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Articles 1 - 9 of 9

Full-Text Articles in Mechanical Engineering

An Investigation Of The Frictional And Thermal Behavior Of Oscillatory Sliding Line Contacts, Mongi Mansouri Jan 2007

An Investigation Of The Frictional And Thermal Behavior Of Oscillatory Sliding Line Contacts, Mongi Mansouri

LSU Doctoral Dissertations

This research deals with an experimental and numerical investigation of the frictional and thermal behavior of pin-bushing pairs, operating at reciprocating sliding motion or under heavy loads. Large interfacial temperatures developed due to frictional heating can cause failure. Therefore, numerical prediction and analysis of the surface temperature under various operating conditions are important. Laboratory tests using a pin-bushing tester provided measurements of the friction coefficient and temperature. Hard coated and plain (uncoated) bushings, both made of induction hardened stainless steel, were tested. Lower coefficient of friction and surface temperature were observed in the case of the coated bushing. In the ...


Characterization Of Advanced Composites- A Nondestructive Approach, Phani Surya Kiran Mylavarapu Jan 2007

Characterization Of Advanced Composites- A Nondestructive Approach, Phani Surya Kiran Mylavarapu

LSU Doctoral Dissertations

Adhesively bonded sandwich structures comprising of particulate composites as core and graphite epoxy skins as stiffeners are widely used for various applications in the marine and aerospace industry. The core material and the stiffener are held together by an adhesive bond. Particulate composites are made from a mixture of a polymer resin and hollow or solid particles. Hollow particulate composites are known as syntactic foams. Particulate composites possess attractive mechanical and physical properties such as high compressive strength etc, making them attractive materials for use in structural applications. Characterization of the adhesive bondline and core material in sandwich structures is ...


Flow Field And Heat Transfer Analyses Of Mechanical Seals, Zhaogao Luan Jan 2007

Flow Field And Heat Transfer Analyses Of Mechanical Seals, Zhaogao Luan

LSU Doctoral Dissertations

Mechanical seals are widely used in rotating equipment such as pumps, turbines and agitators to prevent leakage. One crucial factor for keeping seals reliable is the thermal behavior of the seal rings. The existing literature on thermal effects in seals primarily concentrates on the conduction of heat into the rings. Yet, a more complete analysis requires understanding of the flow field around the rings. In this dissertation, both the laminar and turbulent flows within the seal chamber are studied and their effects on the heat transfer in the seal rings are evaluated. Based on extensive sets of numerical simulations, heat ...


Granular Contact Lubrication: Theory And Experiment, Karim El Kholy Jan 2007

Granular Contact Lubrication: Theory And Experiment, Karim El Kholy

LSU Doctoral Dissertations

This dissertation is devoted to a theoretical and experimental study of the granular contact lubrication, both. The theory is based on the kinetic of the granular material where the granules interact with each other and with the boundary surfaces through instantaneous, binary collisions, characterized by a constant coefficient of restitution. Specifically this study focuses on granular lubrication in Couette flows. A series of simulations is reported and the results show good agreement with several published papers. Also, a theory that ties the true temperature to the grain mobility is developed. The true temperature of a granular material depends on the ...


Turbulence Modeling For Film Cooling Flows, Asif Hoda Jan 2007

Turbulence Modeling For Film Cooling Flows, Asif Hoda

LSU Doctoral Dissertations

An improved two equation turbulence model has been developed in this dissertation to better predict the complex film cooling flow field that is formed from the interaction of a coolant jet and a crossflow over a modeled turbine blade surface. Film cooling of turbine blades is commonly employed to effectively protect turbine blades from thermal failure and thereby to allow higher inlet temperatures in order to increase the efficiency of gas turbine engines. Film cooling involves the injection of rows of coolant jets from slots on the surface of a turbine blade which is then bent over by the crossflow ...


Measurements And Computations Of The Flow In Full-Scale Sugar Evaporative-Crystallizers And In Lab-Scale Models, Luis Fernando Echeverri Jan 2007

Measurements And Computations Of The Flow In Full-Scale Sugar Evaporative-Crystallizers And In Lab-Scale Models, Luis Fernando Echeverri

LSU Doctoral Dissertations

The circulation of massecuite is a key factor in achieving efficient heat transfer and crystallization in sugar evaporative crystallizers, and should be as high as practically possible for recovery, quality, and capacity reasons. This research report presents results on the circulation obtained applying modern experimental and numerical techniques. The main goals are contributing to expand the understanding of the process in sugar crystallizers; developing realistic models for the simulation of the circulation; and studying the effect of different design parameters. The circulation of massecuite is driven by buoyancy force due to density difference between the vapor generated and the surrounding ...


Development Of Micropump For Microfluidic Applications, Dong Eun Lee Jan 2007

Development Of Micropump For Microfluidic Applications, Dong Eun Lee

LSU Doctoral Dissertations

This dissertation covers the research work on two types of micropumps, one is based on magnetohydrodynamic (MHD) principle that utilizes Lorentz force for actuation, and the other is based on electrochemical actuation. The AC-type MHD micropump was designed and analyzed as a solution to the bubble formation problem encountered in DC-type MHD micropump. A UV-LIGA process using thick layer of SU-8 negative photoresist was successfully developed to microfabricate the AC MHD micropump. Preliminary studies and tests of the AC MHD micropumps demonstrate that bubble formation was significantly reduced to permit the proper function of the micropump. A continuous flow was ...


Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang Jan 2007

Micro Injection Fuel/Air Premixer/Combustion, Jian Zhang

LSU Doctoral Dissertations

Lean premixed (LP) combustion has become the dominant industrial approach to reduce NOx emissions. Homogeneous mixing of lean fuel and air mixtures prevents the presence of undesirable localized regions of near-stoichiometric fuel/air mixtures, thereby allowing a reduction in thermal NOx. A new concept, a multi-point micro injection premixer, is presented in this dissertation. The multi-point micro injection premixer is a porous plate that provides a simple but extremely effective method to mix air and fuel. An array of fuel jets is injected in a direction perpendicular to the plane of the premixer plate into an oncoming counterflow stream of ...


Eigenvalue Optimization And Its Applications In Buckling And Vibration, Srinivas Gopal Krishna Jan 2007

Eigenvalue Optimization And Its Applications In Buckling And Vibration, Srinivas Gopal Krishna

LSU Doctoral Dissertations

Eigenvalue problems are of immense interest and play a pivotal role not only in many fields of engineering but also in pure and applied mathematics. An in-depth understanding of this class of problems is a pre-requisite for vibration and buckling analyses of structures. Design optimization of structures to prevent failure due to instability (bucking) and vibration introduces the problem of determining optimal physical parameters such that load carrying capacity or the fundamental natural frequency is maximized. A classical example of such problems is the Lagrange problem of determining the shape of the strongest column against buckling. The primary objective of ...