Mechanical Engineering Commons^™

A Low Cost Micro Scale Cyclone Seperator- Design And Computational Fluid Dynamics Analysis, Deval Pandya

Mechanical and Aerospace Engineering Theses - Archive

Microparticle separation process has a variety of application varying from application in biological and biomedical industries for analysis and diagnosis, in biogas manufacturing to separate phases as well as in defense sector for detection of biological weapons like anthrax. Available electrical, magnetic, acoustic and various other methods are either very costly or not portable. The proposed design of micro scale cyclone separator is low cost as well as portable and easy to manufacture. Huge cyclone separators are widely used in various industries since decades but due to lack of research in micro scale cyclones no direct and sufficient data is …

Effect Of Friction On The Zel'dovich Von Neumann Doring To Chapman Jouguet Transition, Sushma Rao

Mechanical and Aerospace Engineering Theses - Archive

Detonation theory proposes Chapman-Jouguet state of equilibrium due to the sonic speed of the products relative to the wave. Experimental observations however indicated the existence of a sub-Chapman-Jouguet state. The dissertation proposes that friction plays a role in defining such a sub-optimal state in detonation wave propagation in ducts. The problem is addressed analytically by decoupling the friction losses from the chemical reactions. The non-equilibrium conditions associated with detonation is modeled by detailed chemistry.

Multi Objective Thermal And Energy Based Design Optimization Of Telecommunication Cabinets/Shelters, Bharathkrishnan Muralidharan

Mechanical and Aerospace Engineering Theses - Archive

The miniaturization and convergence of the consumer electronic products such as cell phones and digital cameras has necessitated an increase in the number of transistors on a die, board and systems. This has resulted in a requirement for a more robust thermal management of such electronics to increase the reliability of the system. Access networks provide the last mile of connectivity for the telecommunication network users. In the access network, the outside plant telecommunication cabinets houses electronic components and switching devices. These cabinets are standalone outdoor enclosures, and many a times they are located in hostile environments. With the current …

Experimental Study Of Micro-Vortex Generators At Mach 2.5, Adam J. Pierce

Mechanical and Aerospace Engineering Theses - Archive

Vortex generators are geometrical shapes that produce trailing vortices and are widely used for their ability to improve the flow quality over areas where flow separation may occur. Current topics involve utilizing the performance capabilities of vortex generators to influence the boundary layer under supersonic conditions. Such influence may provide an alternative means of reducing boundary layer flow separation and improving the overall quality of the flow in the boundary layer. This influence would maintain low drag in supersonic inlets and reduce the need for mechanical equipment used for boundary layer bleed leading to a reduction in aircraft weight and …

Experimental Investigation Of Thermal Behaviour Of Air Foil Bearings, Ramesh Pandeshwara Sadashiva

Mechanical and Aerospace Engineering Theses - Archive

Micro-turbo machinery demands gas bearings to ensure compactness, lightweight and extreme temperature operation. Gas bearings with large stiffness and damping, and preferably of low cost, will enable successful commercial applications. One of the gas bearing which is used for experimental investigation is the Air foil bearing. Previously developed test rig has been modified and further developed for investigating this bearing at various temperatures and speeds. These gas bearings are self acting hydrodynamic air bearings which have been successfully applied to a variety of turbo machinery applications. This new modified test rig also has the capability to measure bearing torque during …

Analysis And Design Of A Two-Wheeled Robot With Multiple User Interface Inputs And Vision Feedback Control, Eric Stephen Olson

Mechanical and Aerospace Engineering Theses - Archive

This thesis describes the development of a small, inexpensive, controllable mobile two-wheeled robot. It also describes the development of a software interface which allows several open- and closed-loop control methods to be easily implemented. The developed hardware and software modules provide for an open and modular system for research purposes. This is demonstrated through the Bluetooth wireless control of the robot using LabVIEW based software modules. The open-loop control inputs implemented are sliders in a LabVIEW GUI, joystick, and voice commands. The closed-loop control methods included a PD control algorithm that guides the robot to go directly to a user …

Applications Of Sensitivity Data To Eigensolution Reanalysis Of Modified Structures, Chandrashekhar Sureshchandra Patadia

Mechanical and Aerospace Engineering Theses - Archive

Methods of computing eigensolution sensitivity have been known for a long time. Both exact and approximate methods are available in the literature. While eigenvalue sensitivity is used routinely in structural optimization with eigenvalue constraints, few application of eigenvector derivatives are reported in the literature. The objective of this thesis is to present an effective eigensolution reanalysis approach using first and second order eigenvector sensitivity data. In the proposed new approach, modes shapes and their derivatives are used as basis vector for eigensolution of the modified system. Comparison of numerical results with several existing eigensolution reanalysis methods shows the proposed algorithms …

