Master of Science, The Ohio State University, 2015, Aero/Astro Engineering

The development of flow blockage by particulate accumulation in the internal flow passages of a gas turbine double wall cooling scheme was studied experimentally. This parametric investigation focused on the effects of particle concentration, flow temperature, and particle size on the deposition characteristics in a cylindrical impingement/film cooling geometry. The impingement and film cooling hole layout is based on the leading edge cooling scheme of a modern nozzle guide vane (NGV). Tests were run at a constant pressure ratio of 1.02 (cavity pressure to exhaust) and the mass flow rate was permitted to decrease throughout the test as the cooling passages became obstructed. Particulate concentration was varied by holding the mass injected constant while adjusting the test injection time and rate. Particles consisted of Arizona Road Dust with distributions of 0-5, 0-10, and 0-20 µm. Flow blockage increased by 4% over a range of two orders of magnitude in particulate concentration for the smallest particle size distribution. At 452 °C the blockage levels increased to nearly four times that of the ambient conditions. Similar amounts of particulate deposited on the film cooling wall at ambient and high temperature, but the high temperature particulate caused greater blockage to the film holes. The effect of particle size was difficult to discern due to clumping of the smallest particles into large agglomerations. This clumping effect was coupled with the trend of increasing temperature. Implications for continued internal deposition research are discussed.

Committee: Jeffrey Bons Dr. (Advisor); Randall Mathison Dr. (Committee Member) Subjects: Aerospace Engineering; Fluid Dynamics; Mechanical Engineering

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

A ground-source heat pump (GSHP) system with an array of solar photovoltaic-thermal (PVT) modules for cooling-dominated buildings is proposed and its thermal performance is analyzed in this study. As individual systems, GSHP and PVT systems have experienced slow market penetration; GSHP systems have relatively high capital cost compared to conventional heating and cooling systems, while PVT systems have only seen niche application in low-carbon new residential buildings. Coupled together, the ground heat exchanger (GHX) could be designed to optimize efficiency of the PV cells, or the PVT array could be designed for thermal management of annual ground thermal load imbalances on the ground heat exchanger (GHX), or some combination of these design approaches. Radiative coolers have seen development and various applications in recent years. Using typical PVT collectors as a nocturnal cooler in addition to their daytime multi-function leads to better space and cost utilization of the PVT system. To examine the merit of such systems, an outdoor experiment was conducted to evaluate the PVT nocturnal performance, and two models were developed to simulate its thermal performance. First, mathematical model was developed with a detailed description of the physical and environmental parameters that affect the PVT nocturnal thermal performance. The mean error between the model and observed experimental data for predicting the fluid outlet temperature was 0.76 ± 0.91 K, indicating that the model is suitable to characterize the nocturnal cooling performance of the PVT module. The nocturnal radiative cooling is influenced by the water vapor content in the atmosphere and clear sky conditions. The nocturnal cooling power was found to increase by up to 45 W/m2 under a favorable radiative cooling condition. Due to the iterative nature of the detailed model, the model is computationally intensive when integrated in iterative system simulation such as the hybrid GSHP system. The detai (open full item for complete abstract)

Committee: Andrew Chiasson (Committee Chair); Rydge Mulford (Committee Co-Chair); Andrew Schrader (Committee Member); Atif Abueida (Committee Member) Subjects: Energy; Mechanical Engineering

PhD, University of Cincinnati, 2022, Engineering and Applied Science: Mechanical Engineering

