Mechanical Engineering Commons^™

Dynamic Thermal Management Of Multi Core Processors Using Core Hopping, Avinash Raghu

Mechanical and Aerospace Engineering Theses - Archive

Multi core processors are the order of the day today. The demand for greater levels of performance and the consequent increase in design complexity have rendered the single core processor obsolete and resulted in more cores being put onto a single chip. Processors incorporating more than 4 cores on a chip are dubbed many core processors. This, while improving performance, has lead to increased power densities. Also, the power distribution across the die surface is not uniform. These factors together, result in heat being concentrated at specific points on the die surface, called `hot spots'.The increase in die temperature results …

Mean Pressure Measurements Of Micro-Vortex Generator At Mach 2.5, Yusi Shih

Mechanical and Aerospace Engineering Theses - Archive

Shock wave/boundary layer interactions (SBLIs) are always an important issue for high-speed vehicles. SBLIs reduce the performance of aerodynamic surfaces and engine inlets, amongst a number of adverse effects. Micro-vortex generators (MVGs) are a potential flow control method that has seen intense investigation recently and have even been implemented in actual configurations at low speeds. The present research is focused on the mean pressures at Mach 2.5 around an MVG. Experiments were performed with a baseline flat plate and also with two MVG configurations (70 and 45 trailing edge) mounted ahead of a 5° ramp. In the present study MVGs …

Axial Wave Propagation In Truncated Cones, Bhumil A. Diwanji

Mechanical and Aerospace Engineering Theses - Archive

While dealing with problems of impact analysis, where the force is dependent on the time, one can use the transient analysis to compute the response. Transient wave propagation has drawn interest from a long time mainly because of the way structural members behave when subjected to high rates of loading. Solutions to these problems find applications in the design of various mechanical equipments, or any situation where rigid objects are impacting on structural members.The first part of this study deals with the axial wave propagation in cones of different apex angles using transient analysis in ANSYS. The results from the …

Fiber-Optic Pressure Sensor For Time-Of-Flight Measurements In A Shock Wave, Karthikeyan Jagadevan

Mechanical and Aerospace Engineering Theses - Archive

Fiber-optic sensors are widely employed to detect pressures and temperatures precisely. In particular, MEMS-based Ber-optic sensors are immune to electromagnetic interference but may have limitations at high temperatures as encountered in combustors. To ensure high-temperature survivability, such sensors may be bondedanodically. This project explains the development of a Ber-optic pressure sensor utilizing intensity based principle whereby a fused silica optical window was glued to the tungsten carbide enclosure. The development was estimated to determine high pressures of up to at least 3.5 MPa (507 psi). The sensor is designed to capture the pressure pulse and the time-of-flight (TOF) of a …

Peak Stress Of Composite Multiple-Hole Laminates With And Without Patch, Sakthivel Selvaraj

Mechanical and Aerospace Engineering Theses - Archive

In repairing of composite structures, the damage in the composite laminate is usually removed in the form of circular cutouts which results in holes in the laminate. Then a patch laminate is adhesively bonded to the damaged composite laminate. The presence of holes in any structures creates a high stress concentration at the edge of the hole which indeed reduces the life of the structure. The primary objective of this study is to investigate the high stress of the damaged laminate with different hole patterns and the effect of having single and double patches with various configurations on these hole …

Computational Model For Transient And Steady State Analysis Of A 1-Dimensional Auto-Thermal Reformer, Srikanth Honavara Prasad

Mechanical and Aerospace Engineering Theses - Archive

This study presents a 1-dimensional mathematical model of steam reformer to be used with high temperature solid oxide fuel cell (SOFC). Steam reforming (SR) is widely used in industries to produce hydrogen from hydrocarbons. There are various physical processes associated with chemical reactions in the SR of methane such as mass, heat and momentum transport. In this study a one-dimensional SR reactor with built-in preheater and mixing chamber connected to fuel gas and steam reservoirs is modeled and analyzed. The main part of the reformer is a metallic tube with catalyst coating on the inner walls, and it can be …

Parameter Estimation In Heat Transfer And Elasticity Using Trained Pod-Rbf Network Inverse Methods, Craig Rogers

Electronic Theses and Dissertations

In applied mechanics it is always necessary to understand the fundamental properties of a system in order to generate an accurate numerical model or to predict future operating conditions. These fundamental properties include, but are not limited to, the material parameters of a specimen, the boundary conditions inside of a system, or essential dimensional characteristics that define the system or body. However in certain instances there may be little to no knowledge about the systems conditions or properties; as a result the problem cannot be modeled accurately using standard numerical methods. Consequently, it is critical to define an approach that …