Inverse Design Of Airfoils Using A Flexible Membrane Method, Kamon Thinsurat

Mechanical and Aerospace Engineering Theses - Archive

The Modified Garabedian Mc-Fadden (MGM) method is used to inversely design airfoils. The Finite Difference Method (FDM) for Non-Uniform Grids was developed to discretize the MGM equation for numerical solving. The Finite Difference Method (FDM) for Non-Uniform Grids has the advantage of being used flexibly with an unstructured grids airfoil. The commercial software FLUENT is being used as the flow solver. Several conditions are set in FLUENT such as subsonic inviscid flow, subsonic viscous flow, transonic inviscid flow, and transonic viscous flow to test the inverse design code for each condition. A moving grid program is used to create a …

Effective Thermal Management Of Electronic Devices From System To Die Level, Saket Karajgikar

Mechanical and Aerospace Engineering Dissertations - Archive

In any electronic device, the resistance to the flow of current through the transistors, interconnects, etc. results in a significant heat generation. If this heat is not removed from the device by providing appropriate cooling solutions, the possibility of thermal run away is very high. Under this condition the temperature would continue to rise until it reaches a point at which the device ceases to operate or loses its physical integrity. In presence of a cooling mechanism, the temperature rise is moderated as it asymptotically reaches an acceptable steady state value. Before any device is introduced in the market, it …

Trajectory Uncertainty Analysis For The Development Of A Queuing Model For The National Airspace System, Manju Nag

Mechanical and Aerospace Engineering Theses - Archive

In this research, we propose to support the development of a queuing model for the National Airspace System (NAS) by providing distributions for the various phases of flight, accounting for the uncertainties in flight trajectory which includes factors such as weight, power factor, lift co-efficient. In addition to this, a detailed study is done on the impact of weather on flight routes and two days in 2006 are compared to show the effect of weather on flight times. The research develops from a good understanding of the NAS and its requirements to implement a system capable of dealing with issues …

Aerodynamic Shape Optimization Of A Vertical Axis Wind Turbine, Travis Justin Carrigan

Mechanical and Aerospace Engineering Theses - Archive

The purpose of this study is to introduce and demonstrate a fully automated process for optimizing the airfoil cross-section of a vertical axis wind turbine (VAWT). The objective is to maximize the torque while enforcing typical wind turbine design constraints such as tip speed ratio, solidity, and blade profile. By fixing the tip speed ratio and solidity of the wind turbine, there exists an airfoil cross-section for which the torque can be maximized, requiring the development of an iterative design system.The design system required to maximize torque incorporates rapid geometry generation and automated hybrid mesh generation tools with viscous, unsteady …

Effect Of Structural Design Parameters On Wafer Level Csp Ball Shear Strength And Their Influence On Accelerated Thermal Cycling Reliability, Nikhil R. Lakhkar

Mechanical and Aerospace Engineering Dissertations - Archive

Wafer level chip scale package (WLCSP) is one of the most popular packages due to its size and cost advantages. It is expected that the usage of WLCSP in microelectronics and MEMS industry combined is going to cross 16000 Million Units by 2013. One of the main advantages of implementing WLCSP is its time to market because most of the package is done at the wafer level. Once the wafer processing is completed the package is just diced and mounted on board and the board is ready to go. However, just like any other package WLCSP too is not ideal …

Solution To Incompressible Navier Stokes Equations By Using Finite Element Method, Wanchai Jiajan

Mechanical and Aerospace Engineering Theses - Archive

The finite element method has become a popular method for the solution of the incompressible Navier-Stokes equations. High Reynolds number cases require fine meshes so computational efficiency becomes an important factor in algorithm and code development. In this work, a Galerkin finite element method is proposed to solve the two dimensional incompressible Navier-Stokes equations. This approach typically leads to a sparse and indefinite matrix that is difficult to solve efficiently. The formation of an indefinite matrix is avoided in the present work by introducing an artificial compressibility term in the continuity equation. The concept of this method is to transform …

Finite Element Analysis Of Stresses In Involute Spur & Helical Gear, Shreyash D. Patel

Mechanical and Aerospace Engineering Theses - Archive

Developing an analytical approach and modeling procedure to evaluate stress distribution under velocity and moment would provide a useful tool to improve spur gear design with high efficiency & low cost. The purpose of this work is to analyze and validate the stress distribution in spur & helical gears using contemporary commercial FEM program ANSYS coupled with the Pro/E solid modeler. Gear profiles are created in Pro Engineer using the Relation and Equation modeling procedure so as to make it a general model, dependant on certain key features like number of teeth, diametral pitch, and pressure and helix angle. These …

Effects Of Curvature On The Stresses Of A Curved Laminated Beams Subjected To Bending, Thien Nguyen