The central idea of the present work is the study of thermoelectric (TE) transport phenomena in nonconventional materials including topological metals, shape memory alloys (SMA), and magnetic shape memory alloys (MSMA) to see how these properties evolve in such unusual materials. Topological materials are known for having unique transport properties because of their exotic band structures, while SMAs and MSMAs have structural and magnetostructural transformation respectively. TE and other related transport properties can provide insight of the underlying physics of transport in conducting materials, which becomes useful when potential applications of these materials are considered. For example, TE properties directly relate to the performance of these materials in TE power or cooling devices through a figure of merit. In (M)SMAs, TE properties can be used to directly find the structural and/or magnetic phase transformation temperatures, which in turn, dictate potential cooling applications: elastocaloric and magnetocaloric cooling in SMAs and MSMAs respectively. Hence, this work aims to investigate the characterization of TE properties in the aforementioned classes of materials. Each of the aforementioned cooling technologies have the potential to replace conventional vapor-compression technology in the future by eliminating the need for potentially harmful hydrofluorocarbons and many other refrigerants with high global warming potentials. Additionally, TE cooling devices provide solid-state, noiseless operation without any moving parts. However, this technology is still in its infancy and only low power TE cooling devices have been commercialized to this date. Major challenges in these non-conventional techniques include high material and device cost, and low energy efficiency. This demands significant improvements in both material development and model design of such non-conventional techniques to be able to compe (open full item for complete abstract)

Committee: Je-Hyeong Bahk Ph.D. (Committee Member); Raj Manglik Ph.D. (Committee Member); Kishan Bellur Ph.D. (Committee Member); Sarah Watzman Ph.D. (Committee Member) Subjects: Mechanical Engineering

MS, University of Cincinnati, 2020, Engineering and Applied Science: Mechanical Engineering

Regulation of brain temperature is critical for managing heat stress-related adverse events. It can be achieved by external cooling of the head. Head cooling systems that are lightweight, portable, and suitable for active work scenarios, such as firefighting, mining, and construction work, are currently unavailable on the market. This study proposes a novel active head cooling system that a) uses phase change material for thermal storage and b) can be designed for portability. The closed-loop bench-top system consists of two heat exchangers: a water-cooled heat exchanger with an attached heater, mimicking heat generated from the head, and a helical tube heat exchanger surrounded with ice as a heat sink. These heat exchanges are interconnected by tubing for water circulation. The system performance is assessed by the cooling duration that depends on the mass of ice used and the heat transfer rate. The system was evaluated for different heat loads varying from rest to exercise condition (20 W – 40 W) and flowrates (0.25 l/min – 0.65 l/min). The results show that the system can handle a heat generation rate of 40 W from the head for 100 min (for the flowrate of 0.25 l/min), which is about 3 times the safe duration of firefighting drills. The cooling time increases linearly with decreasing heat load: 138 min for 30 W and 190 min for 20 W, an increase of 38%, and 90%, respectively. It also increases with a decreasing flow rate. The range of Nusselt number for helical coil flow is about 4.4 – 6.8 times higher when compared to that of a straight pipe flow. The helical design of the heat exchanger leads to enhanced heat transfer owing to the formation of Dean's vortical flow. The results suggest that the head cooling system, having possible features of being portable, cost-effective, lightweight, and easy to use, can assist in the thermoregulation of brain temperature for workers during elevated thermal stress conditions.

Committee: Rupak Banerjee Ph.D (Committee Chair); Marwan Al-Rjoub Ph.D. (Committee Member); Je-Hyeong Bahk Ph.D. (Committee Member); Amit Bhattacharya Ph.D. (Committee Member); Michael Kazmierczak Ph.D. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2020, Mechanical Engineering

Gas turbine is an integrated part of modern aviation and power generation industry. The thermal efficiency of a gas turbine strongly depends on the turbine inlet temperature (TIT), and the turbine designers are continuously pushing the TIT to a higher value. Due to the increased freedom in additive manufacturing, the complex internal and external geometries of the turbine blade can be leveraged to utilize innovative cooling designs to address some of the shortcomings of current cooling technologies. The sweeping jet film cooling has shown some promise to be an effective method of cooling where the coolant can be brought very close to the blade surface due to its sweeping nature. A series of experiments were performed using a row of fluidic oscillators on a flat plate. Adiabatic cooling effectiveness, convective heat transfer coefficient, thermal field, and discharge coefficient were measured over a range of blowing ratios and freestream turbulence. Results were compared with a conventional shaped hole (777-hole), and the sweeping jet hole shows improved cooling performance in the lateral direction. Numerical simulation also confirmed that the sweeping jet creates two alternating vortices that do not have mutual interaction in time. When the jet sweeps to one side of the hole exit, it acts as a vortex generator as it interacts with the mainstream ow. This prevents the formation of the counter-rotating vortex pair (CRVP) and allows the coolant to spread in the lateral direction. The results obtained from the low speed at plate tests were utilized to design the sweeping jet film cooling hole for more representative turbine vane geometry. Experiments were performed in a low-speed linear cascade facility. Results showed that the sweeping jet hole has higher cooling effectiveness in the near hole region compared to the shaped hole at high blowing ratios. Next, a detailed experimental investigation of sweeping jet film cooling on the suction surface of a near engine scale (open full item for complete abstract)