Experimental Studies Of The Heat Transfer Characteristics Of Silica Nanoparticle Water-Based Dispersion In Pool Boiling Using Nichrome Flat Ribbons And Wires, Diane Marie Vazquez

Electronic Theses and Dissertations

This work deals with a study of enhanced critical heat flux (CHF) and burnout heat flux (BHF) in pool boiling of water with suspended silica nanoparticles using ribbon-type and wire heaters. Previously our group and other researchers have reported three-digit percentage increase in critical heat flux in silica nanofluids. This study investigates the effect of various heater surface dimensions and cross-sectional shapes on pool boiling heat transfer characteristics of water and water-based nanofluids. CHF and BHF were analyzed for circular and rectangular cross-section nichrome wires and ribbons of increasing sizes in the range of 0.32mm to 2.38mm width, approaching a …

High Heat Flux Spray Cooling With Ammonia On Enhanced Surfaces, Huseyin Bostanci

Electronic Theses and Dissertations

Many critical applications today, in electronics, optics and aerospace fields, among others, demand advanced thermal management solutions for the acquisition of high heat loads they generate in order to operate reliably and efficiently. Current competing technologies for this challenging task include several single and two phase cooling options. When these cooling schemes are compared based on the high heat flux removal (100-1000 W/cm2) and isothermal operation (within several oC across the cooled device) aspects, as well as system mass, volume and power consumption, spray cooling appears to be the best choice. The current study focused on high heat flux spray …

A Model Integrated Meshless Solver (Mims) For Fluid Flow And Heat Transfer, Salvadore Gerace

Electronic Theses and Dissertations

Numerical methods for solving partial differential equations are commonplace in the engineering community and their popularity can be attributed to the rapid performance improvement of modern workstations and desktop computers. The ubiquity of computer technology has allowed all areas of engineering to have access to detailed thermal, stress, and fluid flow analysis packages capable of performing complex studies of current and future designs. The rapid pace of computer development, however, has begun to outstrip efforts to reduce analysis overhead. As such, most commercially available software packages are now limited by the human effort required to prepare, develop, and initialize the …

Processing, Optimization And Characterization Of Fire Retardant Polymer Nanocomposites, Jinfeng Zhuge

Electronic Theses and Dissertations

Fiber reinforced polymeric composites (FRPC) have superior physical and mechanical properties, such as high specific strength, light weight, and good fatigue and corrosion resistance. They have become competitive engineering materials to replace conventional metallic materials in many important sectors of industry such as aircraft, naval constructions, ships, buildings, transportation, electrical and electronics components, and offshore structures. However, since FRPC contain polymer matrix, the polymer composites and their structures are combustible. FRPC will degrade, decompose, and sometimes yield toxic gases at high temperature or subject to fire conditions. The objective of this study is to design and optimize fire retardant nanopaper …

Alternative Cooling Technologies For Telecommunication Data Centers: Air Cooling And Rear Door Heat Exchangers, Venkata Naga Poornima Mynampati

Mechanical and Aerospace Engineering Theses - Archive

Telecommunication industry is currently emphasizing to a miniaturization and convergence. The need for smaller, smarter and faster devices is leading drastic increment in power density and accordingly, thermal management of such devices has become a challenge. The heat generated by the devices has to be dissipated in order to ensure proper and efficient functioning of the electronics. Electronics cooling ranges from device level to the room level cooling. Data Center is a facility (room) consisting of servers used for managing and transferring data or information. The thermal management of this facility is challenging due to the huge decrease in floor …

Macroinstability And Perturbation In Turbulent Stirred Tank Flows, Somnath Roy

LSU Doctoral Dissertations

Impeller stirred tank reactors (STRs) are commonly used in the chemical processing industries for a variety of mixing and blending technologies. In this research, a numerical study of flow and mixing inside turbulently agitated STRs are carried out. An immersed boundary method (IBM) is utilized to represent moving impeller geometries in the background of multi-block structured curvilinear fluid. The IBM This curvilinear-IBM methodology is further combined with the large eddy simulation (LES) technique to address the issue of modeling unsteady turbulent flows in the STR. Verification of the combined IBM-LES implementation strategy in curvilinear coordinates is done through comparisons with …

Uncertainty Analysis And Instrument Selection Using A Web-Based Virtual Experiment, Praveen Malali, Pooja Bais, Robert Choate, Sushil Chaturvedi

