfoil is undergoing time-periodic pitch oscillations beyond its static stall margin, a sequence of staged 3-D actuation pulses coupled to the airfoil's motion can lead to reduced lift hysteresis and increased pitch stability (lower “negative damping”) that are typically associated with the presence of dynamic stall. Advisors/Committee Members: Glezer, Ari (advisor), Yoda, Minami (committee member), Costello, Mark (committee member), Smith, Marc K. (committee member), Smith, Marilyn J. (committee member).

Subjects/Keywords: Aerodynamics; Fluid mechanics; Flow control; Wind tunnel; Combustion actuators

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Woo, T. K. (2014). Transitory control of separated shear layer using impulsive jet actuation. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/52980

Chicago Manual of Style (16^th Edition):

Woo, Tak Kwong. “Transitory control of separated shear layer using impulsive jet actuation.” 2014. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/52980.

MLA Handbook (7^th Edition):

Woo, Tak Kwong. “Transitory control of separated shear layer using impulsive jet actuation.” 2014. Web. 15 Jun 2019.

Vancouver:

Woo TK. Transitory control of separated shear layer using impulsive jet actuation. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/52980.

Council of Science Editors:

Woo TK. Transitory control of separated shear layer using impulsive jet actuation. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/52980

19. Perkins, Adam Christopher. Mechanisms of instability in Rayleigh-Bénard convection.

Degree: PhD, Physics, 2011, Georgia Tech

URL: http://hdl.handle.net/1853/42768

► In many systems, instabilities can lead to time-dependent behavior, and instabilities can act as mechanisms for sustained chaos; an understanding of the dynamical modes governing… (more)

Subjects/Keywords: Rayleigh-Bénard convection; Instability; Dynamical mode; LETKF; State estimation; Pattern formation; Chaos; Rayleigh-Bénard convection; Chaotic behavior in systems

10 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Perkins, A. C. (2011). Mechanisms of instability in Rayleigh-Bénard convection. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/42768

Chicago Manual of Style (16^th Edition):

Perkins, Adam Christopher. “Mechanisms of instability in Rayleigh-Bénard convection.” 2011. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/42768.

MLA Handbook (7^th Edition):

Perkins, Adam Christopher. “Mechanisms of instability in Rayleigh-Bénard convection.” 2011. Web. 15 Jun 2019.

Vancouver:

Perkins AC. Mechanisms of instability in Rayleigh-Bénard convection. [Internet] [Doctoral dissertation]. Georgia Tech; 2011. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/42768.

Council of Science Editors:

Perkins AC. Mechanisms of instability in Rayleigh-Bénard convection. [Doctoral Dissertation]. Georgia Tech; 2011. Available from: http://hdl.handle.net/1853/42768

20. Rader, Jordan D. Thermal performance of gas-cooled divertors.

Degree: PhD, Mechanical Engineering, 2013, Georgia Tech

URL: http://hdl.handle.net/1853/49097

► A significant factor in the overall efficiency of the balance of plant for a future magnetic fusion energy (MFE) reactor is the thermal performance of… (more)

