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2017

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Articles 1141 - 1170 of 1380

Full-Text Articles in Mechanical Engineering

High Strain-Rate Compressive Evaluation Of Pultruded Glass-Graphite/Epoxy Hybrid Composites Using Shpb & Dic Techniques, Suman Babu Ukyam, Damian Stoddard Jan 2017

High Strain-Rate Compressive Evaluation Of Pultruded Glass-Graphite/Epoxy Hybrid Composites Using Shpb & Dic Techniques, Suman Babu Ukyam, Damian Stoddard

Early Career Technical Journal (ECTJ)

Section 5: Materials; pp. 128-133


Indicators For Sustainability And Strategies For Implementation In The Area Of Vertical Transportation Techology, Magdelena Krstanoski Jan 2017

Indicators For Sustainability And Strategies For Implementation In The Area Of Vertical Transportation Techology, Magdelena Krstanoski

Early Career Technical Journal (ECTJ)

Section 6: Miscellaneous; pp. 145-152


Ensemble Calibration Of Hertzian Contact Parameters For A Discrete Element Model Of Sand, Gerald Pekmezi, David Littlefield Jan 2017

Ensemble Calibration Of Hertzian Contact Parameters For A Discrete Element Model Of Sand, Gerald Pekmezi, David Littlefield

Early Career Technical Journal (ECTJ)

Section 6: Miscellaneous; pp. 153-158


การจำลองแบบทางพลศาสตร์ของไหลเชิงคำนวณของของเหลวที่ไม่ละลายเข้าหากันในเครื่องปฏิกรณ์แบบจุลภาคที่ขยายขนาด, คณิน มงคล Jan 2017

การจำลองแบบทางพลศาสตร์ของไหลเชิงคำนวณของของเหลวที่ไม่ละลายเข้าหากันในเครื่องปฏิกรณ์แบบจุลภาคที่ขยายขนาด, คณิน มงคล

Chulalongkorn University Theses and Dissertations (Chula ETD)

สำหรับการสกัดด้วยตัวละลายในเครื่องปฏิกรณ์ขนาดจุลภาคนั้น ของเหลวในกระบวนการจะมีคุณสมบัติที่ไม่ละลายเข้าหากันซึ่งจะทำให้เกิดรูปแบบของการไหลที่แตกต่างกันออกไป โดยการไหลแบบ slug นั้นเป็นรูปแบบการไหลที่มักจะพบได้เมื่อเป็นการไหลที่ความเร็วต่ำ ซึ่งการไหลดังกล่าวสามารถรักษารูปแบบการไหลให้คงที่ตลอดความยาวท่อโดยที่มีประสิทธิภาพในการสกัดที่สูงกว่ารูปแบบการไหลแบบอื่นๆ ซึ่งเป็นผลจากการหมุนวนภายในเนื่องจากการเคลื่อนที่ของของเหลวภายใน slug การศึกษาการสกัดด้วยตัวทำละลายด้วยวิธีการดังกล่าวได้รับการยอมรับว่ามีประสิทธิภาพที่สูงเมื่อเปรียบเทียบกับวิธีการอื่นที่มีการใช้งานอยู่ในปัจจุบัน แต่ที่ผ่านมามักเป็นการศึกษาในระดับจุลภาคซึ่งมีผลผลิตโดยรวมน้อย ในงานวิจัยนี้ได้มุ่งไปที่การศึกษาผลเนื่องจากการเพิ่มขนาดเส้นผ่านศูนย์กลางของท่อในระดับมิลลิเมตร ที่มีต่อการเปลี่ยนแปลงรูปแบบการหมุนวนภายใน และความดันตกคร่อมภายใน slug โดยทำการศึกษาด้วยการจำลองแบบทางพลศาสตร์ของไหลเชิงคำนวณแบบ 2 มิติ ของการไหลผ่านท่อที่มีพื้นที่หน้าตัดเป็นรูปสี่เหลี่ยมที่มีขนาดแตกต่างกันออกไปตั้งแต่ 1-10 มิลลิเมตร ของเหลว 2 ชนิดที่มีคุณสมบัติการไม่ละลายเข้าหากันประกอบด้วยน้ำและเคโรซีนจะถูกป้อนเข้าสู่ท่อที่อยู่ตรงข้ามกันและเกิดการผสมกันที่บริเวณข้อต่อรูปตัว T โดยเปลี่ยนแปลงค่า Weber number ในช่วง 0.002-0.02 ผลการศึกษาแสดงให้เห็นว่าการเพิ่มขึ้นของขนาดเส้นผ่านศูนย์กลางท่อทำให้เวลาการหมุนวนลดลง 1.39% และความดันตกคร่อม slug ลดลง 85.12% โดยที่มีอัตราการไหลเชิงปริมาตรเพิ่มมากขึ้น อย่างไรก็ตามพบว่ารูปแบบการไหลแบบ slug จะไม่สามารถพบได้อีกต่อไปเมื่อเป็นการไหลในท่อที่มีขนาดเส้นผ่านศูนย์กลางมากกว่า 6 มิลลิเมตร


