Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 57 for “"Jet Engines"”.
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Water ingestion in jet engines.
Civil aircraft engines are required to operate reliably in a variety of inclement weather situations. Ingestion of airborne water has been found to cause problems for certain engine types, particularly during aircraft descent at low engine power settings. The effects of water ingestion under these …
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Evaluating approaches to detecting ice accretion in and around turbofan jet engines.
… of ice crystals in the compressor stages of a jet engine causes power loss events during flight that could potentially become catastrophic. The electromagnetic properties of ice clouds make them nearly undetectable to radars and hence the need for a new sensing technique. A microwave radiometer …
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A Predictive Methodology for Soft Impact Damage in Jet Engines Incorporating Hybrid Composite Structures
… crashworthiness analysis of advanced jet engine forward sections, containing hybrid and composite structures, when subjected to soft impact. Bird strike onto the fan assembly is chosen as the impact event to be studied. The aim is to develop a numerical methodology capable of …
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Modelling of Direct Hydrogen Combustion in Jet Engines: System-Level Analysis, Computational Fluid Dynamics and Chemical Reactor Networks
L'abstract è presente nell'allegato / the abstract is in the attachment
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In-Situ Investigations of Calcium-Magnesium-Aluminosilicates (CMAS) Infiltration Effects on Thermal Barrier Coatings Under Extreme Environments Replicating Jet Engines
… or volcanic ash, are ingested by gas turbine jet engines during operation. When operating within high abundance regions, these particulates negatively interact and degrade the high temperature thermal barrier coatings (TBC) protecting underlying superalloy turbine blades vital to engine …
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Measuring ice accretion with a microwave radiometer.
Ice accretion inside jet engines is a major threat to modern aviation. Ice crystals in the atmosphere can be ingested by turbofan jet engines and build up inside reducing airflow through the engine. A reliable method to detect ice inside the engine before power loss occurs is needed. A passive …
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A New Method for Generating Swirl Inlet Distortion for Jet Engine Research
Jet engines operate by ingesting incoming air, adding momentum to it, and exhausting it through a nozzle to produce thrust. Because of their reliance on an inlet stream, jet engines are very sensitive to inlet flow nonuniformities. This makes the study of the effects of inlet nonuniformities …
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Investigation on the Performance Characteristics of Two Valveless Pulse Jets Operating in Phase Opposition
… investigation done on a single valveless pulse jet engine at the University of North Dakota by Roger W. Engebretson. It was thought that if two of these engines could be coupled in such a manner that they would fire alternatively, the performance per engine could be improved. A literature search …
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Fuel Droplet Optical Diagnostic Techniques for Lean Premixed Prevaporized Aeroengine Combustors
… at reducing the environmental impact of CST jet engines. Because these engines require lower pressure and bypass ratios, they tend to consume more fuel and produce higher emissions compared to their subsonic counterparts. One promising solution is the lean prevaporized premixed (LPP) …
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Development of a Plasma Spray Process Monitoring System through Aeroacoustic Signal Analysis
… spray coatings are vital to the capabilities of jet engines. They allow engines to operate at combustion temperatures that would otherwise melt the superalloy components. Coatings tighten clearance between rotating components, increasing engine compression. They prevent chemical attack and …
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Predicting jet engine component wear to enable proactive fleet maintenance
… driver of maintenance costs for commercial jet engines is the replacement of components that, upon inspection, are determined to be damaged beyond their repairable limits. In order to better predict the lifetime cost of maintaining engines through its flight hour agreement program, Pratt & …
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Improving the manufacturing yield of investment cast turbine blades through robust design
… by aerospace companies that design and build jet engines. Aerospace companies have found that casting defects are an important cost driver in the price that they pay the foundries for the turbine blades. Defect types include porosity, stress, grain, fill, and mold-related defects. In order to …
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Fatigue behavior of ceramic matrix composites at elevated temperatures under cyclic loading
… and reliability for man-rated systems such as jet engines, fiber reinforced ceramic matrix composites are needed. An elevated temperature axial testing system is developed to investigate and characterize fatigue behavior of Nicalon fiber reinforced enhanced silicon carbide matrix. composites at …
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Experimental Investigation and Modeling of Scale Effects in Micro Jet Pumps
… devices, beginning first with microscale jet engines and a generation later more broadly encompassing MEMS devices which generate power or pump heat. Due to small device scale and fabrication techniques, design constraints are highly coupled and conventional solutions for device …
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Hydrothermal processing of high-lipid biomass to fuels
… high energy-density fuels needed for diesel and jet engines. However, current schemes for producing these biofuels require large amounts of energy and solvents to recover the oil. The feedstocks have dilute concentrations (1 wt% or less) in aqueous media, and must be dewatered significantly to …
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Assessing the impact of historical operational data from complex assets on predictive maintenance models
… maintenance models used by commercial turbofan jet engines. Because some engines have operated for decades, their entire operational records are not in the appropriate digital format and not utilized by current models. This research identifies alternate, available sources of this data. The …
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Nonlinear dynamics of three dimensional fluid flow separation
… devices, including diffusers, airfoils and jet engines. The systematic study of flow separation dates back to the seminal work of Prandtl in 1904. He showed that a two-dimensional steady flow separates from a no-slip boundary at points where the wall shear vanishes and admits a negative …
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Aerodynamic design of an aspirated counter-rotating compressor
A primary goal in compressor design for jet engines is the reduction of size and weight. This can be achieved by increasing the work output per stage, thereby reducing the required number of stages. In this thesis, the aerodynamic design of a high speed compressor that produces a pressure ratio of …
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Computational modeling of brittle impact erosion mechanisms
… promote the formation of oxide layers in jet engines. In fluidized bed boilers, the bed materials and piping of slurries and caustic materials cause erosion and corrosion. The process of erosion-corrosion may result in material loss and damage. Proper analytical modeling of the …
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Visualizing Interior And Exterior Jet Aircraft Noise
… the noise generation mechanisms of a jet aircraft is a crucial first step toward developing the most cost-effective noise and vibrations abatement methods. In this investigation, the Helmholtz Equation Least Squares (HELS) based nearfield acoustic holography will be used to understand …
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