▼ A significant factor in the overall efficiency of the balance of plant for a future magnetic fusion energy (MFE) reactor is the thermal performance of the divertor. A significant fraction of the reactor power is delivered to the divertor as plasma impurities and fusion products are deposited on its surface. For an advanced MFE device, an average divertor heat load of 10 MW/m² is expected at steady-state operating conditions. Helium cooling of the divertors is one of the most effective ways to accommodate such a heat load. Several helium-cooled divertor designs have been proposed and/or studied during the past decade including the T-Tube divertor, the helium-cooled flat plate (HCFP) divertor, the helium-cooled multi-jet (HEMJ) divertor, the helium-cooled modular divertor with integral fin array (HEMP), and the helium-cooled modular divertor with slot array (HEMS). All of these designs rely on some form of heat transfer enhancement via impinging jets or cooling fins to help improve the heat removal capability of the divertor. For all of these designs very large heat transfer coefficients on the order of 50-60 kW/m²-K have been predicted. As the conditions of a fusion reactor and associated helium flow conditions (600 °C and 10 MPa) are difficult to achieve safely in a controlled laboratory environment, the study of these divertors often relies on computer simulations and experimental modeling at non-prototypical, albeit dynamically similar, conditions. Earlier studies were based on the assumption that, for geometrically similar divertor test modules, dynamic similarity can be achieved by matching only the Reynolds number. Experiments conducted in this investigation using different coolants and test module materials have shown this assumption to be false. Modified correlations for the Nusselt number and loss coefficients for the HEMJ and HEMP-like divertor modules have been developed. These have been used to develop generalized performance curves to predict the divertor performance, i.e. the maximum allowable heat flux and corresponding pumping power fraction, at prototypical conditions. Additionally, a numerical study has been performed to optimize the fin array geometry of the HEMP-like divertor module. The generalized correlations and performance curves developed in this investigation can be incorporated into system design codes, thereby allowing system designers to optimize the divertor geometry and operating conditions. Advisors/Committee Members: Abdel-Khalik, Said I. (advisor), Yoda, Minami (advisor), Ghiaasiaan, Seyed M. (committee member), Schatz, Michael (committee member), Stoesser, Thorsten (committee member).

Subjects/Keywords: Fusion; Thermal-hydraulics; Divertor; Plasma physics; Helium; Tungsten; Correlation; Gas cooled reactors; Nuclear reactors; Fusion reactors

…cartridge-in-shell design used by Hageman and Gayton at Georgia Tech. [29]… …36 Figure 26. Nu v. Re for T-Tube experiments performed by Crosatti at Georgia Tech showing… …performed at Georgia Tech in the last several years on the HEMJ, T-Tube, and HCFP have used a…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rader, J. D. (2013). Thermal performance of gas-cooled divertors. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/49097

Chicago Manual of Style (16^th Edition):

Rader, Jordan D. “Thermal performance of gas-cooled divertors.” 2013. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/49097.

MLA Handbook (7^th Edition):

Rader, Jordan D. “Thermal performance of gas-cooled divertors.” 2013. Web. 15 Jun 2019.

Vancouver:

Rader JD. Thermal performance of gas-cooled divertors. [Internet] [Doctoral dissertation]. Georgia Tech; 2013. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/49097.

Council of Science Editors:

Rader JD. Thermal performance of gas-cooled divertors. [Doctoral Dissertation]. Georgia Tech; 2013. Available from: http://hdl.handle.net/1853/49097

21. Kotas, Charlotte Walker. Acoustically induced fluid flows in a model fish ear.

Degree: PhD, Mechanical Engineering, 2008, Georgia Tech

URL: http://hdl.handle.net/1853/26695

► The fish ear contains three dense, bony bodies (otoliths) surrounded by fluid (the endolymph) and tissue. Under acoustic stimulation, the surrounding fluid and tissues oscillate… (more)

▼ The fish ear contains three dense, bony bodies (otoliths) surrounded by fluid (the endolymph) and tissue. Under acoustic stimulation, the surrounding fluid and tissues oscillate relative to the otoliths, stimulating the endolymph as well as the array of hair cell cilia adjacent to the otolith and embedded in tissue. It is believed that the hair cell cilia move with the surrounding fluid. This doctoral thesis studied the steady streaming (i.e., time-independent) component of the acoustically induced fluid motion inside of the fish ear to determine how the hair cell cilia displacements due to the steady streaming could provide acoustically relevant information to the fish. This research characterizes the fluid flow around oscillating model otoliths, namely spheroids, grooved spheroids, and a 350% scale model of a cod saccular otolith. This study models the otolithic endorgan as an oscillating body in a Newtonian fluid. The model ignores the surrounding tissues and assumes that the hair cell cilia move like the surrounding fluid. Particle pathline visualizations and particle-image velocimetry (PIV) are used to characterize the flow fields at various oscillation orientations, frequencies and amplitudes. These data are used to determine the location of the stagnation points on the body surface and at the boundaries of the inner rotating region of the flow. Studies are also conducted on bodies sinusoidally oscillated at both a single frequency and two (simultaneous) frequencies along the same direction. Both the steady streaming flow patterns and velocity fields are found to contain acoustically relevant information, but given the very small displacements associated with these flows, it is unclear if the steady streaming flows can be sensed by the fish ear. Advisors/Committee Members: Rogers, Peter (Committee Co-Chair), Yoda, Minami (Committee Co-Chair), Giddens, Don (Committee Member), Sotiropoulos, Fotis (Committee Member), Trivett, David (Committee Member), Yen, Jeanette (Committee Member).

