Date of Award

2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Advisor

Ferguson, Frederick

Abstract

Methodologies required for the creation of an aircraft design tool capable of generating practical hypersonic vehicle configurations based on the waverider design concept were developed and validated. The design space for these configurations was formulated by using an algorithm that coupled the directional derivatives to the conservation laws to produce flow fields in the form of organized sets of post-shock stream-surfaces. This design space is used to construct ideal waverider configurations with a sharp leading edge. A carving methodology was also developed to transform the idealized waverider geometry into practical aircraft configurations with blunted leading edges for hypersonic mission applications. Further, methodologies, based on both empirical and analytical relations, were developed and implemented to evaluate the resulting aerothermo-dynamic performance of the resulting hypersonic aircraft configuration. In this dissertation, methodologies to determine the local pressure, skin-friction and heat flux were also developed, implemented and validated. For example, in regions where the surfaces of vehicle configuration allow for the use of planar models, the flat plate viscous relations for compressible flow were implemented in the evaluation of the local skin friction and heat flux quantities. However, in other regions, such as, the blunted leading edges, flat plate viscous relations are not applicable, and in those regions the modified Newtonian theory, Fay-Riddell theory and Modified Reynolds analogy were applied. At every stage of the creation of this design tool, the newly develop methodologies were validated using existing analytical solutions, empirical relationships, and independent computer simulation. For example, the set of streamlines that represents the inversely created hypersonic flow field generation by the technique developed herein compared particularly well to exact Taylor-Maccoll solution. Similarly, the observed relationships between the local Stanton number and skin friction coefficient with local Reynolds number along the 2 idealized region of the vehicle surface compared extremely well to that of experimental findings. Of particular importance to this dissertation is the creation of an automated grid generation methodology. For the purposes of independent CFD simulations, structured mesh, orthogonal to both the vehicle surface and the free stream, can be generated around the resulting hypersonic vehicle configuration. In addition, based on the users’ requirements the grid information can be exported to appropriate CFD codes in their respective format. The efficacy of the grid generation methodology and the capability of the newly created hypersonic vehicle tool were analyzed. Overall, the independent CFD simulations compared well with the data predicted by the hypersonic vehicle design tool. In the areas of external flow field comparison, both methods, the independent CFD simulations and the vehicle design tool, closely recovered the exact solution described by the Taylor-Maccoll solution. In addition, the pressure distribution on the vehicle surface compares extremely well. However, the distribution of the viscous-related surface properties generated by the two methods showed some disagreements in the neighborhoods of the blunted edges. These preliminary results indicate that there may be room for improvements in the aerothermo-dynamic analysis methodologies implemented on the blunted regions.

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