Description And Flow Characterization Of Hypersonic Facilities

Hypersonic test facilities will continue to play a major role in the development of hypersonic vehicles. In the past, ground test facilities were often used to perform configuration parametric studies and/or to develop large databases. Future testing will emphasize understanding of fluid physics and validation of codes. Computational fluid dynamics (CFD) has made great progress in the past two decades, but the marriage of CFD and ground testing is clearly a reality today, and will become even more important in the future. One of the challenges for the experimentalist is to develop and utilize facilities that simulate hypersonic flight, and to provide the required data precision to validate CFD codes. This provides a brief review of facility fundamental considerations and simulation issues. It is clear that no one facility will meet the wide variety of test objectives; therefore, the test facilities span a range of size, run time, complexity, and operating cost. Representative facilities are described, as well as their test capabilities, flow quality, and deficiencies. Computational fluid dynamics (CFD), Ground testing, High-Enthalpy facilities, Aerodynamic testing, Aerothermal testing.

In this paper, an array of converging-diverging nozzles in parallel is designed to create a highly turbulent, sufficiently mixed flow for the study of turbulent-compressibility effects and assist in the ongoing work of oblique detonation wave (ODW) research. Several nozzle array candidates were designed with varying numbers of nozzles and nozzle sizes and evaluated using computational fluid dynamics to determine which candidate produced the most viable conditions for investigating turbulent compressibility effects. Conditions and design restrictions of the nozzle arrays were tailored to the conditions set in the Hypersonic Wind Tunnel, which is located at the Propulsion and Energy Research Lab at the University of Central Florida.

Flow field and drag characteristics of several laminar boundary layer tripping element in hypersonic flow.

Bringing together most of the expertise available throughout the world on the instrumentation for the characterization of hypersonic flows, this work reviews fundamental requirements and points out the necessity for low uncertainties, especially for code validation and the assessment of real gas effects.

Formulation and application of a windward surface flow-field (inviscid and viscous) analysis is presented for general lifting body configurations at high angles of incidence under hypersonic perfect gas conditions. The technique applies a strip theory concept, leading to an infinite extent yawed body treatment applied in the windward surface crossflow plane for both the inviscid and viscous (boundary layer) flow fields. The boundary-layer analysis is based on the governing equations for yawed blunt body boundary layers.

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A hypersonic-wind-tunnel nozzle concept which incorporates a hot-core flow surrounded by an annular flow of cold air offers a promising technique for maximizing the model size while minimizing the power required to heat the test core. This capability becomes especially important when providing the true-temperature duplication needed for hypersonic propulsion testing. Several two-dimensional wind-tunnel nozzle configurations that are designed according to this concept are analyzed by using recently developed analytical techniques for prediction of the boundary-layer growth and the mixing between the hot and cold coaxial supersonic airflows. The analyses indicate that introduction of the cold annular flow near the throat results in an unacceptable test core for the nozzle size and stagnation conditions considered because of both mixing and condensation effects. Use of a half-nozzle with a ramp on the flat portion does not appear promising because of the thick boundary layer associated with the extra length. However, the analyses indicate that if the cold annular flow is introduced at the exit of a full two-dimensional nozzle, an acceptable test core will be produced. Predictions of the mixing between the hot and cold supersonic streams for this configuration show that mixing effects from the cold flow do not appreciably penetrate into the hot core for the large downstream distances of interest.