Subjects/Keywords: Flow visualization; Acoustic streaming; Steady streaming; Fishes Physiology; Ear; Fluid mechanics; Fluid dynamics; Underwater acoustics

8 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Kotas, C. W. (2008). Acoustically induced fluid flows in a model fish ear. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/26695

Chicago Manual of Style (16^th Edition):

Kotas, Charlotte Walker. “Acoustically induced fluid flows in a model fish ear.” 2008. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/26695.

MLA Handbook (7^th Edition):

Kotas, Charlotte Walker. “Acoustically induced fluid flows in a model fish ear.” 2008. Web. 15 Jun 2019.

Vancouver:

Kotas CW. Acoustically induced fluid flows in a model fish ear. [Internet] [Doctoral dissertation]. Georgia Tech; 2008. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/26695.

Council of Science Editors:

Kotas CW. Acoustically induced fluid flows in a model fish ear. [Doctoral Dissertation]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/26695

22. Gandhi, Varun N. Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence.

Degree: PhD, Civil and Environmental Engineering, 2012, Georgia Tech

URL: http://hdl.handle.net/1853/45895

► The validation of UV reactors is currently accomplished by biodosimetry, in which the reactor is treated as a "black-box" and hence cannot account for the… (more)

▼ The validation of UV reactors is currently accomplished by biodosimetry, in which the reactor is treated as a "black-box" and hence cannot account for the dependence of the dose delivery on the complex hydrodynamics and the spatial variation in UV intensity. Alternative methods, such as fluorescent microspheres as non-biological surrogates and computational fluid dynamics (CFD) simulations, have been developed; however, each method has its shortcomings. In this study, a novel technique for the spatial and temporal assessment of the hydrodynamics and the UV dose delivered and the link between these two factors in a lab-scale UV reactor using three dimensional laser induced fluorescence (3DLIF) is developed. This tool can also be utilized for the optimization of UV reactors and to provide data for validation of CFD-based simulation techniques. Regions of optimization include areas around the UV lamp where short-circuiting occurred, a longer inlet approach section that enhances the performance of the reactor by reducing short circuiting paths and a longer outlet region to provide greater mixing. 3DLIF allows real time characterization of mixing and dose delivery in a single lamp UV reactor placed perpendicular to flow by capturing fluorescence images emitted from a laser dye, Rhodamine 6G, using a high speed CCD camera. In addition to three-dimensional mixing, the technique successfully visualized the two-dimensional, transient mixing behaviors such as the recirculation zone and the von Karman vortices and the fluence delivery within the reactor, which has not been possible with traditional tracer test techniques. Finally, a decomposition technique was applied to the flow and fluence delivery based concentration data to reveal similar structures that affect these phenomena. Based on this analysis, changing the flow in the reactor, i.e. the Reynolds number, will directly affect the fluence delivery. Advisors/Committee Members: Kim, Jaehong (Committee Chair), Linden, Karl (Committee Member), Pavlostathis, Spyros (Committee Member), Roberts, Philip (Committee Member), Stoesser, Thorsten (Committee Member), Yoda, Minami (Committee Member).

Subjects/Keywords: Laser induced fluorescence; Hydrodynamics; Spatial and temporal dose delivery; Proper orthogonal decomposition; UV disinfection; Ultraviolet radiation; Disinfection and disinfectants; Water Purification Disinfection; Water Purification Irradiation

10 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Gandhi, V. N. (2012). Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/45895

Chicago Manual of Style (16^th Edition):

Gandhi, Varun N. “Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence.” 2012. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/45895.

