Mechanical Engineering Commons^™

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, …

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 …

Combustion Characteristics Of Alh3 Flame, Sudipa Sarker

Open Access Theses & Dissertations

The combustion characteristics of Al hydride and Al were compared using a combustion chamber. Burning rate, ignition energy and temperature at atmospheric temperature and pressure in carbon dioxide and O2 were tested with a volumetric flow rate that ranged from 10 to 50% in Ar. A spark ignition system was used to ignite the Alane and Aluminum. The combustion rate was measured using a high speed camera. Results showed the combustion rate of Alane and Aluminum decreases with increasing volumetric flow rate of oxidizer. And the combustion rate of Alane is higher than that of Aluminum. Alane needs more ignition …

Scaffold Based In-Vitro Osteodistraction For Bone Tissue Engineering, Cesar Adrian Terrazas

Open Access Theses & Dissertations

Engineering of hard tissues such as bone is a challenge because of the limited ability of the body to heal large defects. Current treatment options, such as employing bone sections from the patient or a deceased donor have been utilized for some time now with various degrees of success. However, these methods still exhibit many limitations such as limited supply and the possibility of transmission of disease.

To address the many limitations of bone grafts, synthetic engineered substitutes have been developed and widely researched for nearly three decades. Generally termed scaffolds, these are matrices that serve the purpose of temporary …

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 …

An Integration Of A Modern Flight Control System Design Technique Into A Conceptual Design Stability And Controls Tool, Aeromech, Amen Omoragbon

Mechanical and Aerospace Engineering Theses - Archive

The aircraft conceptual design (CD) phase is the most abstract, thus challenging phase of the entire aircraft design process. It is the responsibility of the CD engineer to identify and then to explore various aircraft concepts with the goal of arriving at the most promising concept for further evaluation. During this early design phase, the discipline stability and control tends to be underrepresented due to the lack of non-linear aerodynamic and inertia data. The methodology and software AeroMech is a vehicle configuration independent aircraft conceptual design stability and control tool, developed to help the conceptual designer to address stability and …

An Analytical Model For Rotator Cuff Repairs, A. Aurora, Jorge E. Gatica, Antonie J. Van Den Bogert, J. A. Mccarron, Kathleen A. Derwin

Mechanical Engineering Faculty Publications

Background

Currently, natural and synthetic scaffolds are being explored as augmentation devices for rotator cuff repair. When used in this manner, these devices are believed to offer some degree of load sharing; however, no studies have quantified this effect. Furthermore, the manner in which loads on an augmented rotator cuff repair are distributed among the various components of the repair is not known, nor is the relative biomechanical importance of each component. The objectives of this study are to (1) develop quasi-static analytical models of simplified rotator cuff repairs, (2) validate the models, and (3) predict the degree of load …

Numerical Investigation Of Mechanical Durability In Polymer Electrolyte Membrane Fuel Cells, Ahmet Kusoglu, Michael H. Santare, Anette M. Karlsson, Simon Cleghorn, William B. Johnson

Mechanical Engineering Faculty Publications

The relationship between the mechanical behavior and water transport in the membrane electrode assembly (MEA) is numerically investigated. Swelling plays a key role in the mechanical response of the MEA during fuel cell operation because swelling can be directly linked to the development of stresses. Thus, in the model introduced here, the stresses and the water distribution are coupled. Two membranes are studied: unreinforced perfluorosulfonic acid (PFSA) and an experimental reinforced composite membrane. The results suggest that open-circuit voltage operations lead to a uniform distribution of stresses and plastic deformation, whereas under current-load operation, the stresses and the plastic deformation …

Imbalance Response Of A Four Degree Of Freedom Rigid Rotor Supported By Hybrid Three Pad Air Foil Bearing, Prajwal Krishna Shetty

Mechanical and Aerospace Engineering Theses - Archive

Air foil bearings (AFB's) are widely used in small to midsized turbomachinery. They provide safer, cleaner and cheaper bearing operation. They are simple in construction, offer very low drag friction and have very high reliability at high speed operations. A major advantage of air foil bearings compared to conventional rigid surface bearings is their superior dynamic performance in rotor bearing systems. Since there is no contact between the rotor and bearing surface, the air foil bearings have a higher service life compared to rigid surface bearings. Hybrid AFB's operate under both hydrodynamic and hydrostatic condition. The present study is a …

Dual Axis Solar Tracker, Weston Sapia, Jason Birnie

Electrical Engineering

No abstract provided.