Committee: Jeffrey Bons (Advisor); James Gregory (Committee Member); Randall Mathison (Committee Member); Ali Ameri (Committee Member) Subjects: Aerospace Engineering; Aerospace Materials; Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 2019, Mechanical Engineering

Heat transfer and pressure drop experiments were conducted for two gas turbine nozzle guide vane trailing edge designs. A circular pin fin array with clearance and a center-body (PFC) was designed and denoted as additive manufacturing-enabled design. The PFC design has two near wall channels with partial-length pins attached to the vane walls. Partial length pins have a gap to channel height ratio (G/H) of 0.23. Thermal performance and pressure ratio of the PFC design were compared to a conventional circular pin fin (PF) design. Test articles were additively manufactured using Stereolithography (SLA) and have identical pin diameters (D) as well as identical streamwise (X/D=1) and spanwise (S/D=2) spacing. Steady state heat transfer experiments were performed in a low speed linear cascade at low (Tu=6.1%) and high (Tu=14.3%) freestream turbulence intensities relevant to gas turbines. Infrared (IR) thermography was used to measure the trailing edge suction side wall temperature and overall cooling effectiveness (Φ) was estimated. Four different coolant mass flow rates were studied with Re based on pin diameter and inlet channel cross section just upstream of the pins of 820-1915 and 262-612 for the PFC and PF designs, respectively. As expected, cooling effectiveness nonlinearly increased with higher coolant mass flow rates. The PFC design has more uniform Φ in the region with partial-length pins than in corresponding locations of the PF design; implying that the PFC design would lead to less thermal stress than the PF design. The PFC design has slightly better thermal performance (≤4%) than the PF design at low Tu, except for the highest coolant mass flow rate. At low Tu, for the PFC design, coolant mass flow rate dependency of Φ was not as strong as in the PF design due to the flow passing through the clearance in the PFC design. At high Tu, the two designs show comparable thermal performance. Higher freestream turbulence intensity case exhibited higher overall cool (open full item for complete abstract)

Committee: Jeffrey P. Bons Professor (Advisor); Randall Mathison Assistant Professor (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

PhD, University of Cincinnati, 2018, Engineering and Applied Science: Metallurgical Engineering

A novel two-phase thermal solution, the Closed Loop Two-Phase Wicked Thermosyphon (CLTPWT), is introduced. This device was designed and tested by BritePointe Inc. for thermal management of high power light emitting diodes (LEDs) on factory floors. Contrary to conventional two-phase thermal management devices with micro-porous wick structures, this device operated based on a favorable hydrostatic potential provided by gravitational forces, and hence the name `Wicked Thermosyphon'. It has three sections – the evaporator, condenser, and sub-cooler. Water is employed as working fluid in this device. The steady-state operation is discussed in detail and mathematical models are developed to understand and predict steady-state performance. This includes developing steady-state energy, mass and pressure balance relationships on both the coil (condenser and sub-cooler together) and evaporator package sections. The effect of various void fraction correlations, from the literature, on the total mass of liquid in the condenser is studied. A natural convection heat transfer correlation on the air side is developed using steady-state temperature data for various operating powers (Qtherm) and is compared with available correlations from the literature (Hahne et al. [1]).