MLA Handbook (7^th Edition):

Gandhi, Varun N. “Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence.” 2012. Web. 15 Jun 2019.

Vancouver:

Gandhi VN. Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence. [Internet] [Doctoral dissertation]. Georgia Tech; 2012. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/45895.

Council of Science Editors:

Gandhi VN. Visualization and quantification of hydrodynamics and dose in UV reactors by 3D laser induced fluorescence. [Doctoral Dissertation]. Georgia Tech; 2012. Available from: http://hdl.handle.net/1853/45895

23. Fragkopoulos, Alexandros A. Toroidal instabilities in the presence of charge and non-Newtonian fluids.

Degree: PhD, Physics, 2017, Georgia Tech

URL: http://hdl.handle.net/1853/58655

► Cylindrical jets break into spherical droplets due to surface-tension driven, Rayleigh-Plateau instabilities. Interestingly, toroidal droplets can also transform into a spherical droplet via a shrinking… (more)

▼ Cylindrical jets break into spherical droplets due to surface-tension driven, Rayleigh-Plateau instabilities. Interestingly, toroidal droplets can also transform into a spherical droplet via a shrinking instability whereby the handle of the torus progressively disappears. We study this instability using particle image velocimetry and determining the velocity field inside the droplet. Using the experiments as a guide, we theoretically analyze the problem and account for the discrepancy between previous theoretical and simulation work. This allows elucidating which of the many possible modes controlling the toroidal droplet evolution are needed to capture the evolution and deformation of the droplet as seen experimentally. We then apply a voltage difference across the droplet and a controlled ground to charge the toroidal droplet. In this case, surface tension stresses compete with electrostatic stresses due to the presence of surface charge; qualitatively changing the behavior of the droplet, which, for sufficiently high voltages, is able to transition from a shrinking torus to an expanding torus. Remarkably, an additional transition happens at even higher voltages; in this case, the torus produces finger-like structures reminiscent of the Saffman-Taylor instability. Despite the three-dimensional character of our experiments, charge and geometry both combine to allow observing an instability that is most often seen in quasi-two dimensional situations. We study and model all these transitions, and identify the essential physics needed to describe them. Finally, we exploit that thin toroidal droplets approach the cylindrical limit to also study the effect of charge over jet break-up. We do this by comparing the experimentally determined wavelength associated to the fastest unstable mode to theoretical expectation for charged cylindrical jets. Furthermore, we study the break-up dynamics in the presence of rheologically non-linear materials. In this case, the droplets resist break-up for long times compare to when we use simple liquids. We show that we can explain our data by incorporating the non-linearities into a linear treatment of the problem through the strain-rate-dependent viscosity. Advisors/Committee Members: Fernandez-Nieves, Alberto (advisor), Goldbart, Paul M. (committee member), Yoda, Minami (committee member), Schatz, Michael F. (committee member), Burton, Justin C. (committee member).

Subjects/Keywords: Surface tension; Droplets; Tori; Charge; Non-Newtonian fluids; Geometry

11 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Fragkopoulos, A. A. (2017). Toroidal instabilities in the presence of charge and non-Newtonian fluids. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58655

Chicago Manual of Style (16^th Edition):

Fragkopoulos, Alexandros A. “Toroidal instabilities in the presence of charge and non-Newtonian fluids.” 2017. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/58655.

MLA Handbook (7^th Edition):

Fragkopoulos, Alexandros A. “Toroidal instabilities in the presence of charge and non-Newtonian fluids.” 2017. Web. 15 Jun 2019.

Vancouver:

Fragkopoulos AA. Toroidal instabilities in the presence of charge and non-Newtonian fluids. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/58655.

