The following dissertation describes an investigation of the structural response behaviour of a composite solid rocket motor nozzle subjected to thermal and pressure loading during the motor ignition period, derived on the basis of a multidisciplinary numerical simulation approach. To provide quantitative and qualitative context to the results obtained, comparisons were made to the predicted aerothermostructural response of the nozzle over the entire motor burn period. The study considered two nozzle designs – an exploratory nozzle design used to establish the basic simulation methodology, and a prototype nozzle design that was employed as the primary subject for numerical experimentation work. Both designs were developed according to fundamental solid rocket motor nozzle design principles as non-vectoring nozzles for deployment in medium sized solid rocket booster motors. The designs feature extensive use of spatially reinforced carbon-carbon composites for thermostructural components, complemented by carbon-phenolic composites for thermal insulation and steel for the motor attachment substructures. All numerical simulations were conducted using the ADINA multiphysics finite element analysis code with respect to axisymmetric computational domains. Thermal and structural models were developed to simulate the structural response of the exploratory nozzle design in reference to the instantaneous application of pressure and thermal loading conditions derived from literature. Ignition and burn period response results were obtained for both quasi-static and dynamic analysis regimes. For the case of the prototype nozzle design, a flow model was specifically developed to simulate the flow of the exhaust gas stream within the nozzle, for the provision of transient and steady loading data to the associated thermal and structural models. This arrangement allowed for a more realistic representation of the interaction between the fluid, thermal and structural fields concerned. Results were once again obtained for short and long term scenarios with respect to quasi-static and dynamic interpretations. In addition, the aeroelastic interaction occurring between the nozzle and flow field during motor ignition was examined in detail. The results obtained in the present study provided significant indications with respect to a variety of response characteristics associated with the motor ignition period, including the magnitude and distribution of the displacement and stress responses, the importance of inertial effects in response computations, the stress response contributions made by thermal and pressure loading, the effect of loading condition quality, and the bearing of the rate of ignition on the calculated stress response. Through comparisons between the response behaviour predicted during the motor ignition and burn periods, the significance of considering the ignition period as a qualification and optimisation criterion in the design of characteristically similar solid rocket motor nozzles was established. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.

No description available.

Thesis (Ph. D.)--University of Washington, 1992. / Vita. Includes bibliographical references (leaves [144]-153).

Thesis (Ph. D.)--Duke University, 2008. / Includes bibliographical references.

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 70-73).

Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2007. / Ruffin, Stephen, Committee Member ; Seitzman, Jerry, Committee Member ; Menon, Suresh, Committee Chair.

<p>Current small satellite propellant tank design is driven by three factors: volume op-timization, manufacturing capability, and propellant management. Conformal propellanttanks offer solutions to the design challenges of optimizing satellite volume and manufac-turing costs. Conformal propellant tank designs that meet these challenges have unknowneffects on propellant management. Compounding this uncertainty is the industry shift to-wards new green propellants with large contact angles. Improper propellant managementcan deliver gas to a thruster or leave propellant trapped away from the tank outlet whiledraining. Both scenarios reduce the lifespan of satellites.</p> <p>Stamping is one manufacturing process that can produce tanks that optimize volumeand are relatively easy to manufacture. The effects of the stamping process on tank shapeand propellant management is evaluated through testing four different tank geometries. Thestamping process sometimes leaves behind a seam where two sides of a tank are joinedtogether. A total of six tank and vane combinations are tested. One set of traditional tanksserve as a control. Three tanks tested share vane geometry and have different interiors toevaluate the effects of the stamping process on propellant management. The first tank hasa smooth interior, the second has a seam at the joints and the third tank has a seam andridges for increased stiffness. The last two tanks have an interior in the shape of an arc andhave different vanes. The experiment is flown on the ZeroG airplane to test the tank andvane designs in a weightless environment.</p> <p>The experiment consists of a payload rack, eleven experimental pods and one powerdistribution pod. Each experimental pod is designed to be modular and independent fromall other experimental pods. Each experimental pod hosts a camera, electrical box, secondcontainment and fluid system with four tanks.</p> <p>The results of this study show no discernible difference could be observed between tankswith or without a seam from the stamping process. When ridges are added to a tank thatare parallel to the contact line, liquid may not wick into the ridge if it is dry. If the ridgeis wet the liquid spreads out on the surface of the tank further. The differences betweenpropellant positioning for zero and nonzero contact angle fluids are discussed</p> <p><br></p>

In late 1992 coalbed methane became the most significant source of natural gas produced in Virginia. This gas is held within the coal formations adsorbed to the coal matrix. The current well stimulation technology applies a high pressure fluid to the coal formation surrounding the wellbore to induce a series of fractures. The research documented in this thesis investigates several new technologies that could replace or augment the current well stimulation approach of hydraulic fracturing. The application of liquid carbon dioxide, as the stimulation agent was investigated in a series of permeability tests. These measurements were made using a radial flow technique developed specifically for this research project. The results of the tests using liquid carbon dioxide to enhance the permeability of coal samples, to methane gas, indicated a significant increase in permeability of the samples. Comparison to a reference material showed, however, that the increase was of a general nature, not by specific interaction with the coal matrix. Rather, the permeability increase was due to reduced resistance of the borehole skin. Studies of the new, radial flow, permeability measurement approach showed good agreement to a conventional, axial flow, approach for similar sample bedding orientation to the gas flow. The documented experiments also include investigations into the potential for using custom designed nitrocellulose/nitroglycerin/RDX based propellant charges to produce extensive fracturing away from the wellbore. The first series of these experiments concerned the characterization of the burn properties for these propellants and their mixtures. Utilizing an interior ballistics approach, these laboratory small-scale shots were numerically modeled with a program written as a part of this project. Using the small-scale results and the modeled data, a series of large-scale test shots were developed and fired to gain understanding of the scale effects. The small-scale constant volume bomb, and the large-scale vented bomb were both custom designed and fabricated for this project. Comparisons of the laboratory data and modeled predictions show good agreement for both the small and large-scale test series. This work concludes by presenting considerations for utilizing the propellant based well stimulation approach in the water filled wells in southwest Virginia. / Ph. D.

It was accidentally discovered in the 1940s that the addition of lead to double-base propellants, resulted in beneficial burn rate phenomena. However, due to its toxicity the Department of Defense has been trying to find a replacement for lead over the last decade. Research efforts with this goal in mind have generally used the same methodology of either adding different metals, using different grain sizes, or using different concentrations to obtain the same burn rate effects as lead. Although some metal oxides demonstrated significant promise, they also depleted the double-base propellant stabilizer faster than acceptable, decreasing shelf life. The research explored herein does not take the same approach, but rather attempts to replace lead and solve the stability problem at the molecular level using a novel design. The new method was to synthesize a stabilizer ligand complex with a less toxic metal to create a complex that both stabilized the propellant and provides a burn rate modifying agent. First, the synthesises of two leaded complexes, tetrakis (µ3-(4-methyl-3-nitrophenyl imido lead (II))) and bis(dinitrophenyl imido lead(II)) are reported as both a proof of concept and to determine a feasible synthetic pathway. After various unsuccessful attempts using common stabilizer molecules as ligands, n-phenylurea was identified as a suitable analogous stabilizer molecule and was bonded to a cobalt center to create hexa-1-phenylurea cobalt(II) nitrate. Additionally and serendipitously, unreported complexes of metal ions with dicyanamide were discovered, which generated a discussion between ligand strength and metal center. Each of the complexes are characterized in depth and many physical properties determined. / Chemistry

M.S.