Mechanical and Aerospace Engineering Theses - Archive

In aircraft structural applications, curved laminated beam structures are often used as part of the internal structure. If the curved composite structure is subjected to bending that tends to flatten or compress the composite structure, interlaminar stresses can be generated in the thickness direction of the composites. These interlaminar stresses are the major factor of delamination failure. Besides these stresses, the in-plane stresses can be also affected by the pre-existence of the beam curvature. This research has studied the variation of both tangential and radial stresses with respect to the changing in curvature, stacking sequence, and fiber orientation in a …

A Micromechanics Model Of Thermal Expansion Coefficient In Fiber Reinforced Composites, Nittapon Srisuk

Mechanical and Aerospace Engineering Theses - Archive

Fiber reinforced composites are widely used for the various applications in the aerospace, automotive, infrastructures and sporting goods industries. The evaluations of its mechanical and thermal properties are needed for accurate estimation of their structural response. In this study, a mathematical closed-form expression of unit cell model was developed to estimate the coefficient of thermal expansion (CTE) along longitudinal and transverse directions of unidirectional lamina. Unlike the previous models, the present model takes into consideration of the fiber configuration and volume fraction of each constituent in the unit cell. In addition, the model is also able to obtain the stresses …

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 …

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 …

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 …

Guidance And Control For Chase Uav Via Sliding Mode Approach, Takeshi Yamasaki, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This study focuses on integrated guidance and control for a chasing UAV against a maneuvering target. a sliding mode approach is selected to develop the integrated guidance and control using a full model of nonlinear, rigid body, 6 Degree-Of-Freedom equations of motion including nonlinear aerodynamics for the target-following capability and maneuverability enhancement against uncertain target maneuvers. Intermediate control variables for the integrated guidance and control system are carefully selected and approximated time derivatives of a sliding surface are applied such that a sliding surface structure is simple and sufficient to propagate the actuator input to the sliding surface in order …

Analysis Of Wake Vortices Of A Medium Range Twin-Propeller Military Cargo Aircraft Using Statistically Designed Experiments, Burhan Sahin

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental study was initiated to analyze the trajectories of the streamwise vortices behind the wing tip and flap of a medium range and propeller driven twin-engine military cargo aircraft. The model used for the experimental study was a generic, high wing and half model of a propeller driven aircraft and mounted within Old Dominion University's Low Speed Wind Tunnel where the wind tunnel flow speed was set to constant value of 9 m/sec. The main purpose of the study was to reach regression models for the motion and vorticity strength of both vortices under varying factors such as angle …

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 …

Direct Detection Of No Produced By High-Temperature Surface-Catalyzed Atom Recombination, Dušan A. Pejaković, Jochen Marschall, Lian Duan, Maria P. Martin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The surface-catalytic recombination of oxygen and nitrogen atoms to form nitric oxide was confirmed by the direct detection of product NO molecules, using single-photon laser-induced fluorescence spectroscopy. Experiments were performed from room temperature to 1200 K in a quartz diffusion-tube sidearm reactor enclosed in a high temperature tube furnace. Atomic nitrogen was generated using a microwave discharge, and atomic oxygen was produced via the rapid gas-phase titration reaction N + NO → O + N2. The use of isotopically labeled titration gases 15N16O and 15N18O allowed for the unambiguous identification of nitric oxide produced by the O + N surface …

Direct Numerical Simulation Of Hypersonic Turbulent Boundary Layers With Varying Freestream Mach Number, L. (Lian) Duan, I. Beekman, M. P. Mart́In

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, the effects of freestream Mach number on the statistics and large-scale structures in compressible turbulent boundary layers are investigated using direct numerical simulations (DNS). DNS of turbulent boundary layers with nominal freestream Mach number ranging from 3 to 8 are performed. The validity of Morkovin's scaling, strong Reynolds analogy, and Walz's equation are assessed. We find that many of the scaling relations used to express compressible boundary layer statistics in terms of incompressible boundary layers still hold for the range of freestream Mach number considered. Compressibility effects are enhanced with increasing freestream Mach number but remain insignificant, …

Development Of An Optical Fiber-Based Corrosion Detection Sensor Based On Laser Light Reflection, Manjunatha Shenoy

Mechanical and Aerospace Engineering Theses - Archive

Corrosion plays a detrimental effect on the structural integrity of many engineering structures. It can compromise the safe operation of these structures by forming corrosion pits that deteriorates the structural surfaces and causes stress concentrations. Therefore, it is critical that corrosions are detected before structural integrity is compromised and repair becomes economically prohibitive. However, corrosions usually occur at intricate places that are hard to inspect visually. Manual inspection of the structures for corrosions requires dismantling the structures, which incurs high maintenance costs and could potentially cause damage to the components. One approach to reduce this cost is to detect and …