ME Theses and Dissertations
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Item The mixing of two co-axial jets in a tube(Wichita State University, 1962-05) Diven, James L.The objectives of this writing are: 1) to present, step by step, Pai's approximate procedure for the calculation of velocity profiles in the mixing region of co-axial jets; 2) to compare the theoretical velocity profiles with experimental velocity profiles obtained by Rachner and reported in Reference 10, and 3) to determine the limits and accuracy of Pai's theory.Item Flow of saturated water through pipes, L/D range from 10 to 160(Wichita State University, 1962-04) Fitzgerald, JR., Wayne Miles; Stuart, David O.The objective of this thesis was to expand the accumulated knowledge ln the field of two-phase flow of saturated water through pipes. The effect which a varying pipe length-to-diameter ratio, in the range of 10 to 160 (diameter equal to 0.275 inches), has on the flow characteristics was investigated. The slip ratio or relative velocity between the vapor and liquid phases and the velocity of the vapor phase were determined for a steady critical flow condition. Also, due to a suspected fallacy in the value of the slip ratio obtained by Croteau, Reference 3, a reevaluation or his data was accomplished. This experimental investigation was conducted utilizing the test equipment and instrumentation used by Croteau with the addition of a 11-tube, 60-inch mercury manometer bank and a Model 900 Polaroid Land Camera to obtain pressure profiles along the length of the test pipes.Item Role of multifunctional 3D structured conductive nanofibers for flexible and wearable health monitoring systems(Wichita State University, 2024-07) Yeasmin, Farzana; Asmatulu, RamazanThis study aimed to synthesize and manufacture electrically conductive electrospun fibers for wearable health monitoring devices. Wearable health monitoring devices are essential for early and quick detection of diseases. High electrical conductivity is crucial for their performance and fast response. Electrically conductive nanofibers have the potential to enhance the performance of wearable biosensors. In this study, 18 different nanofibers were synthesized by electrospinning. PAN, SPEEK, PVDF, and polystyrene fibers were prepared, and different weight ratios of PEG and PVP inclusions were added with PVDF and PS to make fibers hydrophilic. It was observed that both PVDF and PS fibers showed hydrophilic characteristics after adding hydrophilic polymers into the solution at a certain amount. The measured water contact angle (WCA) for many fibers was 0°. The synthesized fibers were then dip-coated in an electrically conductive PEDOT: PSS solution under different conditions. Ultrasonication and desiccation effects were applied to enhance the impact of the dip coating procedure. It was found that ultrasonication and desiccation effect during the dip coating process has an impact on adsorbing the conductive solution and enhancing the electrical conductivity of the fibers. In this study, PAN fiber showed the highest electrical conductivity of 23.08 S/cm among all fibers. Polystyrene and PVDF-based fibers also showed good electrical conductivity of 17.52 S/cm and 6.72 S/cm, respectively. In this work, four-point probe test, WCA, FTIR, SEM, and EDS tests were performed to study fiber morphology. The conductive fibers prepared in this study have promising applications in wearable health monitoring devices and biosensors applications. This study may open novel opportunities for preparing electrically conductive fibers and their applications.Item PVDF and pan-based piezoelectric nanocomposite fibers integrated on fiber composites for improved vibration energy harvesting rates(Wichita State University, 2024-07) Todmal, Purva; Asmatulu, RamazanThis research explores the development and characterization of electrospun nanofibers integrated with fiber reinforced composites for effective vibration energy harvesting applications. Polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN) nanocomposite fibers were fabricated using electrospinning with piezoelectric inclusions such as lead zirconate titanate (PZT), barium titanate (BaTiO3), and zinc oxide (ZnO) to enhance their piezoelectric properties. The nanofibers were then integrated into 'open' and 'sandwich' composite configurations using glass, Kevlar, and carbon fiber prepregs. The energy harvesting tests showed that the PVDF+2 wt% BaTiO3 composite with glass prepregs in the open configuration exhibited the highest performance, achieving 22.4 V and 0.00853 W/m². PAN composites peaked at 13.6 V for PAN+2 wt% PZT with carbon prepregs, with a power density of 0.00315 W/m². Among the 'sandwich' composites, PVDF+4 wt% BaTiO3 with glass prepregs achieved 15.8 V and 0.00567 W/m², while PAN+4 wt% PZT with carbon prepregs reached 10.2 V and 0.00324 W/m². The 'sandwich' configuration generally showed lower performance due to reduced exposure of the piezoelectric fibers. Fourier Transform Infrared (FTIR) Spectroscopy confirmed the presence of the β-phase in PVDF, essential for piezoelectric properties, with significant peaks around 840 cm⁻¹, 1070 cm⁻¹, and 1170 cm⁻¹. FTIR also highlighted the structural integrity of PAN fibers, showing prominent nitrile stretching peaks at 2240-2260 cm⁻¹. PVDF nanofibers exhibited diameters ranging from 0.276 μm to 0.721 μm, while PVDF+4 wt% BaTiO3 fibers ranged from 0.377 μm to 2.456 μm, indicating substantial variability due to the inclusion aggregation. The PAN+4 wt% PZT fibers showed more uniform diameters ranging from 0.106 μm to 0.468 μm. This study provides valuable insights into optimizing nanofiber integrated composites for energy harvesting.Item Electrolytic reduction of carbon dioxide to formate/formic acid across various metallic electrodes utilizing high performance liquid chromatography for product analysis(Wichita State University, 2024-07) Egan, Connor; Gu, ShuangElectrolytic reduction of carbon dioxide is a unique reaction which can produce many different major products such as formate (HCOO−) and formic acid (HCOOH). The interactions between CO2 electrolytes and the metallic electrodes lead to formation of various unstable intermediates which cause the reaction mechanism branch into different pathways. Previous literature suggest that bismuth could be the best suited for forming formate/formic acid, however there are many other metals known for the same reaction. The research in this thesis specifically aims to 1) establish effective detection methods for low formate concentrations (at the level of mM) in the highly concentrated electrolyte (2 MKHCO3) by high-performance liquid chromatography (HPLC), and 2) to conduct the comparative study on the metallic wire electrodes in reducing CO2 to formate in a flow cell electrolyzer, based on the established HPLC methods. Two HPLC methods were established with very high coefficient of determination (R2 > 0.99) for two different HPLC columns: reversephase and anion-exchange. The comparative study on metal wire electrodes showed significant formate production from bismuth electrodes, however, other metals such as Sn-Bi alloy, Au, and Ag consistently provided higher formate production rates.