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Pulse detonation combustion has been of interest for many years since it offers several advantages over standard deflagrative combustion. In theory, detonative combustion is a better use of fuel compared to deflagrative combustion since less entropy is generated during a detonation. As a result, detonation offers higher pressure and temperature gain across the wave front compared to the comparable deflagration. Since a detonation is a supersonic event which uses a shock to compress and dissociate reactants, a Pulse Detonation Combustor (PDC) is a relatively simple device that does not necessarily require a large compressor section at the inlet. Despite these benefits, using a turbine to extract work from a PDC is a problem littered with technical challenges. A PDC necessarily operates cyclically, producing highly transient pressure and temperature fields. This cyclic operation presents concerns with regards to turbine reliability and effective work extraction. The research presented here investigated the implementation of a pulse detonation diffuser, a device intended to temporally and spatially distribute the energy produced during a detonation pulse. This device would be an inert extension from a baseline PDC, manipulating the decaying detonation front while minimizing entropy production. A diffuser will seek to elongate, steady, attenuate, and maintain the quality of energy contained in the exhaust of a detonation pulse. These functions intend to reduce stresses introduced to a turbine and aid in effective work extraction. The goal of this research was to design, implement, and evaluate such a diffuser using the using conventional analysis and simulated and physical experimentation. Diffuser concepts using various wave dynamic mechanisms were generated. Analytical models were developed to estimate basic timing and wave attenuation parameters for a given design. These models served to inform the detail design process, providing an idea for geometric scale for a diffuser. Designs were simulated in ANSYS Fluent. The simulated performance of each diffuser was measured using metrics quantifying the wave attenuation, pulse elongation, pulse steadying, and entropy generation for each design. The most promising diffuser was fabricated and tested using a detonation tube. Diffuser performance was compared against analytical and computational models using dynamic pressure transducer diagnostics. / Master of Science

The effect of the solid-circulation rate and pattern as well as the air-gap size on heat-transfer coefficients between a horizontal, cylindrical heater and vibrated beds of Master Beads (spherical alumina) and glass spheres was studied. Solid piles were observed to form at specific bed locations. Solid-circulation paths were directed from the shallowest toward the deepest region of the vibrated bed. For beds in which the solid pile formed above the heating surface, local solid-circulation loops were observed above and below the heater. Air gaps developed at the top and bottom of the cylindrical heater. Heat-transfer coefficients of 140-350 W/m²K in beds of glass spheres and 180-480 W/m²K in beds of Master Beads were determined for a temperature difference of 30°C between the heater and vibrated bed. The trends in the behavior of the heat-transfer coefficient could be explained in terms of a model that accounted for the air-gap size and particle renewal in the layer closest to the heater. Increased solid-circulation rates improved the heat-transfer performance until larger air-gap sizes eventually compromised any increase in solid circulation. The expansion of the interlayer spacing of H-Magadiite (a layered silicic acid) by the introduction of pillars containing silicon atoms was investigated. A trisiloxane and two trichloroorganosilane compounds were used as the pillaring agents. The interlayer space of H-Magadiite was successfully expanded by pillaring with trichloroorganosilanes. The minimum dimensions of the pores that access the interlayer space of the pillared compounds were determined as being 6.2 Å and 9.5 Å (dimensions at perpendicular directions). Pillaring of H-Magadiite at low pH and temperatures close to 0 °C yielded the highest surface areas, e.g., increasing the surface area from 35 to 130-200 m²/g. The pillared compounds were found to be thermally stable up to temperatures of 650°C. / Ph. D.

Call number: LD2668 .T4 1978 W43 / Master of Science

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