Mechanical Engineering Commons^™

Molecular Modeling Of High-Performance Thermoset Polymer Matrix Composites For Aerospace Applications, Prathamesh P. Deshpande

Dissertations, Master's Theses and Master's Reports

The global efforts from major space agencies to transport humans to Mars will require a novel lightweight and ultra-high strength material for the spacecraft structure. Three decades of research with the carbon nanotubes (CNTs) have proved that the material can be an ideal candidate for the composite reinforcement if certain shortcomings are overcome. Also, the rapid development of the polymer resin industry has introduced a wide range of high-performance resins that show high compatibility with the graphitic surface of the CNTs. This research explores the computational design of these materials and evaluates their efficacy as the next generation of aerospace …

On-Ice Detection, Classification, Localization And Tracking Of Anthropogenic Acoustic Sources With Machine Learning, Steven J. Whitaker

Dissertations, Master's Theses and Master's Reports

Arctic acoustics have been of concern in recent years for the US navy. First-year ice is now the prevalent factor in ice coverage in the Arctic, which changes the previously understood acoustic properties. Due to the ice melting each year, anthropogenic sources in the Arctic region are more common: military exercises, shipping, and tourism. For the navy, it is of interest to detect, classify, localize, and track these sources to have situational awareness of these surroundings. Because the sources are on-water or on-ice, acoustic radiation propagates at a longer distance and so acoustics are the method by which the sources …

Characterization Of Hydraulic Flow Noise Induced By Spool Valves, Carter A. Paprocki

Dissertations, Master's Theses and Master's Reports

The purpose of the hydraulic flow noise research was to investigate the relationship between operational valve parameters and flow noise generation. The primary consideration was correlating the flow noise generated by the valve with the distinct valve open positions. This data would allow future valve designs to account for features that cause increased flow noise and move those features away from high flow valve displacements. By implementing this, companies would be able to design quieter hydraulic systems that will not expose operators to the current levels of sound found on machines. The experiments were conducted using two valves with different …

Development Of Advanced Models For Pre-Ignition Prediction In Gas Engines And Analytical Model For Wallfilm Evaporation, Ankith Ullal

Dissertations, Master's Theses and Master's Reports

Ever-changing regulations aimed at improving efficiency and reducing harmful emissions have resulted in many power-generation device (engine) manufacturers to adopt new strategies. Computer simulation of these new strategies of power generation requires more accurate and higher fidelity modelling tools. In the present study, two such models are developed. The first model deals with pre-ignition phenomena driven by lubricant (lube) oil in natural gas engines and the second model is relevant to prediction of wallfilm evaporation by employing analytical solutions to transport governing equations for boundary layers.

Pre-ignition in engines has been the subject of current research with the advent of …

Partially Stratified Combustion Of Natural Gas For Spark Ignition Engines, Philip S. Zoldak

Dissertations, Master's Theses and Master's Reports

In this work, the advantages of partially stratified direct injection natural gas versus premixed port-fueled injection natural gas spark ignited engines has been studied. The volumetric efficiency, ratio of specific heats and turbulent kinetic energy was found to be higher with direct injection versus port-fueled injection thus improving thermal efficiency. A background study of optical chamber experimental data was performed to develop an understanding on the effect of pressure ratio on direct injection of methane under both fully-expanded (sub-sonic) and under-expanded (super-sonic) conditions. Under-expanded jets had a noticeable advantage in terms of turbulent kinetic energy, which led to enhanced air …

Optimal Control Of Nonlinear Wave Energy Converters In Heave For Maximum Power Extraction, Kevin Nelson

Dissertations, Master's Theses and Master's Reports

The marine renewable energy community is interested in maximizing the power generated by nonlinear wave energy converters. Optimal control methods provide a tool to achieve this aim and can also help to inform the buoy design. An energy-optimal control law for a class of non-linear buoy models is derived and is shown to be singular. The solution approach is illustrated using an hourglass-shaped buoy having a cubic, hydrostatic nonlinearity. The optimal control law is only valid on singular arcs, and a method to search for these arcs is presented. Two singular arcs are found for the hourglass buoy model and …

Concept Evaluation And Development Of A Novel Approach For Integration Of Turbogeneration, Electrification And Supercharging On Heavy Duty Engines, Satyum Joshi

Dissertations, Master's Theses and Master's Reports

While many technologies such as electrically assisted turbocharging, exhaust energy recovery and mild hybridization have already proven to significantly increase heavy-duty engine efficiency, the key challenge to their widespread adoption has been their cost effectiveness and packaging. This research specifically addresses these challenges through evaluation and development of a novel technology concept termed as the Integrated Turbogeneration, Electrification and Supercharging (ITES) system. The concept integrates a secondary compressor, a turbocompound/expander turbine and an electric motor through a planetary gearset into the engine cranktrain. The approach enables a reduced system cost and space-claim, while maximizing the efficiency benefits of independent technologies. …