Nitrous Oxide Cooling In Hybrid Rocket Nozzles, Patrick Lemieux

Mechanical Engineering

The Department of Mechanical Engineering at the California Polytechnic State University, San Luis Obispo, has developed an innovative program of experimental research and development on hybrid rocket motors (where the fuel and the oxidizer are in different phases prior to combustion). One project currently underway involves the development of aerospike nozzles for such motors. These nozzles, however, are even more susceptible to throat ablation than regular converging diverging nozzles, due the nature of their flow expansion mechanism. This paper presents the result of a recent development project focused on reducing throat ablation in hybrid rocket motor nozzles. Although the method …

Experimental And Cfd Investigations Of Lifted Tribrachial Flames, Zhiliang Li

Electronic Theses and Dissertations

Experimental measurements of the lift-off velocity and lift-off height, and numerical simulations were conducted on the liftoff and stabilization phenomena of laminar jet diffusion flames of inert-diluted C3H8 and CH4 fuels. Both non-reacting and reacting jets were investigated, including effects of multi-component diffusivities and heat release (buoyancy and gas expansion). The role of Schmidt number for non-reacting jets was investigated, with no conclusive Schmidt number criterion for liftoff previously known in similarity solutions. The cold-flow simulation for He-diluted CH4 fuel does not predict flame liftoff; however, adding heat release reaction leads to the prediction of liftoff, which is consistent with …

Experimental Studies Of Liquefaction And Densification Of Liquid Oxygen, Jonathan Koert Partridge

Electronic Theses and Dissertations

Rocketry employs cryogenic refrigeration to increase the density of propellants, such as oxygen, and stores the propellant as a liquid. In addition to propellant liquefaction, cryogenic refrigeration can also conserve propellant and provide propellant subcooling and densification. Previous studies analyzed vapor conditioning of a cryogenic propellant, which occurred by either a heat exchanger positioned in the vapor or by using the vapor as the working fluid in a refrigeration cycle. This study analyzes the refrigeration effects of a heat exchanger located beneath the vapor-liquid interface of liquid oxygen. This study predicts the mass liquefaction rate and heat transfer coefficient for …

Stress Concentration Factors For V-Notched Plates Under Axisymmetric Pressure, Nathan J. Mutter

HIM 1990-2015

The topic of this thesis is the investigation of the local states of stress resulting from the introduction of av-notch in a coaxial circle on the pressurized surface of a circumferentially clamped plate subject to axisymmetric loading. The understanding of the fracture behavior of a component experiencing such a condition is of particular interest to the aerospace and defense industries where circular plate components are often utilized. In such applications, it is imperative that the designer be able to predict the loading conditions facilitating dynamic fracture. As a step towards solving such problems, the quasi-static analogy is studied. Specifically, the …

Combustion Dynamics And Fluid Mechanics In Acoustically Perturbed Non-Premixed Swirl-Stabilized Flames., Uyi Idahosa

Electronic Theses and Dissertations

The prevalence of gas turbines operating in primarily lean premixed modes is predicated on the need for lower emissions and increased efficiency. An enhancement in the mixing process through the introduction of swirl in the combustion reactants is also necessary for flame stabilization. The resulting lean swirling flames are often characterized by a susceptibility to feedback between velocity, pressure and heat release perturbations with a potential for unstable self-amplifying dynamics. The existing literature on combustion dynamics is predominantly dedicated to premixed flame configurations motivated by power generation and propulsive gas turbine applications. In the present research effort, an investigation into …

Experimental Analysis On The Effects Of Superficial Liquid And Gas Velocities In The Removal Of Hydrogen Sulfide From A Brine/Oil Mixture, Joshua Lee

Electronic Theses and Dissertations

Hydrogen Sulfide (H2S) is a harmful gas produced during petroleum extraction that leads to corrosion of drilling tools and pipelines. However, a H2S-scavenging liquid compound, when added to pipelines, interacts with liquids that absorbed H2S to create a non-corrosive bi-product. The interaction is associated with the mixing of gases and liquids. This thesis is a study on the effect of superficial gas and liquid velocities on the scavenger's efficiency. This study employs two experimental setups designed to simulate the mixing of gases and liquids within pipelines. A high pressure closed loop was designed and fabricated to determine the influence of …

Numerical Modeling Of The Shock Tube Flow Fields Before Andduring Ignition Delay Time Experiments At Practical Conditions, Mouna Lamnaouer

Electronic Theses and Dissertations

An axi-symmetric shock-tube model has been developed to simulate the shock-wave propagation and reflection in both non-reactive and reactive flows. Simulations were performed for the full shock-tube geometry of the high-pressure shock tube facility at Texas A&M University. Computations were carried out in the CFD solver FLUENT based on the finite volume approach and the AUSM+ flux differencing scheme. Adaptive mesh refinement (AMR) algorithm was applied to the time-dependent flow fields to accurately capture and resolve the shock and contact discontinuities as well as the very fine scales associated with the viscous and reactive effects. A conjugate heat transfer model …

Nebraska Summary: S776 Massey Ferguson 7475, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Nebraska Summary: S775 Massey Ferguson 7465, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 1980: Kubota M135x, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 1977: Massey Ferguson 2670hd, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 1971: John Deere 8320rt, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Test 1970: John Deere 8295rt, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

