Mechanical Engineering Commons^™

Design Of Metallic Bipolar Plates For Pem Fuel Cells, Sriram Praneeth Isanaka, Austin Das, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This project focused on the design and production of metallic bipolar plates for use in PEM fuel cells. Different metals were explored and stainless steel was found out to be best suited to our purpose. Following the selection of metal, it was calculated that to produce 0.7 W of power, the bipolar plate should have an active surface of 25cm2. The bipolar plates were designed with different flow field patterns and manufactured. Different flow field patterns that were used were the straight design, serpentine, multiple serpentine, pintype, interdigitated design and other custom designs. These plates were then assembled along with …

Improving The Efficiency Of Turbocharged Spark Ignition Engines For Passenger Cars Through Waste Heat Recovery, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The turbocharged direct injection stoichiometric spark ignition gasoline engine has less than Diesel full load brake engine thermal efficiencies and much larger than Diesel penalties in brake engine thermal efficiencies reducing the load by throttling. This engine has however a much better power density, and therefore may operate at much higher BMEP values over driving cycles reducing the fuel economy penalty of the vehicle. This engine also has the advantage of the very well developed three-way catalytic converter after treatment to meet future emission regulations. in these engines the efficiency may be improved recovering the waste heat, but this recovery …

Kers Braking For 2014 F1 Cars, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Small, high power density turbocharged engines coupled to kinetic energy recovery systems are one of the key areas of development for both passenger and racing cars. in passenger cars, the KERS may reduce the amount of thermal energy needed to reaccelerate the car following a deceleration recovering part of the braking energy. This translates in a first, significant fuel energy saving. Also considering the KERS torque boost increasing the total torque available to accelerate the car, large engines working at very low brake mean effective pressures and efficiencies over driving cycles may also be replaced by small higher power density …

Simulation And Testing Of Polymer Electrolyte Membrane Fuel Cell Bipolar Plates Fabricated By Selective Laser Sintering, M. Wu, Ming-Chuan Leu, N. Guo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Polymer Electrolyte Membrane (PEM) fuel cell converts directly electrochemical energy into electricity. Flow channels in bipolar plates, a critical component of fuel cell, were designed, simulated and tested. the bipolar plate used a mixture of graphite materials and was fabricated using a Selective Laser Sintering (SLS) process. the fabricated green parts were carbonized at high temperatures and converted into brown parts. Infiltration of resin was used to enhance the electric conductivity and strength of the bipolar plate. Finite element simulations were performed to investigate the state of species (hydrogen, oxygen) in the channels and Gas Diffusion Layers (GDLs) for four …

Energy Recovery In Passenger Cars, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The turbocharged direct injection stoichiometric spark ignition gasoline engine has less than diesel full load brake engine thermal efficiencies and much larger than diesel penalties in brake engine thermal efficiencies reducing the load. This engine has, however, a much better power density, and therefore may operate at much higher brake mean effective pressure (BMEP) values over driving cycles thus reducing the fuel economy penalty of the vehicle. This engine also has the advantage of the very well developed three-way catalytic (TWC) converter after treatment to meet future emission regulations. Replacement of fossil gasoline with renewable gasoline-like fuels has major advantages. …

Numerical Study Of Pressure Fluctuations Due To High-Speed Turbulent Boundary Layers, Lian Duan, Meelan M. Choudhari, Minwei Wu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by fully developed turbulence in supersonic turbulent boundary layers with an emphasis on both pressure fluctuations at the wall and the acoustic fluctuations radiated into the freestream. The wall and freestream pressure fields are first analyzed for a zero-pressure gradient boundary layer with Mach 2.5 and Reynolds number based on momentum thickness of approximately 2835. The single and multi-point statistics reported include the wall pressure fluctuation intensities, frequency spectra, space-time correlations, and convection velocities. Single and multi-point statistics of surface pressure fluctuations show good agreement with measured data …

Effects Of Riblets On Skin Friction And Heat Transfer In High-Speed Turbulent Boundary Layers, Lian Duan, Meelan M. Choudhari

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations of spatially developing turbulent boundary layers over riblets are conducted to examine the effects of riblets on skin friction and heat transfer at high speeds. Zero-pressure gradient boundary layers under two flow conditions (Mach 2.5 with Tw/Tr = 1 and Mach 7.2 with Tw/Tr = 0.5) are considered. Simulations are conducted for boundary-layer flows over a clean surface and symmetric V-groove riblets. The DNS results at Mach 2.5 confirm the few existing experimental observations and show that a drag reduction of approximately 7% can be achieved for riblets with proper spacing. The comparisons in turbulence statistics and …

100% Lpg Long Haul Truck Conversion - Economy And Environmental Benefits, Alberto A. Boretti, Charles Grummisch

