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Articles 31 - 60 of 93
Full-Text Articles in Engineering
Determining The Mechanical Properties Of Lattice Block Structures, Nathan Wilmoth
Determining The Mechanical Properties Of Lattice Block Structures, Nathan Wilmoth
ETD Archive
Lattice block structures and shape memory alloys possess several traits ideal for solving intriguing new engineering problems in industries such as aerospace, military, and transportation. Recent testing at the NASA Glenn Research Center has investigated the material properties of lattice block structures cast from a conventional aerospace titanium alloy as well as lattice block structures cast from nickel-titanium shape memory alloy. The lattice block structures for both materials were sectioned into smaller subelements for tension and compression testing. The results from the cast conventional titanium material showed that the expected mechanical properties were maintained. The shape memory alloy material was …
Hybrid Position And Impedance Control Of A Forging Process, Derek Stake
Hybrid Position And Impedance Control Of A Forging Process, Derek Stake
ETD Archive
"Pick and place" robotic material handling has been a key to increase piece rates and reduced variability in forging processes. One of the drawbacks to current "pick and place" robotic material handling methods is the inability to locate the part after a forging operation and move it to the next position in a timely manner. If the billet changes position during the forging process, the manipulator will take longer to find the part and transfer it to the next station or the manipulator will be unable to move the part to the next position correctly which may cause scrap. Another …
Vibration Analysis Of Anisotropic Plates, Special Case: Violin, Chaitanya J. Lomte
Vibration Analysis Of Anisotropic Plates, Special Case: Violin, Chaitanya J. Lomte
ETD Archive
This thesis presents vibration analysis of the top plate of Stradivari violin by creating a 3D model using SolidWorks and finding mode shapes and natural frequencies using SolidWorks simulation. The top plate was affixed to the bottom plate via a side wall following the contour of the violin plates. Assuming the input excitation is sinusoidal, it was applied at the location of bridge where the strings rest on it.. The static component of the force was calculated to be 83.17 N. The first five natural frequencies of the violin top plate are in the range of 150 to 450 Hertz. …
Computational Study Of Savonius Wind Turbine, Asmita C. Chinchore
Computational Study Of Savonius Wind Turbine, Asmita C. Chinchore
ETD Archive
This project involves study of 2-Blade and 3-Blade Savonius vertical wind turbines positioned at different orientations. For a 2-Blade turbine the orientations considered were 0 degree, 45 degree, 90 degree and 135 degree in reference to the direction of the prevailing wind and for the 3-Blade turbine the orientations taken into account were 0 degree, 30 degree, 60 degree and 90 degree in reference to the direction of the prevailing wind. The basic aim of this thesis was to study how the two designs are different from each other and which design produces more power when applied with constant wind …
Aerodynamic Measurements Of A Variable-Speed Power-Turbine Blade Section In A Transonic Turbine Cascade, Ashlie B. Flegel
Aerodynamic Measurements Of A Variable-Speed Power-Turbine Blade Section In A Transonic Turbine Cascade, Ashlie B. Flegel
ETD Archive
The purpose of this thesis is to document the impact of incidence angle and Reynolds number variations on the 3-D flow field and midspan loss and turning of a 2-D section of a variable-speed power-turbine (VSPT) rotor blade. Aerodynamic measurements were obtained in a transonic linear cascade at NASA Glenn Research Center in Cleveland, OH. Steady-state data were obtained for ten incidence angles ranging from +15.8° to -51.0°. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12 ₉ 105 to 2.12 ₉ 106. Data …
Cfd And Heat Transfer Models Of Baking Bread In A Tunnel Oven, Raymond Matthew Adamic
Cfd And Heat Transfer Models Of Baking Bread In A Tunnel Oven, Raymond Matthew Adamic
ETD Archive
The importance of efficiency in food processing cannot be overemphasized. It is important for an organization to remain consumer- and business-oriented in an increasingly competitive global market. This means producing goods that are popular, of high quality and low cost for the consumer. This research involves studying existing methods of baking bread in a common type of industrial oven - the single level bread baking tunnel oven. Simulations of the oven operating conditions and the conditions of the food moving through the oven are performed and analyzed using COMSOL, an engineering modeling, design and simulation software. The simulation results are …
Free Convection Along A Vertical Wavy Surface In A Nanofluid, Deepak Ravipati