การออกแบบและผลิตเท้าเทียมแบบไดนามิคสำหรับผู้พิการขาขาดในระดับกิจกรรมปานกลาง, ดนุพงษ์ บุตรทองคำ Jan 2017

การออกแบบและผลิตเท้าเทียมแบบไดนามิคสำหรับผู้พิการขาขาดในระดับกิจกรรมปานกลาง, ดนุพงษ์ บุตรทองคำ

Chulalongkorn University Theses and Dissertations (Chula ETD)

ในปัจจุบัน ประเทศไทยมีผู้พิการขาขาดจำนวนมากและมีแนวโน้มที่จะเพิ่มจำนวนขึ้นอย่างต่อเนื่องในทุกๆ ปี หากแบ่งตามช่วงอายุของผู้พิการจะพบว่ามีผู้พิการขาขาดในกลุ่มวัยรุ่นถึงวัยกลางคนในช่วงอายุ 15 ถึง 44 ปี ประมาณร้อยละ 39 ของผู้พิการขาขาดทั้งหมด ซึ่งมีจำนวนมากกว่าช่วงอายุอื่นๆ ผู้พิการในกลุ่มนี้จะถูกจัดอยู่ในระดับกิจกรรมปานกลางหรือ K2-K3 ซึ่งเท้าข้างที่ยังเหลืออยู่ของผู้พิการในกลุ่มนี้สามารถปลดปล่อยพลังงานในการดีดตัวไปข้างหน้าที่เพียงพอต่อการเดินด้วยความเร็วเท่ากับคนปกติ อีกทั้งยังสามารถเคลื่อนไหวได้ดีทั้งในระนาบด้านหน้าและด้านข้าง จึงสามารถเดินบนพื้นที่มีความขรุขระหรือต่างระดับได้เป็นอย่างดี แต่ทว่าผู้พิการในกลุ่มนี้ยังคงใช้เท้าเทียมที่มีบริจาคในประเทศซึ่งมีข้อเท้าแข็งเกร็ง ไม่สามารถงอและปลดปล่อยพลังงานในการดีดตัวได้เหมือนเท้าคนปกติ งานวิจัยนี้จึงมีเป้าหมายที่จะออกแบบและผลิตเท้าเทียมแบบไดนามิคสำหรับผู้พิการขาขาดในระดับกิจกรรมปานกลาง ซึ่งสามารถเก็บสะสมพลังงานในจังหวะดีดตัวได้อย่างเหมาะสม และเคลื่อนไหวได้ทั้งในระนาบด้านข้างและด้านหน้า โครงสร้างเท้าเทียมถูกออกแบบโดยใช้วิธีการไฟไนต์เอลิเมนต์เพื่อวิเคราะห์การเก็บสะสมพลังงานและการเคลื่อนไหวให้เหมาะสมกับการใช้งานของผู้พิการในระดับกิจกรรมปานกลางและวิเคราะห์ความแข็งแรงตามแนวทางมาตรสากล ISO10328 โดยจะออกแบบให้มีพลังงานที่เก็บสะสมมากกว่าเท้าเทียมในท้องตลาดเล็กน้อยเพื่อให้พลังงานที่ปลดปล่อยสูงกว่าและใกล้เคียงกับคนปกติ ใช้แนวคิดการออกแบบแบบผ่าครึ่งซีกที่ส้นเท้าและเซาะร่องที่ปลายเท้าช่วยให้เคลื่อนไหวได้ในระนาบด้านหน้า โครงสร้างหลักของเท้าเทียมทำจากวัสดุผสมคาร์บอนไฟเบอร์มีความแข็งแรงสูงและน้ำหนักเบา ซึ่งผลิตโดยใช้วิธีการอบขึ้นรูปแบบสุญญากาศที่ควบคุมความดันและอุณหภูมิ เท้าเทียมต้นแบบได้รับการทดสอบการทำงานและทดสอบการเก็บสะสมและปลดปล่อยพลังงานของเท้าเทียมด้วยวิธีการทดสอบทางกล พบว่าสามารถเก็บพลังงานปลดปลอดพลังงานได้ 0.167 และ 0.137 J/kg ตามลำดับและมีมุมงอเท้าในทิศงอลง, งอขึ้น และพลิกด้านข้างของส้นและปลายเท้าเป็นมุม 8.96 องศา,16.98 องศา, 5.72 องศา และ 7.1 องศา ตามลำดับ ซึ่งเหมาะสมกับการใช้งานของผู้พิการขาขาดในระดับกิจกรรมปานกลาง อีกทั้งยังผ่านการทดสอบความแข็งแรงตามแนวทางมาตรฐานสากล ISO 10328:2006