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Advanced Vehicle Technologies (AVT), a Ballarat Australia based company, has developed the World's first diesel to 100% LPG conversion for heavy haul trucks. There is no diesel required or utilized on the trucks. the engine is converted with minimal changes into a spark ignition engine with equivalent power and torque of the diesel. the patented technology is now deployed in 2 Mercedes Actros trucks. the power output in engine dynamometer testing exceeds that of the diesel (in excess of 370 kW power and 2700 Nm torque). in on-road application the power curve is matched to the diesel specifications to avoid …

Design Of Rankine Cycle Systems To Deliver Fuel Economy Benefits Over Cold Start Driving Cycles, Alberto A. Boretti, Azmi Osman, Ishak Aris

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Prior papers have shown the potentials of gasoline-like internal combustion engines fitted with waste heat recovery systems (WHR) to deliver Diesel-like steady state fuel conversion efficiencies recovering the exhaust and the coolant waste heat with off-the-shelf components. in addition to the pros of the technology significantly increasing steady state efficiencies - up to 5 % in absolute values and much more in relative values - these papers also mentioned the cons of the technology, increased back pressures, increased weight, more complex packaging, more complex control, troublesome transient operation, and finally the cold start issues that prevent the uptake of the …

Generating Tones With A Vibrato Effect, M. Nakagawa, Shun Takai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Provided are a method, computer storage device, and tone control device for generating tones with a vibrato effect. A determination is made of a key depression interval comprising a difference of a current time of a current note from a previous time of a previous note. A performance mode is set to a single tone mode, in which only one note is generated, or a polyphonic mode, in which multiple notes are simultaneously generated, based on the determined key depression interval. The tone is generated to output the current note with a first modulation magnitude in response to determining that …

Development Of Kinectᵀᴿ Applications For Assembly Simulation And Ergonomic Analysis, Chinmay Prakash Daphalapurkar

Masters Theses

"Marker-less motion capture technology has been harnessed for several years to track human movements for developing various applications. Recently, with the launch of Microsoft Kinect, researchers have been keenly interested in developing applications using this device. Since Kinect is very inexpensive (only $110 at the time of writing this thesis), it is a low-cost and a promising substitute for the comparatively expensive marker-based motion capture systems. Though it is principally designed for home entertainment, numerous applications can be developed with the capabilities of Kinect. The skeleton data of a human being tracked by a single Kinect device is enough to …

Process Planning And Control Of Functionally Graded Parts Using Freeze-Form Extrusion Fabrication, Bradley Kenneth Deuser

Masters Theses

"Freeze-form Extrusion Fabrication (FEF) is an additive manufacturing technology that is capable of fabricating complex three-dimensional parts. FEF works by depositing an aqueous-based colloidal ceramic or metal paste in a layer-by-layer fashion below the freezing point of the aqueous medium as to rapidly freeze the paste. The FEF machine in the present study is equipped with three syringes and is capable of mixing each paste in a desired composition ratio by using an inline static mixer. Compensation for the transport delay caused by the static mixer is necessary; therefore, an algorithm was developed to apply a one-dimensional (1D) composition gradient …

Methods Of Optimizing The Gas Exchange Process To Improve Fuel Efficiency Of Small Carbureted Spark Ignition Engines, Cory Hannibal Huck

Masters Theses

"Fuel efficiency of internal combustion engines long has been a topic of concern. Much effort has been made to optimize the fuel efficiency of large automotive type engines. However, for small engine manufactures subject to tight cost constraints, this has only recently become an area of great focus. A method by which the fuel efficiency of an engine can be improved is through optimization of the intake process. Specifically, reductions in flow losses and the choice of appropriate valve event timings can provide ways to make gains towards more fuel efficient operation. The challenge arises when the focus is on …

Advanced Moisture Modeling Of Polymer Composites, Nathan Robert Roe

Masters Theses

"Composite materials absorb moisture from the environment and over time this moisture absorption affects the mechanical performance of the material. In order to determine the long-term moisture effects on the component, representative parts must be tested after having been exposed to an accelerated moisture-conditioning environment. This accelerated environment simulates the worst-case exposure conditions that a part might experience. Currently accepted methodologies for analyzing the time required to condition specimens are limited, only allowing simple geometry and an assumption that diffusivity rates are independent of the flow path or direction. Therefore, a more advanced finite element method is desired. In the …

A Novel Cantilever For Bi-Harmonic Atomic Force Microscopy, Muthukumaran Loganathan

Masters Theses

"Tapping mode (TM) AFM is a popularly used AFM technique in which an oscillating sharp tip mounted on a micro cantilever is used to probe the surface of interest with nanoscale resolution by making intermittent (tapping) contact with the surface. Any change in surface profile affects the tip amplitude, and is detectable only if it results in an amplitude change that is significant enough to be measured by the laser detector. Hence, it is desirable to have a micro cantilever that is sensitive to surface changes so as to provide sharper images and better surface resolution.