Free Convection Along A Vertical Wavy Surface In A Nanofluid, Deepak Ravipati
ETD Archive
The study of this paper is to introduce a boundary layer analysis for the fluid flow and heat transfer characteristics of an incompressible nanofluid along a vertical wavy surface in a nanofluid. The Resulting transformed governing equations are solved numerically by an implicit finite-difference scheme (Keller-Box method). The results are presented for the major parameters including the wave amplitude , buoyancy ratio parameter , Brownian motion parameter , Thermophoresis parameter and Lewis number. A systematic study on the effects of the various parameters of the local frication factor, surface heat transfer rate (Nusselt number) and mass transfer rate (Sherwood number) …
Computational Analyses For Fluid Flow And Heat Transfer In Different Curved Geometries, Carlin Miller Lucente
Computational Analyses For Fluid Flow And Heat Transfer In Different Curved Geometries, Carlin Miller Lucente
ETD Archive
Three-dimensional Computational Fluid Dynamics (CFD) models were developed to simulate fluid flow and heat transfer in a variety of helical channel geometries: circular and elliptical. Laminar flow was observed for Reynolds number between 200 and 1000. Code validation was done for developing steady laminar flow in a circular curved channel. The CFD results were compared to previous numerical results to verify that the model was producing valid results. The curve of the channel has a centrifugal effect on the fluid flow creating secondary flow known as Dean cells. This secondary flow moves the location of the maximum axial velocity towards …
Finite Element Analysis Of Spur Gear Set, V.S.N. Karthik Bommisetty
Finite Element Analysis Of Spur Gear Set, V.S.N. Karthik Bommisetty
ETD Archive
A Finite Element procedure has been developed in this work to determine the load distribution factor, Km, of the AGMA formula for a set of spur gear. At first, a spur gear with perfect involute is modeled using a 3-D CAD software. The model is them is assembled with shafts having 1, 2, and 3 degree misalignments. The generated 3-D models were in turn imported to ANSYS workbench to calculate the maximum bending and contact stresses using finite element method. The results generated were then compared with the maximum bending stress results obtained for parallel shafts to estimate the Load …
A Finite Element Approach To Stress Analysis Of Face Gears, Lokamanya Siva Manohar Rampilla
A Finite Element Approach To Stress Analysis Of Face Gears, Lokamanya Siva Manohar Rampilla
ETD Archive
Face Gears have alternative gear-teeth configuration compared to Bevel Gears. Face Gear have a standard spur pinion as opposed to a bevel Gear. This work concentrates on modeling of a Face-gear, Meshed with a spur gear, using CAD Software and Finite Elements Analysis. The bending stress developed at the gear teeth is determined. Numerical results are validated using the bending stress developed between two involute spur gears
Mathematical Modeling Of Dc Cardiac Ablation, Sowmya Reddy Narala
Mathematical Modeling Of Dc Cardiac Ablation, Sowmya Reddy Narala
ETD Archive
This thesis presents a mathematical modeling of the cardiac DC ablation procedure. The model treats the procedure as a one dimensional heat transfer phenomenon taking place across the thickness of the myocardium. The model further considers a constant 37 oC for one of the boundary condition of the affected tissue, and the temperature of the other boundary condition is set to be a time dependent square-pulse variations. The parameters defining this time dependent boundary condition is used to perform parametric studies to predict tissue temperature at different depth of the myocardium. The initial condition of the myocardium prior to the …
Modeling, Simulation And Experimental Verification Of An Electric Bicycle With Regenerative Braking, Maulik Kalolia
Modeling, Simulation And Experimental Verification Of An Electric Bicycle With Regenerative Braking, Maulik Kalolia
ETD Archive
Electric bicycles are widely available in user markets. However their use as a daily commuting vehicle is limited due to the need for frequent recharging. This thesis focuses on the mathematical modeling of electrical bicycle with regenerative breaking. Basic bond graphs methods are discussed here to develop state space models for mechatronic systems. A bond graph based mathematical model of an electric bicycle with regeneration is developed in this thesis. Mathematical models are tested in simulation, generating different road scenarios. Parameters required for the simulation are calculated using an experimental setup. The thesis shows the capability of bond graphs to …
Model Identification, Updating, And Validation Of An Active Magnetic Bearing High-Speed Machining Spindle For Precision Machining Operation, Adam C. Wroblewski
