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Adaptive Multi-Fidelity Modeling For Efficient Design Exploration Under Uncertainty, Atticus J. Beachy
Adaptive Multi-Fidelity Modeling For Efficient Design Exploration Under Uncertainty, Atticus J. Beachy
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This thesis work introduces a novel multi-fidelity modeling framework, which is designed to address the practical challenges encountered in Aerospace vehicle design when 1) multiple low-fidelity models exist, 2) each low-fidelity model may only be correlated with the high-fidelity model in part of the design domain, and 3) models may contain noise or uncertainty. The proposed approach approximates a high-fidelity model by consolidating multiple low-fidelity models using the localized Galerkin formulation. Also, two adaptive sampling methods are developed to efficiently construct an accurate model. The first acquisition formulation, expected effectiveness, searches for the global optimum and is useful for modeling …
Design And Manipulation Of A Power-Generating System With High-Temperature Fuel Cells For Hypersonic Applications, Jack Randolph Chalker
Design And Manipulation Of A Power-Generating System With High-Temperature Fuel Cells For Hypersonic Applications, Jack Randolph Chalker
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Current hypersonic vehicles tend to be incapable of producing onboard power with traditional generators due to their use of supersonic combusting ramjets (scramjets). Because of this, they seek additional energy sources for supporting advanced electronics or other auxiliary power-dependent devices while requiring elaborate thermal management systems to combat temperatures exceeding 700ºC. The incorporation of Solid Oxide Fuel Cell (SOFCs) stacks is an efficient solution, capable of generating large quantities of power through the use of natural fuel sources at high temperatures. Developments in this thesis include the design, construction, and support of a system operating at hypersonic-environment conditions with a …
Design And Implementation Of Periodic Unsteadiness Generator For Turbine Secondary Flow Studies, Nathan James Fletcher
Design And Implementation Of Periodic Unsteadiness Generator For Turbine Secondary Flow Studies, Nathan James Fletcher
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A primary source of periodic unsteadiness in low-pressure turbines is the wakes shed from upstream blade rows due to the relative motion between adjacent stators and rotors. These periodic perturbations can affect boundary layer transition, secondary flow, and loss generation. In particular, for high-lift front-loaded blades, the secondary flowfield is characterized by strong three-dimensional vortical structures. It is important to understand how these flow features respond to periodic disturbances. A novel approach was taken to generate periodic unsteadiness which captures some of the physics of turbomachinery wakes. Using stationary pneumatic devices, pulsed jets were used to generate disturbances characterized by …
Power/Thermal Interaction Within An Adaptive Turbine Engine, Andrew K. Desomma
Power/Thermal Interaction Within An Adaptive Turbine Engine, Andrew K. Desomma
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Usually power take off (PTO) with a two-spool turbofan engine has been accomplished via the high pressure (HP) shaft and bleed air from the high-pressure compressor (HPC). The PTO is used to run various aircraft components such as generators and hydraulic pumps, which also produce waste heat. To better understand the coupled transient nature of balancing engine thrust, power take off and thermal management, a transient variable cycle three stream turbofan engine model has been developed to investigate the integrated behavior. The model incorporates many dynamic features including a third-stream heat exchanger as a heat sink for thermal management and …