In the first part …

Design Of A Vortex Induced Vibration Based Marine Hydro-Kinetic Energy System, Varun Michael Lobo

Masters Theses

"Hydrokinetic energy harvesting based on vortex induced vibration (VIV) of a bluff body is discussed. VIV is defined as the vibration incurred on a bluff body due to an external fluid flowing over it. These vibrations are the results of boundary layer separation from the surface of the body. An optimized VIV generator has been developed, that utilizes a non-contact type linear magnetic device for generation of energy. The cylinder was chosen such that at the mass ratio (m*) was always lower than the critical mass (m*_critical= 0.52). The studies were based on two complementary …

Height Dependent Laser Metal Deposition Process Modeling, Patrick M. Sammons

Masters Theses

"Laser Metal Deposition (LMD) is used to construct functional parts in a layer-by-layer fashion. The heat transfer from the melt region to the solid region plays a critical role in the resulting material properties and part geometry. The heat transfer dynamics can change significantly as the layers increase, depending on the geometry of the sub layers. However, this effect is unaccounted for in previous analytical models, which are only valid for a single layer. This thesis develops a layer dependent model of the LMD process for the purpose of designing advanced layer-to-layer controllers. A lumped-parameter model of the melt pool …

Transient Growth And Instability Control Using Iteration-Varying Filter Ilc In Flexible Dual Flywheel System, Tong Mu

Masters Theses

"In the field of precision motion control, many industrial systems have flexible modes. This is especially true for very high performance nanopositioning systems where traditional bearing systems are replaced with flexible structures in order to eliminate sliding friction. The precision motion control is difficult in flexible systems because the rapid phase transition around the resonant frequency must be accurately modeled in order to actively control the resonant motion. In order to experimentally study the effectiveness of various control algorithms on flexible systems, a dual-flywheel flexible system is constructed. The mechatronics system design strategy is presented in this thesis. The control …

Development Of A Technique For Testing Of Tensile Properties With Miniature Size Specimens For Metal Additive Manufacturing, Sujitkumar Dongare

Masters Theses

"The study of mechanical properties of metals provides a basis to decide on the capability of a particular metal for a task and also to make predictions about its life. The concepts of stress, strain and strength of materials are employed in practically every engineering discipline. Mechanical properties such as stiffness, yield strength, tensile strength, ductility, toughness, impact resistance, creep resistance, fatigue resistance and others, influence the design, fabrication and service life of equipment. Therefore, more than one property is considered for the material selection process for an application. For complete understanding of any material and its feasibility for a …

Pulmonary Fluid Dynamics And Aerosol Drug Delivery In The Upper Tracheobronchial Airways Under Mechanical Ventilation Conditions, Timothy Andrew Van Rhein

Masters Theses

"The effects of mechanical ventilation conditions on fluid flow and particle deposition were studied in a computer model of the human airways. The frequency with which aerosolized drugs are delivered to mechanically ventilated patients demonstrates the importance of understanding the effects that ventilation parameters have on particle deposition in the human airways. Past studies that modeled particle deposition in silico frequently used an idealized geometry with steady inlet conditions. With recent advancements in computational power and medical imaging capabilities, studies have begun to use more realistic geometries or unsteady inlet conditions that model normal breathing. This study focuses specifically on …

Integration Of Multiple Vision Systems And Toolbox Development, Rohit Vijay Bapat

Masters Theses

"Depending on the required coverage, multiple cameras with different fields of view, positions and orientations can be employed to form a motion tracking system. Correctly and efficiently designing and setting up a multi-camera vision system presents a technical challenge. This thesis describes the development and application of a toolbox that can help the user to design a multi-camera vision system. Using the parameters of cameras, including their positions and orientations, the toolbox can calculate the volume covered by the system and generate its visualization for a given tracking area. The cameras can be repositioned and reoriented using toolbox to generate …

Enhancing The Aerodynamic Performance Of Stepped Airfoils, Ranganadhan Voona

Masters Theses

"The main objective of this research was to investigate the lift and drag characteristics of a stepped airfoil with backward facing steps; apply active flow control technique to enhance the aerodynamic performance of stepped airfoils and examine the possibility of using such airfoils on Unmanned Aerial Vehicles (UAV's). A step was introduced at mid-chord, with a depth of 50% of the airfoil thickness at mid-chord position extending till the trailing edge of a NACA 4415 airfoil. Computational studies were conducted with the use of passive flow control constituting the activation of step and active flow control with the use of …

Thermal Modeling And Analysis Of Polymer Electrolyte Membrane Open Cathode Fuel Cells, Blanca Ollero Loranca