Model Identification, Updating, And Validation Of An Active Magnetic Bearing High-Speed Machining Spindle For Precision Machining Operation, Adam C. Wroblewski
ETD Archive
High-Speed Machining (HSM) spindles equipped with Active Magnetic Bearings (AMBs) are envisioned to be capable of autonomous self-identification and performance self-optimization for stable high-speed and high quality machining operation. High-speed machining requires carefully selected parameters for reliable and optimal machining performance. For this reason, the accuracy of the spindle model in terms of physical and dynamic properties is essential to substantiate confidence in its predictive aptitude for subsequent analyses.This dissertation addresses system identification, open-loop model development and updating, and closed-loop model validation. System identification was performed in situ utilizing the existing AMB hardware. A simplified, nominal open-loop rotor model was …
Probabilistic Structural And Thermal Analysis Of A Gasketed Flange, Atul G. Tanawade
Probabilistic Structural And Thermal Analysis Of A Gasketed Flange, Atul G. Tanawade
ETD Archive
Performance of a flange joint is characterized mainly by its 'strength' and 'sealing capability'. A number of analytical and experimental studies have been conducted to study these characteristics under internal pressure loading. However, with the advent of new technological trends for high temperature and pressure applications, an increased demand for analysis is recognized. The effect of steady-state thermal loading makes the problem more complex as it leads to combined application of internal pressure and temperature. Structural and thermal analysis of a gasketed flange was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties …
Probabilistic Stress Analysis Of Circular Fins Of Different Profiles, Sridhar Madhira Venkata
Probabilistic Stress Analysis Of Circular Fins Of Different Profiles, Sridhar Madhira Venkata
ETD Archive
The temperature distribution and thermal Stresses induced by a temperature difference for steady state heat transfer in silicon carbide (SiC) ceramic tube heat exchanger with circular fins was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for Hoop and Radial stresses due to the structural and thermodynamic random variables. These results are used to identify the most critical design variables in order to optimize the design and make it cost effective. The probabilistic analysis leads to the selection of the …
Cfd Simulations For The Effect Of Unsteady Wakes On The Boundary Layer Of A Highly Loaded Low Pressure Turbine Airfoil (L1a), Samuel J. Vinci
Cfd Simulations For The Effect Of Unsteady Wakes On The Boundary Layer Of A Highly Loaded Low Pressure Turbine Airfoil (L1a), Samuel J. Vinci
ETD Archive
The study of a very high lift, low-pressure turbine airfoil in the presence of unsteady wakes was performed computationally and compared against experimental results. The experimental data were collected in a low speed wind tunnel under high (4.9 ) and then low (0.6 ) freestream turbulence intensity conditions on a linear cascade with wakes that were produced from moving rods upstream of the cascade. The flow coefficient was kept at 0.7 while the rod to blade spacing was changed from 1 to 1.6 to 2 blade spacings. These cases were conducted for Reynolds number equal to 25,000 and 50,000, based …
A Cfd Model Of Mixing In A Microfludic Device For Space Medicine Technology, Terri Lynn Mckay
A Cfd Model Of Mixing In A Microfludic Device For Space Medicine Technology, Terri Lynn Mckay
ETD Archive
The DNA Medicine Institute (DMI) is currently developing a device to be used for blood analysis to satisfy the unique requirements of space medicine applications. A key component of that device is the micromixer, which will ensure mixing and dilution of reagents utilized for detection assays. As part of the device design process, the micromixer was modeled, and the mixing characteristics were analyzed and compared to experimental data. The experimental data was based on a top-view of the system and, lacking data throughout the fluid domain, could not provide the insight into the mixing process that modeling could readily provide. …
Fabrication And Testing Of A Nonstandard Thin-Film Heat Flux Sensor For Power System Applications, Scott D. Wilson
Fabrication And Testing Of A Nonstandard Thin-Film Heat Flux Sensor For Power System Applications, Scott D. Wilson
ETD Archive
Stirling convertors are being operated by NASA Glenn Research Center for many years to demonstrate a Radioisotope Power System (RPS) capable of providing reliable power for potential multi-year space missions. Techniques used to monitor Stirling convertors for change in performance include measurements of temperature, pressure, energy addition, and power output. It is difficult to measure energy addition to Stirling convertors due to the complex geometries of the hot components, temperature limits of sensor materials, and invasive integration of sensors. A thin-film heat flux sensor was used to directly measure heat energy addition to a Stirling convertor. The one micron thick, …