Committee: Frank Gerner PhD (Committee Chair); Michael Kazmierczak Ph.D. (Committee Member); Ahmed Shuja Ph.D. (Committee Member); Kumar Vemaganti Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science in Engineering, University of Akron, 2018, Mechanical Engineering

Battery Thermal Management Systems are necessary for the overall efficiency and life cycle of vehicle as well safety of passengers and vehicle, as elevated operating temperatures have adverse effect on the efficiency, life cycle and safety of the Li-ion battery packs. The operating temperature prescribed by many studies for improved performance and better life cycle of Li-ion batteries is around 25°C. In some worst case scenarios, high operating temperature may lead to thermal runaway in the battery, causing immense amount of heat generation, even leading to an explosion. To avoid all these dangerous events, battery thermal management is utilized to regulate the temperature of the battery pack. In this thesis, a novel battery thermal management system based on liquid cooling principle is proposed. The system involves dual purpose cooling plate for prismatic Li-ion batteries, which can maintain the temperature under normal conditions as well as mitigate the heat generated during thermal runaway. An experiment was performed on the prismatic Li-ion battery to measure the heat generation trends. The battery was discharged at 5C to replicate aggressive conditions. The data for maximum heat flux generated in the Li-ion battery was obtained. An estimated amount of heat generated during thermal runaway was calculated. A conjugate heat transfer method was used to simulate the cooling plates for normal operation and thermal runaway. The plates were simulated with two flow rates for normal operation and three flow rates for thermal runaway. Three different designs of cooling plates were compared on the basis of surface temperature, pressure drop and flow rate. The final design was selected based on the comparison with the rest of the cooling plates. The selected cooling plate can: • Maintain the temperature of battery below 25°C during normal operation. • Dissipate the maximum possible heat generated during thermal runaway and bring the temperature to less than 80°C. • M (open full item for complete abstract)

Committee: Siamak Farhad (Committee Chair); Gopal Nakarni (Committee Co-Chair); Alper Buldum (Committee Member); Reza Madad (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2017, Aero/Astro Engineering

Reverse-oriented film cooling, which consists of film cooling holes oriented to inject coolant in the opposite direction of the freestream, is experimentally and numerically investigated. Tests are conducted at various blowing ratios (M = 0.25, 0.5, and 1.0) under both low and high freestream turbulence (Tu = 0.4% and 13%), with a density ratio near unity. The interesting flow field that results from the reverse jet-in-crossflow interaction is characterized using flow visualization, particle image velocimetry, and thermal field measurements. Heat transfer performance is evaluated with adiabatic film effectiveness and heat transfer coefficient measurements obtained using infrared thermography. Adiabatic effectiveness results show that reverse film cooling produces very uniform and total coverage downstream of the holes, with some reduction due to increased freestream turbulence. The reverse film cooling holes are evaluated against cylindrical holes in the conventional configuration, and were found to perform better in terms of average effectiveness and comparably in terms of net heat flux reduction, despite augmented heat transfer coefficient. Compared to shaped hole data from the current study as well as previous literature, the reverse film cooling holes generally exhibited worse heat transfer performance. The aerodynamic losses associated with the film cooling are characterized using total pressure measurements downstream of the holes. Losses from the reverse configuration were found to be higher when compared to cylindrical holes in the conventional and compound angle configurations. To investigate the unsteady three-dimensional flow physics, large eddy simulations were conducted to replicate the experiment at all three blowing ratios, under low and high freestream turbulence. The models were first validated against the experimental measurements, before being used to provide insight into the complicated flowfield associated with the interaction between the reve (open full item for complete abstract)

Committee: Jeffrey Bons Dr. (Advisor); Mohammad Samimy Dr. (Committee Member); Randall Mathison Dr. (Committee Member) Subjects: Aerospace Engineering; Engineering