Error Mapping Of Build Volume In Selective Laser Melting, Ninad Kulkarni Jan 2017

Error Mapping Of Build Volume In Selective Laser Melting, Ninad Kulkarni

Masters Theses

“Selective laser melting is one of the commonly used additive manufacturing processes employed for production of functional part. Therefore, quality aspects such as dimensional accuracy have become a point of great interest. Like all of the other additive manufacturing processes selective laser melting process suffers from the issue if having wide range of process parameters making the process control a complex task. Additionally, issues specific to the selective laser melting process such as position dependency of accuracy of the part, makes it difficult to predict the resulting dimensional inconsistencies in the part manufactured by this processes. This research is an …


Design And Analysis Of A Passive Heat Removal System For A Small Modular Reactor Using Star Ccm+, Raymond Michael Fanning Jan 2017

Design And Analysis Of A Passive Heat Removal System For A Small Modular Reactor Using Star Ccm+, Raymond Michael Fanning

Masters Theses

"Next generation nuclear power plants, specifically small modular reactor designs, are the best alternative to fossil fuels for power generation due to their power density and low carbon emissions and constant awareness of safety concerns. A promising safety feature of new designs is the removal of heat by passive systems in accident scenarios. The passive systems require no moving parts and no intervention by personnel. These systems must be accurately simulated for better understanding of the heat transport phenomena: natural convection cooling. Due to the fact that most work developing these passive heat removal systems are proprietary information, a passive …


Bio-Inspired Flow Fields For Pem Fuel Cells- Decoupling Pressure And Distribution Effects On Performance And Identifying Design Opportunities, Joshua David Heck Jan 2017

Bio-Inspired Flow Fields For Pem Fuel Cells- Decoupling Pressure And Distribution Effects On Performance And Identifying Design Opportunities, Joshua David Heck

Masters Theses

"The performance of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) is significantly impacted by flow distributor geometry. The effects of flow distributor geometry on PEMFCs was explored in two ways in this study. Firstly, the relative effects of pressure and distribution characteristics of different flow fields on fuel cell unit and system level performance were considered. A method of decoupling these effects was proposed and demonstrated by application to the traditional serpentine and parallel flow field designs.The performance of these two designs were modeled computationally and it was shown that, of the 17% better performance of the serpentine design, 12% was …


Cathodic Protection Measurement Through Inline Inspection Technology Uses And Observations, Briana Ley Ferguson Jan 2017

Cathodic Protection Measurement Through Inline Inspection Technology Uses And Observations, Briana Ley Ferguson

Masters Theses

"This research supports the evaluation of an impressed current cathodic protection (CP) system of a buried coated steel pipeline through alternative technology and methods, via an inline inspection device (ILI, CP ILI tool, or tool), in order to prevent and mitigate external corrosion. This thesis investigates the ability to measure the current density of a pipeline's CP system from inside of a pipeline rather than manually from outside, and then convert that CP ILI tool reading into a pipe-to-soil potential as required by regulations and standards. This was demonstrated through a mathematical model that utilizes applications of Ohm's Law, circuit …


Cyber-Physical Manufacturing Cloud: An Efficient Method Of Building Digital Twin For 3d Printer By Adapting Mtconnect Protocol, Liwen Hu Jan 2017

Cyber-Physical Manufacturing Cloud: An Efficient Method Of Building Digital Twin For 3d Printer By Adapting Mtconnect Protocol, Liwen Hu