Evaluation Of Lean Systems In Rail Maintenance Operations, Mert Baykut
Evaluation Of Lean Systems In Rail Maintenance Operations, Mert Baykut
ETD Archive
The recognized strength of lean systems is its broad applicability to every process industry even though they include some complicated and time-intensive processes. However, this conception is based on the tools and philosophy of Lean systems and the nature of the industry. The required craftsmanship and repetitive processes in rail maintenance define the uniqueness of this research The objective of this thesis was to research the opportunities and applicability for lean systems in rail maintenance. During the research a unique system, consisting of Lean systems and systems engineering tools, is realized and tried to integrate instead of a pure Lean …
A Systems Engineering Reference Model For Fuel Cell Power Systems Development, T. L. Blanchard
A Systems Engineering Reference Model For Fuel Cell Power Systems Development, T. L. Blanchard
ETD Archive
This research was done because today the Fuel Cell (FC) Industry is still in its infancy in spite over one-hundred years of development has transpired. Although hundreds of fuel cell developers, globally have been spawned, in the last ten to twenty years, only a very few are left struggling with their New Product Development (NPD). The entrepreneurs of this type of disruptive technology, as a whole, do not have a systems engineering 'roadmap", or template, which could guide FC technology based power system development efforts to address a more environmentally friendly power generation. Hence their probability of achieving successful commercialization …
Fea Analysis Of Novel Design Of Cylindrical Roller Bearing, Prasanna Subbarao Bhamidipati
Fea Analysis Of Novel Design Of Cylindrical Roller Bearing, Prasanna Subbarao Bhamidipati
ETD Archive
This work presents a finite element stress analysis of a novel design of cylindrical roller. The focus of this study is to create a uniform contact-stress distribution along the length of the roller and to recommend a roller bearing design which is easier to fabricate. The new design relies on creating symmetric cylindrical cavities at both ends of a roller. The cavity is concentric with the main body of the roller. The new roller design reduces overall mass of the typical assembly with helps to improve bearing life and its overall performance. The FEA results published herein shows that new …
Vibratory Behavior Of Rolling Element Bearings: A Lagrangian Approach, Phani Krishna Kalapala
Vibratory Behavior Of Rolling Element Bearings: A Lagrangian Approach, Phani Krishna Kalapala
ETD Archive
Vibratory behavior of a rolling element bearing on a horizontal rotor is studied in this work. This Thesis analyzes the dynamics of a typical roller bearing as a result of internal excitations. These internal excitations stem from the geometric deviations of the interacting surfaces from their ideal geometry. Such deviations in turn are the results of either manufacturing limitations or normal wear of the bearing surfaces. Lagrangian approach is implemented to derive the dynamic equations of motion. Matlab is used to solve the equation of motion of governing the vibrations of the system. Parametric studies are conducted to provide results …
Adaptive Sliding Mode Control For Aircraft Engines, Kathryn C. Ebel
Adaptive Sliding Mode Control For Aircraft Engines, Kathryn C. Ebel
ETD Archive
Aircraft engine control has been evolving since its beginning. With advancements in technology more and more control methods are being applied to this area. This thesis presents the design of an adaptive PID sliding mode control (A-SMC) for a turbofan engine. The controller design methodology is presented. Using an aircraft engine simulation environment developed by NASA, called Commercial Modular Aero-Propulsion System Simulation, the developed controller is tested. The results from three simulations are analyzed to investigate the application of this new design scheme. The A-SMC is able to follow the demanded fan speed for short flight simulations. However, some of …
Multivariable Sliding Mode Control Design For Aircraft Engines, Sirirat Sangwian
Multivariable Sliding Mode Control Design For Aircraft Engines, Sirirat Sangwian
ETD Archive
Many control theories are used in controlling aircraft engines. However, the multivariablesliding mode control is not yet established in this application even though ithas a lot of potential in dealing with complex and nonlinear systems such as aircraftengines. Therefore, a guideline in developing multivariable sliding mode control law for an aircraft engine is presented in this thesis. The problem of chattering in thesliding mode control is suppressed by the use of the boundary layer method. The controllogic is tested by implementing NASA's Commercial Modular Aero-PropulsionSystem Simulation 40k (C-MAPSS40k). Simulation results are analyzed and comparedto the results obtained from the baseline …
