Waverider Design, Analysis and Performance Evaluation

Abstract

This paper discusses the development and validation of a suite of tools, having both both geometric and performance based characteristics, that when used in concert generate waverider configurations with realistic flying capability. The geometric tools incorporates an algorithmic coupling to the directional derivatives of the fluid dynamic conservation laws to produce flow fields in the form of organized sets of post-shock wave stream-surfaces. From these stream-surfaces, waverider configurations are construct. These performance based routines were created with the goals of efficiently and accurately evaluating the aerothermo-dynamic performance of the resulting hypersonic configurations. In efforts to continuously improve the efficiency of the waverider toolset, the numerical procedures, with capability of evaluating the local pressure, skin-friction and heat flux distribution on the hypersonic configurations, are constantly improved and validated. For example, the performance parameter tools, in regions where the surfaces of vehicle configuration allow for the use of planar models. In regions, such as, the blunted leading edges, the modified Newtonian theory, Fay-Riddell theory and Modified Reynolds analogy are applied. In general, the waverider design and evaluation code consist of a suite of elementary design algorithms that are either based on existing analytical solutions, empirical relationships, or independent computer simulation. For example, a set of streamlines that is generated from an arbitrary shockwave can also be quickly be compared to the equivalent set of streamlines generated for the exact Taylor-Maccoll solution. In a similar manner, the observed relationships between the local Stanton number and skin friction coefficient with local Reynolds number along the idealized region of the vehicle surface can quickly be compared to that of experimental findings. Of particular importance this study, is the creation of an automated grid generation tool. For the purposes of independent CFD simulations, structured mesh, orthogonal to both the hypersonic vehicle surface and the free stream, can be generated around the resulting hypersonic vehicle configuration. Additionally, as per the user’s requirements, the grid information can be exported to appropriate CFD codes in their respective format. The independent CFD simulations compared well with the data predicted by the suite of hypersonic vehicle design tools. For example, when comparing the external flow fields generated by independent CFD simulations tools to that of the hypersonic vehicle design tool, it can be observed that all the main features are recovered. In the case of conical flow fields, the exact Taylor-Maccoll solution is recovered. Additionally, in all cases, the pressure distribution on the vehicle surface compares extremely well to that from independent analysis. However, the distribution of the viscous-related surface properties generated by the two methods, the independent CFD simulations and the vehicle suite of design tools, occasionally showed some disagreements in the neighborhoods of the blunted edges. These results indicate that there may be room for improvements in the aerothermo-dynamic capability of the hypersonic design code.