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 36 for “"flowpath"”.
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Evaluation of Mixing-Limited Quasi-Global Wind-US Model for HIFiRE 2 Flowpath
… for static pressure along the engine flowpath is found to be within approximately 10%, for the two lowest Mach number cases, without calibration. Key features of the numerical flowfield development are identified, including regions within the combustor found to be significantly …
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Numerical Investigation of Scaling Effects of a Ramjet-Powered Projectile
<p>Ramjet flowpath miniaturization is a potentially useful technology for integration into munitions to increase range, accuracy, and lethality. The emphasis of this effort is to numerically characterize the performance of a miniature hydrogen-fueled and ethylene-fueled ramjet flowpath during Mach …
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A combined cycle approach to dual-mode scramjet design and analysis
… which is fundamentally comprised of a high-speed flowpath with no moving parts, belies its structural simplicity with the attendance of incredibly rich fluid and flame dynamics that govern its design and operation. While great strides have been made towards characterizing the important physical …
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Characterization of turbine rim seal flow and its sealing effectiveness
… turbine engine, ingestion of hot gas from the flowpath into the gaps between the turbine rotor and stator can lead to elevated metal temperatures and a deterioration of component life. To prevent ingestion, bleed air from the compressor is used to "purge" the rim seal cavities. Establishing a …
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Flameholding methods for compact hypersonic systems
… were tested in an axisymmetric Mach 2.6 flowpath to assess their performance in combination with a cavity flameholder. It was observed that the hypermixer geometries enhanced fuel-air mixing and flameholding through turbulent flame production as well as an enhancement of cavity activity, …
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Mechanical design of an experimental aspirated compressor
… row by control of the boundary layers within the flowpath. The low speed fan stage is designed to produce a pressure ratio of 1.5 at a tip speed of 700 ft/s. Any boundary layer that could limit the performance of the stage is controlled by suction at the location just upstream of the strong …
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The physical role of transverse deep zones in improving constructed treatment wetland performance
… sections examined, between three and six narrow flowpaths were found that together carried 20-70% of the flow at a velocity at least ten times faster than the rest of the marsh. One known method for offsetting the deleterious effect of short-circuiting flowpaths is to include several transverse …
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Effect of Thermally Induced Deformation in a Supersonic Combustion Facility
… taking place within the scramjet engine flowpath. The predicted thermal deformation is used to refine the CFD model and produce a new set of results for direct comparison with experiment during both ramjet and scramjet modes of operation. Improved agreement between CFD and experiment is …
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Investigation of Grid Adaptation to Reduce Computational Efforts for a 2-D Hydrogen-Fueled Dual-Mode Scramjet
<p>A two-dimensional dual-mode scramjet flowpath is developed and evaluated using the ANSYS Fluent density-based flow solver with various computational grids. Results are obtained for fuel-off, fuel-on non-reacting, and fuel-on reacting cases at different equivalence ratios. A one-step global …
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Turbofan engine sizing and tradeoff analysis via signomial programming/
This thesis presents a full 1D core+fan flowpath turbofan optimization model, based on first principles, and meant to be used during aircraft conceptual design optimization. The model is formulated as a signomial program, which is a type of optimization problem that can be solved locally using …
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Multidimensional dynamic compression system modeling
… developed to allow post-stall modeling of split flowpath systems such as turbofans. This model was an entirely new concept. Additionally, a two-dimensional axial-circumferential model of rotating stall cell development and propagation was developed based on previous work. All of the models …
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Design of a model propulsor for a boundary layer ingesting aircraft
… work on propulsion system scaling, nacelle and flowpath aerodynamic optimization, mechanical design of the propulsor and characterization of the propulsor electric motors, all in support of the wind tunnel experiments. Explicit definition is given of those designs that meet the requirements of …
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Numerical Simulation of UVA Ramjet/Scramjet Hypersonic Engine with Hydrogen-Air Combustion Using Wind-US
<p>The internal flowpath of University of Virginia's Mach 5, direct-connect, dual-mode scramjet engine was simulated using Wind-US, a density-based Reynolds-Averaged Navier-Stokes flow solver. Detailed flowfield simulation results are directly compared to experimental data to evaluate the accuracy …
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Numerical Simulation of Mode Transition in a Hydrogen-Fueled Scramjet
… dual-mode direct-connect ramjet/scramjet engine flowpath tests conducted in the University of Virginia (UVa) Supersonic Combustion Facility (SCF). The objective was to develop a computational capability within Wind-US to aid current hypersonic research and provide insight to flow as well as …
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Runoff from hummock-covered Arctic tundra hillslopes in the continuous permafrost zone
… controlled by the saturated layer position and flowpath type. Subsurface flow follows downslope oriented flowpaths (primary and macrochannnel flowpaths), and flowpaths obstructed from conducting directly downslope (secondary flowpaths). The water velocity, discharge and residence time of the …
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Near-surface hydrology and hydrochemistry under contrasting land-cover
… to differences of the relative importance of flowpaths. This study was conducted in the southwestern part of the Brazilian Amazon basin. An intensive hydrological and hydrochemical sampling and monitoring network was set up. The results indicate that the hydrology was modified in many ways due …
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Sviluppo di strumenti per l'ottimizzazione del progetto aerodinamico di turbomacchine assiali
… della blade force sulle regioni palettate del flowpath è definibile attraverso un processo di ottimizzazione inversa. Le equazioni di Eulero contengono anche altri termini destinati a riprodurre gli effetti del bloccaggio delle pale e delle perdite di profilo. La tesi affronta in particolare …
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Epikarst control on flow and storage at James Cave, VA: an analog for water resource characterization in Shenandoah Valley karst
… recession analysis aided in delineation of flowpaths in the epikarst, including quickflow, moderate flow, and baseflow components. Hydrograph shape analysis suggests flow restrictions at two of the drip sites that may reveal spatial differences in storage capacity and retention time. Results …
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Assessing the geologic sources of manganese in the Roanoke River watershed
… flows toward the Roanoke River where the flowpath terminus is marked by elevated Mn. The inverse correlation of Mn with dissolved oxygen suggests that reducing conditions that develop along flowpaths allow for Mn to persist in groundwater. Overall, results suggest that the same processes …
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