Council of Science Editors:

Fragkopoulos AA. Toroidal instabilities in the presence of charge and non-Newtonian fluids. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/58655

Georgia Tech

24. Weathers, James Brandon. Thermal Performance of Helium-cooled Divertors for Magnetic Fusion Applications.

Degree: MS, Mechanical Engineering, 2007, Georgia Tech

URL: http://hdl.handle.net/1853/16306

► The heat transfer performance of the Helium-cooled Multi-jet (HEMJ) divertor was investigated. The HEMJ design uses impinging jets to significantly enhance its heat transfer capability.… (more)

Subjects/Keywords: Plasma-facing component; Fusion reactors; Heat Transmission

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Weathers, J. B. (2007). Thermal Performance of Helium-cooled Divertors for Magnetic Fusion Applications. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/16306

Chicago Manual of Style (16^th Edition):

Weathers, James Brandon. “Thermal Performance of Helium-cooled Divertors for Magnetic Fusion Applications.” 2007. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/16306.

MLA Handbook (7^th Edition):

Weathers, James Brandon. “Thermal Performance of Helium-cooled Divertors for Magnetic Fusion Applications.” 2007. Web. 15 Jun 2019.

Vancouver:

Weathers JB. Thermal Performance of Helium-cooled Divertors for Magnetic Fusion Applications. [Internet] [Masters thesis]. Georgia Tech; 2007. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/16306.

Council of Science Editors:

Weathers JB. Thermal Performance of Helium-cooled Divertors for Magnetic Fusion Applications. [Masters Thesis]. Georgia Tech; 2007. Available from: http://hdl.handle.net/1853/16306

Georgia Tech

25. Gayton, Elisabeth Faye. Experimental and numerical investigation of the thermal performance of the gas-cooled divertor plate concept.

Degree: MS, Nuclear Engineering, 2008, Georgia Tech

URL: http://hdl.handle.net/1853/26517

► Experimental and numerical studies simulating the gas-cooled divertor plate design concept have been carried out. While thermo-fluid and thermo-mechanical analyses have been previously performed to… (more)

Subjects/Keywords: Porous media; Jet-impingement; CFD; FLUENT; Divertors; Plasma facing components; Fusion; Heat Transmission; Fusion reactors Cooling; Nuclear fusion

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Gayton, E. F. (2008). Experimental and numerical investigation of the thermal performance of the gas-cooled divertor plate concept. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/26517

Chicago Manual of Style (16^th Edition):

Gayton, Elisabeth Faye. “Experimental and numerical investigation of the thermal performance of the gas-cooled divertor plate concept.” 2008. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/26517.

MLA Handbook (7^th Edition):

Gayton, Elisabeth Faye. “Experimental and numerical investigation of the thermal performance of the gas-cooled divertor plate concept.” 2008. Web. 15 Jun 2019.

Vancouver:

Gayton EF. Experimental and numerical investigation of the thermal performance of the gas-cooled divertor plate concept. [Internet] [Masters thesis]. Georgia Tech; 2008. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/26517.

Council of Science Editors:

Gayton EF. Experimental and numerical investigation of the thermal performance of the gas-cooled divertor plate concept. [Masters Thesis]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/26517

Georgia Tech

26. Maini, Deepak. VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditons at the Interface: VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditions at the Interface.

Degree: MS, Mechanical Engineering, 2007, Georgia Tech

URL: http://hdl.handle.net/1853/16240

► A VOF based multiphase Lattice Boltzmann method that explicitly prescribes kinematic boundary conditions at the interface is developed. The advantage of the method is the… (more)

Subjects/Keywords: Volume of fluid; Multiphase flow; Lattice Boltzmann methods

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Maini, D. (2007). VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditons at the Interface: VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditions at the Interface. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/16240

Chicago Manual of Style (16^th Edition):

Maini, Deepak. “VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditons at the Interface: VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditions at the Interface.” 2007. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/16240.

MLA Handbook (7^th Edition):

Maini, Deepak. “VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditons at the Interface: VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditions at the Interface.” 2007. Web. 15 Jun 2019.