Masters Theses

"The common modeling of a virtual machine is using an information model to describe the physics of machines. The integration of digital twins into productive cyber-physical cloud manufacturing (CPCM) systems imposes strict requirements such as reducing overhead and saving resources for the systems. In this paper, we investigate a new method for building cloud-based digital twins (CBDT), which can be adapted to the CPCM platform. Our method helps reduce computing resources in the processing center and guarantees the fastest speed of the interactions between the human users and physical machines. We introduce a knowledge resource center (KRC) built on a …


Diffusion And Mechanical Characterization Of Nanoparticle-Enabled Diffusion Controlled Materials, Joseph Louis Volpe Jan 2017

Diffusion And Mechanical Characterization Of Nanoparticle-Enabled Diffusion Controlled Materials, Joseph Louis Volpe

Masters Theses

"Nanoparticle-enabled diffusion control has been shown to rapidly refine multiphase microstructures during slowly cooled casting. This thesis characterizes the diffusion and the mechanical properties of nanoparticle-enabled diffusion controlled materials. To characterize diffusion properties, in situ characterization is performed to verify the nanoparticle enabled diffusion control mechanism. Materials with nanoparticles were observed to decrease the diffusion coefficient by at least one order of magnitude under similar melting conditions as compared to materials without nanoparticles. To understand mechanical properties, the nanoparticles that assembled at the growing interface were characterized under mechanical tensile stress. Nanoparticle-enabled interfaces were observed to improve the interface bond …


Dynamic Electromechanical Characterization Of Ferroelectrics At Cryogenic Temperatures, William Kent Hays Jan 2017

Dynamic Electromechanical Characterization Of Ferroelectrics At Cryogenic Temperatures, William Kent Hays

Masters Theses

"Electromechanical coupling in ferroelectric materials has given rise to a myriad of technological applications. Through the complex domain structure of ferroelectrics materials, which are typically stiff and have low damping, can exhibit significant structural damping. The applications for a material with a relatively large Young’s modulus and the ability to damp out vibrations would be useful for structures, more specifically, aerospace structures. The dynamic mechanical properties of ferroelectrics, particularly mechanical properties while an electric field is applied, are not well understood. This is due in part to the lack of experimental methods to measure such properties. Even with recent advancements …


Wrinkling Of Functionally Graded Sandwich Structures Subject To Biaxial And In-Plane Shear Loads, Harold Costa Jan 2017

Wrinkling Of Functionally Graded Sandwich Structures Subject To Biaxial And In-Plane Shear Loads, Harold Costa

Masters Theses

"Benefits of a functionally graded core increasing wrinkling stability of sandwich panels have been demonstrated in a recent paper [1] where a several-fold increase in the wrinkling stress was observed, without a significant weight penalty, using a stiffer core adjacent to the facings. In the present paper wrinkling is analyzed in case where the facings are subject to biaxial compression and/or in-plane shear loading and the core is arbitrary graded through-the-thickness. Two issues addressed are the effect of biaxial or in-plane shear loads on wrinkling stability of panels with both graded and ungraded core and the verification that functional grading …


Ti-Fe Intermetallics Analysis And Control In Joining Titanium Alloy And Stainless Steel By Laser Metal Deposition, Wei Li Jan 2017

Ti-Fe Intermetallics Analysis And Control In Joining Titanium Alloy And Stainless Steel By Laser Metal Deposition, Wei Li

Masters Theses

"Direct fusion joining titanium alloy and stainless steel can cause brittle Ti-Fe intermetallics which compromise the mechanical properties of diffusion bonds between titanium alloys and stainless steel. Therefore, filler metals are required as transition layers. In this research, stainless steel metallic powder was directly deposited on the titanium alloy substrate by laser beam, the Ti-Fe intermetallic phases formed in this process were investigated through analyzing fracture morphology, phase identification, and Vickers Hardness Number (VHN). After that, Laser Metal Deposition (LMD) was applied to explore a new fabricating process to join Ti6Al4V and SS316. A transition composition route was introducedTi6Al4V → …


Development Of An Excel® Rocket Simulator For Application In Middle School, High-School, And University Stem Education, Melvin Lee Hortman Jan 2017

Development Of An Excel® Rocket Simulator For Application In Middle School, High-School, And University Stem Education, Melvin Lee Hortman

