Thesis (Ph. D.)--State University of New York at Binghamton, Department of Electrical Engineering and Computer Engineering, 2006. / Includes bibliographical references (leaves 107-122).

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: vaporizer; two-phase flow; electric propulsion. Includes bibliographical references (leaves 152-156).

Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2005. / Ben T. Zinn, Committee Chair ; Jeff Jagoda, Committee Member ; Suresh Menon, Committee Member ; Tim Lieuwen, Committee Member ; Rick Gaeta, Committee Member. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on June 9, 2009) Vita. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains vii, 83 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 53-57).

An investigation, both theoretical and experimental in nature, has been undertaken to develop a simple method for the design of supersonic nozzles and, indeed, inlets of quite complex shapes from known or calculated axisymmetric flowfields. 1he axisymmetric flowfield is determined using a computer program based on the method of characteristics. Streamlines are calculated by direct integration of the axisymmetric stream function. 7he desired shape is chosen at the exit of the computed axisymmetric nozzle having the desired length and Mach number. Its describing points are then traced along the corresponding streamlines back to the throat. Streamsheets formed by these streamlines define the new shape. Following this approach, two three-dimensional nozzles were designed : one of elliptical cross-section and a two-dimensional wedge. Flows within the two configurations were further simulated using a general purpose three-dimensional CFD code, 'PHOENICS', while the elliptical nozzle was subsequently manufactured and submitted to experimental tests. Results from the experimental tests and three-dimensional numerical simulation, as well as predictions of the performance of the nonaxisymmetric nozzles and their axisymmetric counterparts were obtained and compared. Good agreement was achieved between the several components of the study demonstrating that it is possible, using this relatively simple method, to design satisfactory three-dimensional nozzles.

The performance of an aircraft gas turbine engine is adversely affected by the non-uniform or distorted flow in the inlet duct. Inlet flow distortion lowers the surge margin of the engine‟s compression system with surge occurring at much lower pressure ratios at all engine speeds. The compressor and/or engine are subjected to ground tests in the presence of inlet distortion to evaluate its performance. The simplest method of simulating inlet distortion during these tests is by installing a distortion screen ahead of the engine on the test bed. The uniform inlet flow to the compressor becomes nonuniform with total pressure loss after passing through the distortion screen. Though the distortion screens offer a number of significant advantages, they have some disadvantages. The air jet distortion system can alleviate many of the operational disadvantages encountered with the conventional distortion screens. The system consists of a number of air jets arranged in a circumferential array in a plane and issuing opposite to the primary air flow entering the engine. The jets interact with the primary stream and cause a local total pressure loss due to momentum exchange. The individual mass flow rates from the jets can be varied to obtain a required total pressure pattern ahead of the compressor at the Aerodynamic Interface Plane (AIP). A systematic study of the flow field of confined, turbulent, incompressible, axisymmetric jet issuing into counterflow is covered in this research programme. The jet penetration length and the jet width are reduced compared to unconfined counterflow and a linear relationship between the velocity ratio and the jet length ceases to be valid. The flow field of a circular compressible turbulent jet and then a system of four jets arranged circumferentially and issuing into a confined counterflow was studied experimentally and numerically. For the four jet system the mass flow rates in the four jets were equal in the first part of the study and in the second part they were unequal. The loss in total pressure due to the jet(s) interacting with the counterflow was quantified by a total pressure loss parameter λp0. The total pressure loss increased with increasing mass flow ratio. The total pressure loss distribution was evaluated at several locations behind the jet injector(s). The total pressure non-uniformity quantified by Distortion Index (DI) was found to be highest at a location just downstream of the jet injector and at far downstream locations low values of DI were observed. From the understanding gained with a single jet and four jets in counterflow a methodology was developed to generate a given total pressure distortion pattern at the AIP. The methodology employs computations to obtain the total pressure distortion at the AIP with quasi-one-dimensional inviscid analysis used as a starting point to estimate the mass flow rate in the jets. The inviscid analysis also provides a direction to the iterative procedure to vary the mass flow rate in the jets at the end of each computational step. The methodology is demonstrated to generate a given total pressure distortion pattern using four jets and is further extended to a larger number of jets, twelve and later twenty jets. The total pressure distortion patterns typical of use in aircraft gas turbine engine testing are generated accurately with a smaller number of jets than reported in the literature.

Applied research and testing has been conducted at the Cal Poly San Luis Obispo High-pressure Blow-Down facility to study the affects of throttling in a thrust-vectored aerospike nozzle. This study supports the ongoing research at Cal Poly to effectively thrust vector a hybrid rocket motor. Such thrust vectoring is achieved by small secondary ports in the nozzle body that are perpendicular to the main nozzle. The testing conducted included characterizing and comparing the performance of a straight aerospike nozzle to that of a thrust-vectored aerospike nozzle. Throttling effects on the aerospike nozzle in an unvectored and in a vectored configuration were also investigated. The interaction between throttling and thrust vectoring of an aerospike nozzle is the focus of this thesis research. This research shows that large-throat/high-thrust operation of an aerospike nozzle provides little thrust vector generation. Conversely, small-throat/low-thrust operation provides ample thrust vector generation. These results have implications in the effectiveness of thrust vectoring an aerospike nozzle with secondary ports. Rockets having an aerospike nozzle with throttling capabilities will be subject to the minimum and maximum turn angles for a given throttle position. As such, certain vehicle maneuvers might not be obtainable at certain throttle operations. Conversely, at lower throttling conditions, higher turn angles will be achievable.

In this work, laser ablation is investigated as a possible propulsion technique for space applications.

The objective of this investigation was to improve the thermal environment for a turbine vane through reduction of passage secondary flows. This was accomplished by modifying the vane/endwall junction to include a leading edge fillet. The problem approach was to integrate optimization methods with computational fluid dynamics to optimize the fillet design. The resulting leading edge fillet was then tested in a large-scale, low speed cascade to verify thermal performance. A combustor simulator located upstream of the cascade was used to generate realistic inlet conditions for the turbine vane. Both computational and experimental results underscore the importance of properly modeling the inlet conditions to the turbine. Results of the computational optimization process indicate that significant reductions in adiabatic wall temperature can be achieved with a leading edge fillet. While the intent of the initial fillet design was to improve the thermal environment for the vane endwall, computational results also indicate thermal benefit to the vane surfaces. Flow and thermal field results show that a fillet can enhance coolant effectiveness, prevent formation of the leading edge horseshoe vortex, and preclude full development of a passage vortex. In experimental testing, four cascade inlet conditions were investigated to evaluate the effectiveness of the fillet in reducing endwall temperature levels. Two tested conditions featured a flush combustor/cascade interface, while the remaining two included coolant injection through a backward-facing slot. With the flush interface, fillet thermal performance was evaluated for two inlet total pressure profiles. For the design profile, the fillet had a positive impact on the endwall temperature distribution as well as on the passage thermal field. For the off-design profile, the fillet was observed to have a slightly detrimental impact on the endwall adiabatic temperature distribution; however, passage thermal field results indicate a thermal benefit for the vane suction surface. With the backward-facing slot, thermal tests were conducted for two slot coolant flow rates. For both slot flow rates, the fillet improved endwall thermal protection and prevented coolant lift-off. While increasing the flow rate of slot coolant enhanced endwall effectiveness, fillet thermal performance was similar for the two slot flow rates. / Ph. D.