Doctor of Philosophy, The Ohio State University, 2016, Mechanical Engineering

An experiment was performed at The Ohio State University Gas Turbine Laboratory for a film-cooled high-pressure turbine stage operating at design-corrected conditions, with variable rotor and aft purge cooling flow rates. Several distinct experimental programs are combined into one experiment and their results are presented. Pressure and temperature measurements in the internal cooling passages that feed the airfoil film cooling are used as boundary conditions in a model that calculates cooling flow rates and blowing ratio out of each individual film cooling hole. The cooling holes on the suction side choke at even the lowest levels of film cooling, ejecting more than twice the coolant as the holes on the pressure side. However, the blowing ratios are very close due to the freestream massflux on the suction side also being almost twice as great. The highest local blowing ratios actually occur close to the airfoil stagnation point as a result of the low freestream massflux conditions. The choking of suction side cooling holes also results in the majority of any additional coolant added to the blade flowing out through the leading edge and pressure side rows. A second focus of this dissertation is the heat transfer on the rotor airfoil, which features uncooled blades and blades with three different shapes of film cooling hole: cylindrical, diffusing fan shape, and a new advanced shape. Shaped cooling holes have previously shown immense promise on simpler geometries, but experimental results for a rotating turbine have not previously been published in the open literature. Significant improvement from the uncooled case is observed for all shapes of cooling holes, but the improvement from the round to more advanced shapes is seen to be relatively minor. The reduction in relative effectiveness is likely due to the engine-representative secondary flow field interfering with the cooling flow mechanics in the freestream, and may also be caused by shocks and other compr (open full item for complete abstract)

Committee: Randall Mathison (Advisor); Michael Dunn (Committee Member); Sandip Mazumder (Committee Member); Jeffrey Bons (Committee Member) Subjects: Aerospace Engineering; Engineering; Mechanical Engineering

Doctor of Philosophy (PhD), Wright State University, 2012, Engineering PhD

The desire for high performance and low fuel consumption aero-engines has been pushing the limits of the turbomachinery and leading cutting-edge engine designs to fulfill the demand. The number of stages is reduced to achieve the same pressure ratios over lighter turbines. The extreme expansion requirements result in transonic-supersonic flow fields. Transonic and supersonic turbines are exposed to the shock waves that appear at the trailing edge of the airfoils, generating substantial efficiency deduction due to the interaction with the boundary layer. Furthermore, pressure fluctuations created by the shocks result in unsteady forcing on downstream components and eventually cause high cycle fatigue. Component failure may lead reduced service life and further damage on the engine. A novel proposal to control the resulting fish tail shock waves consists on, pulsating coolant blowing through the trailing edge of the airfoils. The changes in the base region topology and fish tail shock wave were numerically investigated for a wide range of purge flow at simplified blunt and circular trailing edge geometries. An optimum purge rate which increases the base pressure and significantly reduces the trailing edge shock wave intensity was found. The effects of pulsating base pressure on the shock properties and the base region was investigated in detail to understand the mechanisms driving the flow field under unsteady bleed. A linear cascade representative of modern turbine bladings was specifically designed and constructed. The test matrix comprised four Mach numbers, from subsonic to supersonic regimes (0.8, 0.95, 1.1 and 1.2) together with two engine representative Reynolds numbers (4 and 6 million) at various blowing rates. The blade loading, the downstream pressure distributions and the unsteady wall temperature measurements allowed understanding the effects on each leg of the shock structure. Minimum shock intensities were achieved using pulsating cooling. A substantia (open full item for complete abstract)

Committee: George Huang PhD (Advisor); Guillermo Paniagua PhD (Advisor); Joseph Shang PhD (Committee Member); Mitch Wolff PhD (Committee Member); Paul King PhD (Committee Member) Subjects: Aerospace Engineering; Engineering; Experiments; Fluid Dynamics; Mechanical Engineering

MS, University of Cincinnati, 2007, Engineering : Mechanical Engineering

The application of interest is the cooling of turbine blades in large gas combustion engines where hot gases from the combustor cause thermal deterioration of the metal turbine blades. A thin-film of coolant flow buffers the hottest parts of the blade surface. Heat transfer on a bluff body and, subsequently, a single-hole cooling problem is solved numerically in two-dimensions. The flow is assumed to be incompressible, and the laminar, steady Navier-Stokes equations are used to obtain the flow solution. Results for the bluff-body heat transfer agree very well with experimental data up to the separation point, and are within 20% of the data thereafter. The film-cooling simulation yielded higher cooling effectiveness due in large part to the use of the two-dimensional model, which treats the hole as a slot with higher coolant mass. Results from the simulations indicate that the Cobalt flow solver is capable of solving complex heat transfer problems.