Phase Investigation Of Zirconia Fibers And Their Applications On Solid Oxide Fuel Cells (Sofcs), Luping Li

LSU Master's Theses

Pure zirconia nanofibers were fabricated by electrospinning zirconia-polymer precursor and subsequent annealing. Fiber properties such as polymer decomposition, crystallization formation, phase transformation, surface morphologies, etc., were investigated by various techniques, including thermogravimetric analysis (TGA) and differential thermal analysis (DTA), high temperature differential scanning calorimeter (HTDSC), powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), etc. It was found the crystallization of as-spun fibers started at 450 °C and the initial crystallized zirconia phase was tetragonal (t), which began transforming to monoclinic (m) phase at 650 °C as evidenced by XRD; HTDSC showed at different thermal circles, the m-to-t transformation …

Degradation Behavior Of Shape Memory Polymer Due To Water And Diesel Fuel, Mohammad Nazmul Hasan Nahid

LSU Master's Theses

Shape memory polymers (SMP) are smart materials, which have the ability to memorize the original or permanent shape. Owing to this characteristic SMP can be used as a sensor, a transplant, as well as structural materials in wide range of applications. Despite its importance, its degradation behavior is still not completely known; and only a limited amount of work has been reported in the literature. In this thesis, the experiments have been carried out to evaluate the degradation behavior of Veriflex- SMP (industry supplied SMP samples) upon exposure to two different types of liquids; water and diesel fuel separately. It …

Characterization Of Composite Piezoelectric Materials For Smart Joint Applications, Hari Prasad Konka

LSU Master's Theses

Piezoelectric materials have the ability to provide desired transformation from mechanical to electrical energy and vice versa. When a mechanical force is applied to the piezoelectric material an electrical voltage is generated and when an electrical voltage is applied to the piezoelectric material it gets strained or deformed. Owing to these characteristics piezoelectric materials can be used as a sensor, an actuator, as well as a power generation unit. The high brittleness property of the original piezoelectric material is one of the major constraints in using them in the engineering applications. In order to overcome this disadvantage the composite piezoelectric …

Design And Fabrication Of Micronozzles For Drug Delivery Applications, Yuxuan Zhou

LSU Master's Theses

Inhaled drug is an important drug delivery route. It is widely used in medications for respiratory disorders. However, it has some significant limitations, for examples, concentration of drug, output, and particles size, are not accurately controlled in most of the available drug delivery systems today. Various new devices and technologies continue to be developed and introduced. Vibrating orifice is one of them. The critical issue of vibrating orifice technology is the fabrication of micro-nozzles. Traditional technique to fabricate these nozzles is to use dry etching method, which tends to be expensive and inconvenient for mass production. Other two optional fabrication …

A Portable Phonatory Feedback Device For Patients With Speech Disorders, Richie Sajan

LSU Master's Theses

Vocal intensity-related speech disorders such as dysarthria and vocal nodules can limit quality of life and reduce the patient’s ability to interact with family, socialize, or pursue employment. Behavioral speech therapies exist to address these issues but have limited effectiveness because they are expensive and clinic-based. The ability to monitor vocal intensity outside of the clinical setting will greatly aid in the treatment of these speech disorders, enabling patients to make quicker progress by reinforcing techniques learned in the clinic. The Voice Volume Monitor (VVM) is a portable and cost-effective therapeutic aid designed for this purpose, providing real-time feedback regarding …

Computational Examination Of Compaction Wave-Boundary Interaction In Granular Explosive, Anirban Mandal

LSU Master's Theses

Interactions between initially planar, piston supported compaction waves in heterogeneous energetic solids and macro-scale rigid boundaries were computationally examined for a wide range of piston impact speeds (20 ≤ U_p ≤ 500 m/s) and initial solid volume fractions of the material (0.73 ≤ ϕ₀ ≤ 0.90). The response of the material was described by a continuum theory that accounts for both elastic and inelastic compaction in a thermodynamically consistent manner. Initial conditions were imposed by interpolating the spatial structure of one-dimensional steady compaction waves onto two-dimensional domains considered in this study. For a planar wedge boundary, the peak …

Enhancement Of Single-Lap Joint Strength Under Tension Using Piezoelectric Actuation, Ryan Michael Meyer

LSU Master's Theses

Composite adhesively bonded joint structures have seen increased use over conventional riveted due to their ease of manufacturing and quality strength-to-weight ratios. However, adhesively bonded joints lack the rigidity and failure strength of riveted assemblies, due to high stress concentrations which develop in the adhesive layer, which makes them prone to undesirable deformation and failure. Piezoelectric materials feature the ability to produce mechanical strain when subjected to an applied voltage and vice-versa. Therefore, it is proposed to use piezoelectric actuators to transmit counterbalancing forces to increase the rigidity and strength of composite joints. Existing studies have been limited in that …