All Master's Theses

Water rocket activities are one of the most popular STEM activities used in primary, secondary, and higher education yet are void of engineering, though engineering is heavily implied in the STEM acronym. This study investigated the amount of engineering present in water rocket activities, and options for emphasizing engineering more in water rocket activities using an open-platform flight simulator for use by educators to enable students to predict flight parameters of a water rocket they designed, and test those predictions against experimental data. The simulator was constructed in Excel® with many functions, but the function validated in this study was …


The Evaluation And Implementation Of Magnetic Fields Suitable For Biaxial Cyclic Testing Of Magnetorheological Elastomers, Dave Gorman Jan 2017

The Evaluation And Implementation Of Magnetic Fields Suitable For Biaxial Cyclic Testing Of Magnetorheological Elastomers, Dave Gorman

Doctoral

This thesis addresses the current lack of specification of magnetic fields currently used in the physical testing of Magnetorheological Elastomers MREs as well as providing the first comparative test results for MREs subject to both biaxial and uniaxial cyclic loading in the same magnetic field. In order to design an electromagnetic array capable of generating a suitable magnetic field for the cyclic biaxial testing of MREs, a review of currently used magnetic fields for uniaxial testing of MREs was carried out and a suitable array was modelled and evaluated with both 2D and 3D FEA software. Once the FEA analysis …


Computational Studies On Biomechanics Of Concussion And On Efficacy Of Football Helmets, David Labyak Jan 2017

Computational Studies On Biomechanics Of Concussion And On Efficacy Of Football Helmets, David Labyak

Dissertations, Master's Theses and Master's Reports

Football helmets have been used for many years to prevent head injuries to players. Over the years, the helmet design has evolved from a crude leather head covering to the more recent form fitting helmets that are seen today. The one design feature that has been common in the majority of all helmets is a hard polycarbonate shell with a foam cushion padding. The main goal of the padding layer was to reduce the amount of linear acceleration during an impact event. The one feature that has been overlooked is how stiff the padding is in rotation.

The purpose of …


Utilizing Reprap Style 3d Printers For The Manufacturing Of Composite Heat Exchangers, John Laureto Jan 2017

Utilizing Reprap Style 3d Printers For The Manufacturing Of Composite Heat Exchangers, John Laureto

Dissertations, Master's Theses and Master's Reports

The low cost 3D printing market is currently dominated by the application of RepRap (self-replicating rapid-prototyper) variants. Presented in this document are practical utilizations of RepRap technology. Developed are innovative processes to manufacture composite materials systems for thermal management solutions.

First, a laser polymer welder system is validated by quantifying maximum peak load and weld width of linear low density polyethylene (LLDPE) lap welds as a function of linear energy density. The development of practical engineering data, in this application, is critical to producing mechanically durable welds. Developed laser and printer parameter sets allow for manufacturing of LLDPE multi-layered heat …


A Study Of High Temperature Heat Pipes And The Impact Of Magnetic Field On The Flow Of Liquid Metal, Udit Sharma Jan 2017

A Study Of High Temperature Heat Pipes And The Impact Of Magnetic Field On The Flow Of Liquid Metal, Udit Sharma

Dissertations, Master's Theses and Master's Reports

A study of high temperature heat pipe was conducted to understand its characteristics. A review of working fluid, temperature, wick structure, problems, operational limit and applications was done. Alkali metal were concluded as the most viable candidate for the working fluid.

The impact of three parameters namely magnetic field, heat flux and temperature was analyzed on the performance of HTHP (High Temperature Heat Pipe). The presence of magnetic field had the most considerable impact on reducing the pumping limit of the heat pipe while the temperature had almost negligible effect. Magnetic field results in the pressure drop and adversely affect …


Advanced Uses For Carbon Nanotubes: A Spherical Sound Source And Hot-Films As Microphones, Micaela M. Thiery Jan 2017

Advanced Uses For Carbon Nanotubes: A Spherical Sound Source And Hot-Films As Microphones, Micaela M. Thiery

Dissertations, Master's Theses and Master's Reports

Super-aligned carbon nanotube (CNT) thin-film is used to create thermophones. The thermal properties of CNT film allow it to rapidly heat and cool when supplied AC power producing temperature and pressure gradients and, therefore, audible sound. The advantages of CNT thermophones include eliminating all moving components of traditional speakers and reducing the weight of the speaker itself by using CNT film, which is nearly weightless. Additionally, the flexibility of CNT film provides the unique opportunity to construct loudspeakers of various sizes and geometries. In this work, a spherical CNT thermophone is designed, manufactured, and tested for directivity with the overall …