Committee: Dr. Urmila Ghia (Advisor) Subjects: Engineering, Mechanical

PhD, University of Cincinnati, 2007, Engineering : Electrical Engineering

This dissertation describes the complete development of a very novel micro loop heat pipe. The activities described include the proof of concept research and convenes at the transition into commercial development. The proof of concept devices consisted of a small 1x1 cm. MEMS (micro electro mechanical systems) based silicon LHP cell that was developed and tested, which is intended as a pre-prototype for arbitrary lateral planar expansion in multiple cells for cooling electronic chips and other systems, in terrestrial and space applications (e.g. solar cell farms for energy beaming back to earth). The author as a member of a team of MEMS researchers and thermal science researchers, concentrated mainly on physical development, and measurement issues. The micro loop heat pipe is unique in that the wick is planar, is made of semiconductor grade silicon and is fabricated by the unique application of a photon pumped electrochemical etching (developed elsewhere for other applications but refined in this lab), locally referred to as “coherent porous silicon”. The resulting micro-capillary arrays were in the low micron range, with up to several million such through-capillaries per square centimeter. Also “quartz wool” has been demonstrated to serve well as a secondary or even primary wick with multi-micron effective pore size and porosity in the range of 95 percent. The author's major research contribution to this work was the refinement of the coherent porous silicon fabrication. A number of cps wicks were fabricated to act as the central component of the aforementioned LHP systems. The author also reveled and resolved multiple materials issues associated with the controlled micropatterening of the CPS wicks. This controlled micropatterening made it possible to carry out micro bonding of thermal pads/rails necessary for proper device operation. Cooling has been demonstrated up to about 60Watts/cm2, while maintaining top cap temperatures well below military specifications (open full item for complete abstract)

Committee: Dr. H. Henderson (Committee Chair); Dr. Frank Gerner (Other); Dr. Joseph Nevin (Other); Dr. Punit Boolchand (Other); Dr. Neville Pinto (Other); Dr. Charles Matthews (Other) Subjects:

Master of Science, The Ohio State University, 2010, Mechanical Engineering

As gas turbine engines are driven to be more efficient, quiet, and to produce less pollutant the turbine inlet temperature has a tendency to be driven upwards. The life of a turbine engine component decreases dramatically as the metal temperature increases. Because film cooling of high-pressure turbine airfoils has become common practice, improving the ability to predict film-cooling effectiveness is a critical problem of interest. Finding better, more efficient ways to use the cooling air is far preferable to using more of it. However, even if a given cooling-hole configuration proves to be effective in a flat-plate environment (which is the test article of interest in this thesis), it may not be effective on a turbine blade that is exposed to dynamic conditions that cannot be easily replicated. The goal of the experiment reported here is to measure the film effectiveness for a blowing ratio, temperature ratio and free stream Mach number, all similar to those experienced by the pressure surface of a rotating blade turbine blade with the same cooling-hole configuration, but for the flat-plate test article noted above. The cooling gas flow will be initiated earlier than the main flow to allow for proper setup of the cooling flow. This data will be used as a comparison to simulation results obtained using the CFD code Fine TURBO. It is shown in this work that the cooling-gas supply system interaction with the external gas supply associated with the blowdown facility process is not simple, and the current model used to design the experiment is not as good as it could have been. The effect of cooling was observed and the data closely resembled the simulations done using the CFD code Fine TURBO. Unfortunately, due to problems with the double-sided Kapton heat-flux gauges, heat flux data was not obtained in the immediate vicinity of the cooling holes. Solutions to the problems encountered in this experiment are relatively straightforward and are presented.

Committee: Michael Dunn Prof. (Advisor); Charles Haldeman Prof. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2009, Mechanical Engineering