Vancouver:

Maini D. VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditons at the Interface: VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditions at the Interface. [Internet] [Masters thesis]. Georgia Tech; 2007. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/16240.

Council of Science Editors:

Maini D. VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditons at the Interface: VOF Based Multiphase Lattice Boltzmann Method Using Explicit Kinematic Boundary Conditions at the Interface. [Masters Thesis]. Georgia Tech; 2007. Available from: http://hdl.handle.net/1853/16240

Georgia Tech

27. Dickman, Brian D. Chemical and hydromechanical cue structure in the context of turbulent odor plume tracking.

Degree: PhD, Civil and Environmental Engineering, 2008, Georgia Tech

URL: http://hdl.handle.net/1853/26501

► The main focus of the current study was to quantify the chemical signals received by a blue crab (Callinectes sapidus) tracking a source in a… (more)

▼ The main focus of the current study was to quantify the chemical signals received by a blue crab (Callinectes sapidus) tracking a source in a laboratory flume. To make a direct linkage between tracking behavior and the odorant concentration signal, we developed a measurement system to quantify the instantaneous concentration field surrounding actively tracking blue crabs. A three-dimensional laser-induced fluorescence (3DLIF) system was designed and constructed to measure odorant concentrations around crabs tracking three source types: a continuous release with exit velocity matching the mean local velocity in the flume; a continuous release with a meander created by an upstream cylinder; and a pulsed release switching on and off and with the same mass flow rate as the other two plume types. The meandering and pulsed plumes were introduced to observe the effects of large-scale spatial (meandering) and temporal (pulsed) intermittency on crab tracking. Simultaneous with the chemical concentration measurements, crab position data was recorded for kinematic analysis during post-processing. In addition, concentration measurements were collected for the three plume types without crabs present in order to quantify the statistical characteristics of the plume structure The concentration signals arriving at the antennules and outer chemosensory organs, most notably the legs, were targeted due to the hypotheses that concentration bursts at the antennules mediate upstream movement and that spatial contrast at the leg chemosensors mediates turning. A sampling zone was placed in front of the crab's mouth parts and aligned with the crab carapace orientation to extract odorant bursts at the antennules. The data generally showed an increase in upstream walking speed when high concentration bursts arrive at the antennules location, which agrees with the hypothesis. Measurement of the odorant concentration at the outer chemosensors was less direct and involved placing a box upstream of the crab and sampled earlier in time in order to avoid shadowing interference. Based on the signal at the upstream sampling box, a general bias for turning was observed. Crabs casted transversely in response to the directional bias extracted from the upstream sampling box. A statistical analysis of crab behavioral response to concentrations at the antennules and outer chemosensors can be found in a (future) companion thesis written by Jennifer Page in the School of Biology. Data were also taken for the three plume types in the absence of blue crabs. The continuous plume average statistics displayed Gaussian behavior at nozzle centerline. The meandering plume data conformed to the meandering plume model of Gifford (1959), modified for an induced pseudo-periodic meander. The pulsed plume displayed characteristics intermediate between the cloud dispersion model (Townsend 1951, Chatwin and Sullivan 1979) and the Gaussian dispersion model for a continuous release. For the three plume types, the standard deviation of the concentration… Advisors/Committee Members: Roberts, Philip (Committee Member), Sturm, Terry (Committee Member), weissburg, marc (Committee Member), yoda, minami (Committee Member).

Subjects/Keywords: Blue crabs; 3-dimensional LIF; Turbulent mixing; Odor tracking; Blue crab Effect of odors on; Chemical senses

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Dickman, B. D. (2008). Chemical and hydromechanical cue structure in the context of turbulent odor plume tracking. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/26501

Chicago Manual of Style (16^th Edition):

Dickman, Brian D. “Chemical and hydromechanical cue structure in the context of turbulent odor plume tracking.” 2008. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/26501.

MLA Handbook (7^th Edition):

Dickman, Brian D. “Chemical and hydromechanical cue structure in the context of turbulent odor plume tracking.” 2008. Web. 15 Jun 2019.