Analysis Of Aeroelastic Effects On The 3-Dimensional Interference Of Wind-Turbine Rotors, Anurag Rajan Jan 2017

Analysis Of Aeroelastic Effects On The 3-Dimensional Interference Of Wind-Turbine Rotors, Anurag Rajan

Dissertations, Master's Theses and Master's Reports

Greater penetration of wind energy demands better utilization of available wind. This has led to a formidable increase in the rotor diameter over the past few years. Bigger rotors call for lighter, more flexible blades to reduce loads and improve fatigue life. As a result, future blades will deform substantially more than the relatively stiff blades of the past. More efficient use of wind power also calls for incorporating advanced active and passive control strategies and increasing the range of velocities over which wind energy is captured. Hence an improvement in the quality of numerical simulations capable of capturing the …


Control Of A Powered Ankle-Foot Prosthesis: From Perception To Impedance Modulation, Guilherme Aramizo Ribeiro Jan 2017

Control Of A Powered Ankle-Foot Prosthesis: From Perception To Impedance Modulation, Guilherme Aramizo Ribeiro

Dissertations, Master's Theses and Master's Reports

Active ankle prostheses controllers are demonstrating gaining smart features to improve the safety and comfort offor users. The perception of user intention to modulate the ankle dynamics is a well-known example of such feature. But not much work focused on the perception of the environment, nor how the environment should be included in the mechanical design and control of the prosthesisprostheses. The proposed work aims to improve the feasibility of integrate the environment perception integration intoto the prostheses controllersler, and to define the desired ankle dynamics, as mechanical impedance, duringof the human walk on different environmental settings. As a preliminary …


Model-Based Control Of An Rcci Engine, Akshat Abhay Raut Jan 2017

Model-Based Control Of An Rcci Engine, Akshat Abhay Raut

Dissertations, Master's Theses and Master's Reports

Reactivity controlled compression ignition (RCCI) is a combustion strategy that offers high fuel conversion efficiency and near zero emissions of NOx and soot which can help in improving fuel economy in mobile and stationary internal combustion engine (ICE) applications and at the same time lower engine-out emissions. One of the main challenges associated with RCCI combustion is the difficulty in simultaneously controlling combustion phasing, engine load, and cyclic variability during transient engine operations.

This thesis focuses on developing model based controllers for cycle-to-cycle combustion phasing and load control during transient operations. A control oriented model (COM) is developed by using …


Multiscale Modeling: Thermal Conductivity Of Graphene/Cycloaliphatic Epoxy Composites, Sorayot Chinkanjanarot Jan 2017

Multiscale Modeling: Thermal Conductivity Of Graphene/Cycloaliphatic Epoxy Composites, Sorayot Chinkanjanarot

Dissertations, Master's Theses and Master's Reports

The thermal property of epoxy as the binder in the Carbon Fiber (CF) composites, especially thermal conductivity is important to achieve the advance technology and to improve the performance of materials. Multiscale modeling including molecular dynamic (MD) modeling and micromechanical modeling is used to study the properties of neat Cycloaliphatic Epoxies (CE) and Graphene nanoplatelet (GNP)/CE with and without covalent functionalization.

The thermal properties (glass-transition temperature, thermal expansion coefficient, and thermal conductivity) and mechanical properties of CE system are investigated by MD modeling using OPLS-All Atom force field. A unique crosslinking technique is developed to achieve the cured CE models …


Modeling Mass And Thermal Transport In Thin Porous Media Of Pem Fuel Cells, Vinaykumar Konduru Jan 2017

Modeling Mass And Thermal Transport In Thin Porous Media Of Pem Fuel Cells, Vinaykumar Konduru

Dissertations, Master's Theses and Master's Reports

Water transport in the Porous Transport Layer (PTL) plays an important role in the efficient operation of polymer electrolyte membrane fuel cells (PEMFC). Excessive water content as well as dry operating conditions are unfavorable for efficient and reliable operation of the fuel cell. The effect of thermal conductivity and porosity on water management are investigated by simulating two-phase ow in the PTL of the fuel cell using a network model. In the model, the PTL consists of a pore-phase and a solid-phase. Different models of the PTLs are generated using independent Weibull distributions for the pore-phase and the solid-phase. The …