As the demand for greater efficiency and reduced specific fuel consumption from gas turbine engines continues to increase, design tools must be improved to better handle complicated flow features such as vane inlet temperature distortions, film cooling, and disk purge flow. In order to understand the physics behind these features, a new generation of turbine experiments is needed to investigate these features of interest for a realistic environment.This dissertation presents for the first time measurements and analysis of the flow features of a high-pressure one and one-half stage turbine operating at design corrected conditions with vane and purge cooling as well as vane inlet temperature profile variation. It utilizes variation of cooling flow rates from independent circuits through the same geometry to identify the regions of cooling influence on the downstream blade row. The vane outer cooling circuit, which supplies the film cooling on the outer endwall of the vane and the trailing edge injection from the vane, has the largest influence on temperature and heat-flux levels for the uncooled blade. Purge cooling has a more localized effect, but it does reduce the Stanton Number deduced for the blade platform and on the pressure and suction surfaces of the blade airfoil. Flow from the vane inner cooling circuit is distributed through film cooling holes across the vane airfoil surface and inner endwall, and its injection is entirely designed with vane cooling in mind. As such, it only has a small influence on the temperature and heat-flux observed for the downstream blade row. In effect, the combined influence of these three cooling circuits can be observed for every instrumented surface of the blade. The influence of cooling on the pressure surface of the uncooled blade is much smaller than on the suction surface, but a local area of influence can be observed near the platform. This is also the first experimental program to investigate the influence of vane inlet (open full item for complete abstract)

Committee: Dr. Michael Dunn PhD (Advisor); Dr. Sandip Mazumder PhD (Committee Member); Dr. William Rich PhD (Committee Member); Dr. Mohammad Samimy PhD (Committee Member) Subjects: Fluid Dynamics; Mechanical Engineering

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

This thesis provides comprehensive insights into the optimization of thermoelectric (TE) systems for small scale energy generation and efficient air cooling and heating proposing new strategies that pave the way for more sustainable and efficient TE applications. The first project examines thermoelectric room air cooling and heating, focusing on a novel design model that optimize the coefficient of performance (COP) and cooling power, with extensive experimental verification based on Abhishek Saini's previous theoretical work [1]. This study focuses on air-to-air heat transfer configuration using a dual-sided TE cooling system with cost-effective design approach integrating commercially available TE modules with efficient heat exchangers and counterflow air streams. System-level evaluations validate the results, showing temperature differences, ?T, and COP across different currents and flow rates. A maximum cooling COP of 4.4 and a heating COP of about 6.5 at optimized current levels for the commercial TE modules were obtained and the analysis shows that parasitic thermal and electrical losses significantly reduced COP and temperature drop by over 50 %. Further optimization on cooling and heating, considering convection heat transfer, interface thermal conductance, and geometric factors like TE leg thickness and module fill factor, suggest potential to triple the temperature difference, increase COP by 1.5 times, and double performance through design adjustments. The second project explores a thermal analysis and simulation study on the impact of sidewall air cooling on the power output and efficiency of solar thermoelectric generators (STEGs) featuring a novel V-shaped TE design, previously introduced by Xinjie Li [2]. This V-shape TE design enables elimination of additional electrodes in the module to reduce electrical resistance and enhance voltage generation. The V-shaped legs not only act as TE elements, but also as heat sinks with sidewall air convecti (open full item for complete abstract)

Committee: Je-Hyeong Bahk Ph.D. (Committee Chair); Kishan Bellur Ph.D. (Committee Member); Sarah Watzman Ph.D. (Committee Member); Raj Manglik Ph.D. (Committee Member) Subjects: Engineering

Master of Science, The Ohio State University, 1962, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2008, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1966, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Landscape Architecture, The Ohio State University, 2024, Landscape Architecture

Extreme heat events have significant impacts on urban environments and their residents. They can shape the physical form of cities, influence urban planning and design, and even mold the cultural identity of urban communities. This thesis aims to investigate the interplay between extreme heat events, city formation, and cultural identity that happened in Jeddah, Saudi Arabia. Working methods for this study will be the development of a historical narrative through the lens of extreme heat and its impacts on urban form and patterns of urban behavior. The aim of this work is to understand Jeddah's history of responding to extreme heat over time, comprehend the factors exacerbating urban heat, and assess their impacts on society and the environment in order to design an ideal residential model tailored to Jeddah's climate and meeting housing needs. This model will be derived from lessons learned from literature review and precedent analysis that are tailored to Jeddah's climate with the ambition of producing a model that can mitigate the impact of climate change on the city and other urban areas facing extreme urban heat due to climate change.

Committee: Jacob Boswell (Advisor); Kristine Cheramie (Committee Member); Ujaan Ghosh (Committee Member); Kelsea Best (Committee Member); Andrew Cruse (Committee Member) Subjects: Landscape Architecture; Sustainability