Mechanical & Aerospace Engineering Faculty Publications

A methodology has been developed and successfully implemented for transforming physical experiments in an undergraduate thermo-fluids laboratory at Old Dominion University (ODU), a doctoral university, into web-based virtual experiments while the Mechanical Engineering (ME) faculty at Western Kentucky University (WKU), an undergraduate university, have developed and implemented a Design of Experiments (DOE) Plan to assure that graduates of their program have acquired the skills necessary to design and conduct experiments and analyze experimental results. This paper presents details about a web-based virtual experiment designed to teach students about selection of instruments based on the uncertainty estimated from the virtual experiment. …

Formula Sae Impact Attenuator Testing, Chad Abrahamson, Bill Bruns, Joseph Hammond, Josh Lutter

The Journal of Undergraduate Research

The purpose of this paper is to validate the impact attenuator designed by SDSU Formula SAE team according to 2010 Formula SAE rules. The impact attenuator is made of Plascore PCGA-XR1-5.2-1/4-P-3003 aluminum honeycomb that is pre-crushed to 245 psi. The test was dynamically performed using a 661 lb mass dropped 8.3 ft onto the material sample at 23 ft/sec, and data was measured with an Olympus i-SPEED 3 high speed camera. The impact attenuator must have an average deceleration equal to or less than 20 G’s and a peak deceleration equal to or less than 40 G’s. Two specimens were …

Measurement Sensitivity In Tapping-Mode Atomic Force Microscopy Using A Bi-Harmonic Drive Signal, Santosh R. Kodandarama, Douglas A. Bristow

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In tapping mode atomic force microscopy, surface features are measured indirectly via the amplitude of the tapping cantilever. a change in surface profile is detectable only if it results in an amplitude change that is significant enough to be measured by the optics. Previous works have focused on improving sensitivity through the system's Q-factor, either by changing physical cantilever properties or using feedback control, but those approaches undesirably slow down the dynamic response. in this work we take a novel approach to sensitivity amplification by reshaping the tapping trajectory. by shaping the trajectory so that the probe spends a greater …

A Comparison Of Hemodynamic Performance In Mehcanical And Biological Heart Valve Prostheses, Philip Mathew

Masters Theses and Doctoral Dissertations

Heart valve prostheses are used to replace heart valves in patients afflicted with valvular heart disease. The malfunctioning heart valve adversely affects the fluid mechanical performance. While the choice of mechanical VS biological valve prostheses is dependent on the patient, the biological valves should have improved hemodynamic performance compared to the mechanical valves. This work focused on CFD analysis of the Starr-Edwards caged ball valve and a biological valve and serves to validate the improved hemodynamics of the latter valve in comparison to the former. Commercial CFD software (CFD-GEOM, CFD-ACE, CFD-VIEW) are used for the analys is. The main results …

An Investigation On Pulsing Performance Of Mn Class Bi-Propellant Thrusters, Carlos Francisco Gomez

Open Access Theses & Dissertations

With the advancement of technology and machining methods, considerable attention has been focused in manufacturing micro thrusters for micro spacecraft applications (Yetter et al, 2003). Micro propulsion systems are currently being investigated for Miniature Kill Vehicles (MKV) and Micro Satellite Systems (MSS) with an emphasis in reducing weight and cost but without affecting performance. Reducing the weight seems practical when reducing the size of the propulsion system, but problems are encountered with system design.

In addition, propulsion requirements strongly influence choice in propellant and complexity. A thorough understanding of stabilizing thrust levels and the ability to control the propulsion system …

Simulation Algorithm And Validation Of A Photovoltaic Water Pumping System, I. Odeh, Y. Yohannis, Brian Norton

Articles

A photovoltaic (PV) water pumping system has been modelled using TRNSYS considering a power supply, a direct current (DC)/alternating current (AC) inverter, an AC induction motor, a centrifugal pump, a well, a water storage tank, and an overflow protection device. The model emulates actual pumping head curves, uses numerical methods to determine pump system working points, and includes a storage tank as a component in the system. It simulates PV-powered water pumping systems, constant voltage tracking, voltage frequency modulation, and maximum power point tracking algorithms; variable inverter frequency with variable motor efficiency, variable inverter frequency with constant motor efficiency, and …

Multi-Objective Optimization Of Mechanical Elements Using Artificial Bee Colony Optimization Technique, Vimal J. Savsani, R V. Rao, D P. Vakharia

Early Career Technical Journal (ECTJ)

Proceedings of the ASME Early Career Technical Conference, October 1-2, 2010. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia

pp. 146-152