Vancouver:

Dickman BD. Chemical and hydromechanical cue structure in the context of turbulent odor plume tracking. [Internet] [Doctoral dissertation]. Georgia Tech; 2008. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/26501.

Council of Science Editors:

Dickman BD. Chemical and hydromechanical cue structure in the context of turbulent odor plume tracking. [Doctoral Dissertation]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/26501

Georgia Tech

28. Islek, Akay A. (Akay Aydin). The Impact of Swirl in Turbulent Pipe Flow.

Degree: MS, Mechanical Engineering, 2004, Georgia Tech

URL: http://hdl.handle.net/1853/4955

► The impact of swirl (i.e., flow with axial and azimuthal velocity components) on the turbulent flow in a pipe is studied using two-component laser-Doppler velocimetry… (more)

Subjects/Keywords: Shape memory alloys; Refractive index matching; Laser Doppler velocimetry; Self-similarity; Fiber orientation; Wake; Swirl

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Islek, A. A. (. A. (2004). The Impact of Swirl in Turbulent Pipe Flow. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/4955

Chicago Manual of Style (16^th Edition):

Islek, Akay A (Akay Aydin). “The Impact of Swirl in Turbulent Pipe Flow.” 2004. Masters Thesis, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/4955.

MLA Handbook (7^th Edition):

Islek, Akay A (Akay Aydin). “The Impact of Swirl in Turbulent Pipe Flow.” 2004. Web. 15 Jun 2019.

Vancouver:

Islek AA(A. The Impact of Swirl in Turbulent Pipe Flow. [Internet] [Masters thesis]. Georgia Tech; 2004. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/4955.

Council of Science Editors:

Islek AA(A. The Impact of Swirl in Turbulent Pipe Flow. [Masters Thesis]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/4955

Georgia Tech

29. Li, Haifeng. An evanescent-wave based particle image velocimetry technique.

Degree: PhD, Mechanical Engineering, 2008, Georgia Tech

URL: http://hdl.handle.net/1853/26472

► Quantifying the velocity field near the wall in microfluidic devices is important because surface effects become significant at micro- to nanometer scales. Recent studies have… (more)

▼ Quantifying the velocity field near the wall in microfluidic devices is important because surface effects become significant at micro- to nanometer scales. Recent studies have suggested that the "no-slip" boundary condition breaks down in microscale flows of Newtonian liquids, where the amount of slip is usually extrapolated from velocity components measured far from the wall. This doctoral thesis presents a new technique, multilayer nano-particle image velocimetry (MnPIV), for measuring the tangential velocity components at different distances from and within about 500 nm of the wall and its application to measuring slip. The feasibility of MnPIV was demonstrated using synthetic images of plane Couette flow incorporating Brownian diffusion and imaging noise. The errors in MnPIV data were then quantified with Brownian dynamics simulations. Calibration experiments were used to correlate the image intensity of the tracer to its distance from the wall z. Multilayer nPIV was then used to determine the z-positions and distribution of the particles for z < 500 nm in experimental studies of microscale Poiseuille flow. The tracers were divided into three distinct layers based on their image intensities, and the average velocity of each layer was placed at the average z-position sampled by the particles in that layer. The resultant velocity gradients were within 6% on average of analytical predictions for 2D Poiseuille flow. Finally, the results of MnPIV studies of aqueous solutions flowing through microchannels with hydrophilic and hydrophobically-coated fused silica surfaces suggest that if the slip lengths are nonzero for both of these surfaces, they are less than the uncertainty in these results, or 27 nm and 31 nm for the hydrophilic and hydrophobic channels, respectively. Advisors/Committee Members: Yoda, Minami (Committee Chair), Aidun, Cyrus (Committee Member), Breedveld, Victor (Committee Member), Fedorov, Andrei (Committee Member), Zhu, Cheng (Committee Member).