Masters Theses

"In the past decade renewable energies have increasingly become a commodity in everyday life. Because of their high power densities and their application versatility, fuel cells have stood out among other sources of renewable energy. In order to improve this technology as the needs for it increases, thermal modeling is an essential step. Researchers in the past have investigated the effect that temperature has on fuel cells. However, not much work has been done on the thermal dynamics of these devices and no one, to the authors knowledge, has studied the speed of response in thermal changes as a function …

Control Oriented Thermal Modeling Of Lithium Ion Batteries, Derek Brown

Masters Theses

"Lithium ion batteries have been widely used in consumer electronics and are beginning to move to the forefront of the automotive and power grid industries. Lithium ion batteries are desirable in these applications because they are high energy density and high specific energy cells, while remaining inexpensive and lightweight. Safety is a concern in every consumer application; therefore, in order for lithium ion battery use to continue growing, advances in battery management systems are needed. Thermal management of lithium ion batteries is currently a critical issue. Applications are becoming more dependent on active liquid thermal management systems. The development of …

Fabrication Of Complex Ceramic Parts With Sacrificial Material Using Freeze-Form Extrusion Fabrication, Diego Armando Garcia MontañO

Masters Theses

"An additive manufacturing process called Freeze-form Extrusion Fabrication (FEF) was developed in this study to fabricate complex ceramic parts that require the use of sacrificial materials. The aqueous paste of alumina (Al₂O₃) was used as the main material, with solids loadings as high as 50 vol. % and water as the main liquid medium. Methyl cellulose, with a 10 vol. % solids loading and 90 vol. % water content, was used as the sacrificial material. The freeze-form extrusion machine has multiple extruders (extrusion devices) capable of fabricating parts from multiple materials without mixing them. The dynamic process of extruding alumina …

Generic Kinematic Simulation For Verification Of Laser Deposition Tool Paths, Sweta Dhaveji Chakravadhanula

Masters Theses

"The development of 3D visual simulation tool for machine simulation is a key approach in saving time and reducing cost. It is an important step before a manufacturing operation is performed on a part, as a tool to detect collision and validate the operation results. There are several kinds of manufacturing equipment being used and hence there is a need for the development of a generalized method to visually simulate a variety of machines. This paper presents the research conducted on describing machine configuration in a generic format which not only gives useful information, but can also be used as …

5-Axis Tool Path Generation With Collision Detection For Finish Machining Of Freeform Surfaces, Jomy Francis

Masters Theses

"Research in the field of Tool path generation for freeform surfaces has been done intensively in the past. However, the main challenge that still exists is the computational efficiency related to the tool path generation. Tool path generation for freeform surface involves instantaneous calculation of new tool orientations which does not collide with the neighboring surfaces. Since the collision check of tool and neighboring surface is done repetitively at every instant of the tool, the calculations at every instant are to be computationally as easy as possible.

This thesis is composed of one paper. Paper I presents a novel extension …

Ultrasonic Communications System For Health Monitoring Of Hydrokinetic Turbine Blades, Andrew James Heckman

Masters Theses

"A health monitoring approach is investigated for hydrokinetic turbine blade applications. In-service monitoring is critical due to the difficult environment for blade inspection and the cost of inspection downtime. Composite blade designs provide a medium for embedding sensors into the blades for in-situ health monitoring. The major challenge with in-situ health monitoring is transmission of sensor signals from the remote rotating reference frame of the blade to the system monitoring station. In the presented work, a novel system for relaying in-situ blade health measurements in hydrokinetic systems is described and demonstrated. An ultrasonic communication system is used to transmit health …

A Planning Tool To Predict The Welding Angle In Laser Metal Deposition, Sriram Prabhu

Masters Theses

"Research in Laser Metal Deposition (LMD) has been done rigorously in the past. However, the main challenge that still exists is the production of complex part geometries having overhang features. Production of such features requires individual tracks with a high aspect ratio and wider bead angle. The use of destructible/ non-destructible support structures involves costly post production operations which increase production cost. Tilting or moving the deposition surface can be useful to create overhangs but are applicable only to special cases. Since such techniques have to be used by the manufacturing community, the techniques need to be simple in calculation …

A Three-Dimensional Transient Simulation Of An Electrochemical Magnetohydrodynamics Cell With Micro And Millielectrode: A Unified Reconciliation Of Theory And Experiment, Cajon Gonzales

Masters Theses

"Even though electrochemically induced magnetohydrodynamic (MHD) convection is a straightforward inexpensive method for moving fluids in confined spaces as for example during electrodeposition, stripping voltammetry, or in microfluidics, efficient quantitative models only recently have begun to appear. This is traced to complex mathematics that have prevented development of analytical expressions, e.g., for mass-transfer limited currents in analogy to the well-known Levich equation for the rotating electrode. Thus, related literature expressions remain mainly phenomenological concerning particular cell geometries or applications. Here, using such reports as points of departure, we validate a computationally rigorous description of the magnetoelectrochemical problem and define the …