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Full-Text Articles in Mechanical Engineering

Fundamental Studies Of Electrochemical Reactions And Microfluidics In Proton Exchange Membrane Electrolyzer Cells, Jingke Mo Dec 2016

Fundamental Studies Of Electrochemical Reactions And Microfluidics In Proton Exchange Membrane Electrolyzer Cells, Jingke Mo

Doctoral Dissertations

In electrochemical energy devices, including fuel cells, electrolyzers and batteries, the electrochemical reactions occur only on triple phase boundaries (TPBs). The boundaries provide the conductors for electros and protons, the catalysts for electrochemical reactions and the effective pathways for transport of reactants and products. The interfaces have a critical impact on the overall performance and cost of the devices in which they are incorporated, and therefore could be a key feature to optimize in order to turn a prototype into a commercially viable product. For electrolysis of water, proton exchange membrane electrolyzer cells (PEMECs) have several advantages compared to other …


Turbine Engine Rotor Blade Damage Detection Through The Analysis Of Vibration Of Stationary Components, Jon Rylan Cox Dec 2016

Turbine Engine Rotor Blade Damage Detection Through The Analysis Of Vibration Of Stationary Components, Jon Rylan Cox

Doctoral Dissertations

Rotor blade fault detection and health monitoring systems are crucial for gas turbine engine testing and evaluation. The most commonly used techniques involve monitoring blades directly using strain gages, or drilling optical access holes in the engine casing for non-contact probes to monitor blade deflection and vibration. In this work, less intrusive, indirect techniques for rotor blade fault detection are developed, based on the hypotheses that the vibratory response of stationary components excited by the rotor blade dynamic pressure pulse can be used to detect the presence, location, and severity of rotor blade damage and changes in rotor blade natural …


Dynamic Monitoring And Life Prediction Of Internal Strain-Gage Balances, David Leon Yoder Dec 2016

Dynamic Monitoring And Life Prediction Of Internal Strain-Gage Balances, David Leon Yoder

Masters Theses

Wind tunnel test customers continue to push the limits by producing air vehicle designs that produce high aerodynamic loads at the desired test conditions. These loads are a combination of steady aerodynamic, unsteady aerodynamic, and inertial forces. A methodology to monitor the health of a wind tunnel strain-gage balance has been developed. The objective of this methodology is to define the stress limits of the balance and monitor these limits so the balance can be safely tested without failure of the balance. A balance failure could result in costly damage to the wind tunnel model, support system, and the wind …


Development, Analysis, And Optimization Of A Swirl-Promoting Mean Flow Solution For Solid Rocket Motors, Andrew Steven Fist Dec 2016

Development, Analysis, And Optimization Of A Swirl-Promoting Mean Flow Solution For Solid Rocket Motors, Andrew Steven Fist

Masters Theses

This work demonstrates and analyses a new flow candidate for describing the internal gaseous motion in simulated rocket motors. The fundamental features of this solution include the conservation of key system properties also incorporated in the classic Taylor-Culick (TC) system (i.e. inviscid, axisymmetric, steady and rotational properties), while allowing for the development of a swirling velocity component. The work compares the new solution to the development and formulation of the classic TC system, ultimately identifying that both the new and classic solutions are special cases of the Bragg-Hawthorne equation. Following this development, the text then explores the development of energy-optimized …


Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood Aug 2016

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing increased vibration …


Improved Modeling Of Atmospheric Entry For Meteors With Nose Radii Between 5cm And 10m, Jakob Dale Brisby May 2016

Improved Modeling Of Atmospheric Entry For Meteors With Nose Radii Between 5cm And 10m, Jakob Dale Brisby

Masters Theses

Atmospheric entry studies typically look closely at the peak heating rate that a body encounters during its trajectory. This is an extremely important phenomenon to study because it allows engineers to determine if a trajectory is possible with given materials and craft design specifications. It also allows designers to choose what type of method will be used for mitigating the enormous heat fluxes during entry. In general, it is accepted that during the super-sonic flight regime the body will continue to be heated and an ablative heat shield often is used to deal with these heating processes. The theory outlined …