Subjects/Keywords: Microfluidics; Evanescent wave; Hindered Brownian diffusion; Shear stress; Slip; Particle image velocimetry; Microfluidic devices; Surface chemistry; Molecular dynamics; Fluid dynamics

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Li, H. (2008). An evanescent-wave based particle image velocimetry technique. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/26472

Chicago Manual of Style (16^th Edition):

Li, Haifeng. “An evanescent-wave based particle image velocimetry technique.” 2008. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/26472.

MLA Handbook (7^th Edition):

Li, Haifeng. “An evanescent-wave based particle image velocimetry technique.” 2008. Web. 15 Jun 2019.

Vancouver:

Li H. An evanescent-wave based particle image velocimetry technique. [Internet] [Doctoral dissertation]. Georgia Tech; 2008. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/26472.

Council of Science Editors:

Li H. An evanescent-wave based particle image velocimetry technique. [Doctoral Dissertation]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/26472

Georgia Tech

30. Harvey, Jeremy Paul. Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators.

Degree: PhD, Mechanical Engineering, 2003, Georgia Tech

URL: http://hdl.handle.net/1853/5305

► In this study the phenomenon of compressible flow and heat transfer in a porous media is modeled based on fundamental principles. The conservation equations for… (more)

▼ In this study the phenomenon of compressible flow and heat transfer in a porous media is modeled based on fundamental principles. The conservation equations for the two phases are transformed by the method of volume averaging which is an analytic method used to unite the microscale and macroscale effects characteristic to porous media flows. Unique to this analysis is that the model is valid for oscillatory, cryogenic flows such as that occurring in a regenerative cryogenic refrigerator such as a Pulse Tube Cryocooler (PTC.) In a PTC the forced flow drive oscillations in the regenerator create Reynolds numbers high enough such that microscale inertial effects dominate the momentum equation. This phenomenon, known as the Forchheimer Effect, can be predicted and modeled based solely on fundamental principles and the method of volume averaging. The coefficients that characterize the Forchheimer momentum equation are determined experimentally. In addition to pressure gradients, heat transfer within a porous media occurs due to temperature gradients. Conduction within the solid and fluid phases is made evident by volume averaging, but the determination of the conductivity coefficients requires numerical experiments and is unique to the geometry and conductivities of the two phases. Convection between the two phases is the dominant mode of heat transfer within the porous media. Determination of the convective heat transfer coefficient for a porous media requires physical experiments. Heat transfer and pressure gradients in the porous media are always competing effects leading to a model which requires coupling of the momentum and energy equations. These competing effects are united with the concept of entropy generation which relies on the second law of thermodynamics. All real processes generate entropy, and the most efficient processes which balance pressure gradients and heat transfer generate minimum entropy. This concept of minimum entropy generation is unique. As a result, minimum entropy generation should always be used as the criteria for thermodynamic optimization of thermohydraulic systems. Advisors/Committee Members: Desai, Prateen V. (Committee Chair), Ghiaasiaan, S. Mostafa (Committee Member), Kirkconnell, Carl S. (Committee Member), Morris, Jeffrey F. (Committee Member), Yoda, Minami (Committee Member).

Subjects/Keywords: Method of lines dispersion

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Harvey, J. P. (2003). Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/5305

Chicago Manual of Style (16^th Edition):

Harvey, Jeremy Paul. “Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators.” 2003. Doctoral Dissertation, Georgia Tech. Accessed June 15, 2019. http://hdl.handle.net/1853/5305.

MLA Handbook (7^th Edition):

Harvey, Jeremy Paul. “Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators.” 2003. Web. 15 Jun 2019.

Vancouver:

Harvey JP. Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators. [Internet] [Doctoral dissertation]. Georgia Tech; 2003. [cited 2019 Jun 15]. Available from: http://hdl.handle.net/1853/5305.

Council of Science Editors:

Harvey JP. Oscillatory compressible flow and heat transfer in porous media : application to cryocooler regenerators. [Doctoral Dissertation]. Georgia Tech; 2003. Available from: http://hdl.handle.net/1853/5305

		in
And / Or
		in
And / Or
		in
And / Or
		in

Open Access Theses and Dissertations