Development Of An Evaporation Sub-Model And Simulation Of Multiple Droplet Impingement In Volume Of Fluid Method, Sathya Prasad Potham Jan 2017

Development Of An Evaporation Sub-Model And Simulation Of Multiple Droplet Impingement In Volume Of Fluid Method, Sathya Prasad Potham

Dissertations, Master's Theses and Master's Reports

Droplet collision and impingement on a substrate are widely observed phenomenon in many applications like spray injection of Internal Combustion Engines. Existing Lagrangian models do not provide a comprehensive picture of the outcome of these events and may involve model constants requiring experimental data for validation. Physics based models like Volume of Fluid (VOF) method involve no parametric tuning and are more accurate. The aim of this thesis is to extend the basic VOF method with an evaporation sub-model including an additional vapor phase and implement this model in an open source Computational Fluid Dynamics (CFD) software, OpenFOAM. The new …


Assessment Of Annular Flow Boiling In The Context Of Computational Fluid Dynamics (Cfd) Simulations, Experiments, And Existing Correlations, Hrishikesh Prasad Ranga Prasad Jan 2017

Assessment Of Annular Flow Boiling In The Context Of Computational Fluid Dynamics (Cfd) Simulations, Experiments, And Existing Correlations, Hrishikesh Prasad Ranga Prasad

Dissertations, Master's Theses and Master's Reports

The main objective of the current work is to achieve a better understanding – through modeling and simulation/programming activities – of annular flow-boiling and its applications based on a synthesis of Computational Fluid Dynamics (CFD) simulations, existing correlations, and experiments. A unique and rigorous 2-D CFD simulations technique was developed for annular flow-boiling to propose a correlation for convective component of Heat Transfer Coefficient (HTC) – defined here as flow-boiling in the absence of nucleation. To provide a context for the correlation structure of convective component of HTC, flow-physics details of annular flow-boiling and correlation structure (based on fundamental considerations) …


The Impact Of Water Injection On Spark Ignition Engine Performance Under High Load Operation, Jeremy Worm Jan 2017

The Impact Of Water Injection On Spark Ignition Engine Performance Under High Load Operation, Jeremy Worm

Dissertations, Master's Theses and Master's Reports

An experimental effort has been completed in which water injection was investigated as a means of enabling increases in engine output and high load efficiency. Water was injected into the intake port of a direct fuel injected, 4-cylinder, boosted engine with dual independent variable valve timing. The water was shown to increase volumetric efficiency and decrease the onset of knock which in turn enable more optimal combustion phasing. Both of these affects resulted increases in load of up to 5.5% at the same manifold pressure as the baseline case. The advancement of combustion phasing, combined with elimination of fuel enrichment …


Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune Jan 2017

Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune

Dissertations, Master's Theses and Master's Reports

Two electrospray sources were developed to operate on an ionic liquid ferrofluid; one source was a pressure‑fed capillary electrospray source and the other was a novel electrospray source which used a magnetically‑induced instability to produce a peak from which an electric field could extract electrospray. Multiple characteristics of electrospray operation were examined for both sources using faraday plates/cups, a quartz crystal microbalance, a retarding potential analyzer, and a time-of-flight mass spectrometer. The ILFF electrosprays for a capillary source were shown to operate in a mixed ion/droplet regime. The mass flow of the electrospray beam was primarily transported by larger particles …


Investigation Of Rope Formation In Gas–Solid Flows Through A 90° Pipe Bend Using High-Speed Video And Cfd Simulations, Sai S. Guda, Steven L. Rowan, Tao Yang Jan 2017

Investigation Of Rope Formation In Gas–Solid Flows Through A 90° Pipe Bend Using High-Speed Video And Cfd Simulations, Sai S. Guda, Steven L. Rowan, Tao Yang

Faculty & Staff Scholarship

A study of rope formation in gas–solid flows through abrupt turns has been conducted. Experiments in which high-speed video was recorded and analyzed for solid concentration profiles were compared to CFD simulations utilizing both RANS and large eddy simulation turbulence models. In both simulations and experiments, particle-laden flows of air and ground flaxseed, with solid loadings of 35, 42, and 51% were considered. The results of the study demonstrate that both RANS and large eddy simulation can accurately predict particle roping. Furthermore, simulations show that the roping phenomenon is strongly dependent upon selection of an appropriate value for the coefficient …