Modeling And Performance Investigation Of A Rotor With Dissimilar Bearing Support System, Yunlu Li
Modeling And Performance Investigation Of A Rotor With Dissimilar Bearing Support System, Yunlu Li
ETD Archive
Different types of bearings have different dynamic characteristics. By using one type of bearing at one end of a rotor and another type of bearing at the other end of the rotor, it is possible to exploit the advantages of both types in the same system. One example of such combination is a bronze bushing and active magnetic bearing (AMB). In the available literature, there are examples of such systems but are not fully explored with regard to how to model the system to fully utilize both support type properties. This thesis investigates the modeling and performance of such a …
Application Of Active Magnetic Force Actuator For Control Of Flexible Rotor System Vibrations, Volodymyr Mykhaylyshyn
Application Of Active Magnetic Force Actuator For Control Of Flexible Rotor System Vibrations, Volodymyr Mykhaylyshyn
ETD Archive
The purpose of this work was to develop and experimentally demonstrate a novel approach to minimize lateral vibrations of flexible rotor. The applied feed forward control approach employed magnetic force actuator to inject a specially designed force to counteract the rotor unbalance force. By specific selection of frequency and phase as functions of the rotor running speed and rotor natural frequency, the proposed simplified injection waveform has been shown to be effective both in reducing the rotor's vibrations and for hardware implementation. A model of the test rig was constructed using the finite element (FE) method and was validated using …
A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control, Olga V. Kartuzova
A Computational Study For The Utilization Of Jet Pulsations In Gas Turbine Film Cooling And Flow Control, Olga V. Kartuzova
ETD Archive
Jets have been utilized in various turbomachinery applications in order to improve gas turbines performance. Jet pulsation is a promising technique because of the reduction in the amount of air removed from compressor, which helps to increase turbine efficiency. In this work two areas of pulsed jets applications were investigated, first one is film cooling of High Pressure Turbine (HPT) blades and second one is flow separation control over Low Pressure Turbine (LPT) airfoil using Vortex Generator Jets (VGJ) The inlet temperature to the HPT significantly affects the performance of the gas turbine. Film cooling is one of the most …
Thermal Analysis Of Natural Convectiona And Radiation In Porous Fins, Mehulkumar G. Maheria
Thermal Analysis Of Natural Convectiona And Radiation In Porous Fins, Mehulkumar G. Maheria
ETD Archive
No abstract provided.
Heat Transfer In A Nanofluid Flow Past A Permeable Continuous Moving Surface, Sarvang D. Shah
Heat Transfer In A Nanofluid Flow Past A Permeable Continuous Moving Surface, Sarvang D. Shah
ETD Archive
The main purpose of this paper is to introduce a boundary layer analysis for the fluid flow and heat transfer characteristics of an incompressible nanofluid flowing over a permeable isothermal surface moving continuously. The resulting system of non-linear ordinary differential equations is solved numerically using Runge-Kutta method with shooting techniques. Numerical results are obtained for the velocity, temperature and concentration distributions, as well as the friction factor, local Nusselt number and local Sherwood number for several values of the parameters, namely the velocity ratio parameter, suction/injection parameter and nanofluid parameters. The obtained results are presented graphically and in tabular form …
Natural Convection In A Porous Medium Saturated By Nanofluid, Kaustubh Ghodeswar
Natural Convection In A Porous Medium Saturated By Nanofluid, Kaustubh Ghodeswar
ETD Archive
A boundary layer analysis is presented for the natural convection heat and mass transfer flow past along two different geometries i.e., a vertical cone and an isothermal sphere in a Non-Darcy porous medium saturated with a nanofluid. A co-ordinate transformation is used to transform the governing equations into non-dimensional non-similar boundary layer equations. These equations are then solved numerically using implicit finite difference method (Keller-box method). Numerical solutions for heat transfer rate, mass transfer rate and friction factor have been presented for parametric variations of the buoyancy ratio parameter N-r, Brownian motion parameter Nb, thermophoresis parameter Nt and Lewis number …