Flow diagnostics in unseeded air
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© 1990 American Institute of Aeronautics and Astronautics, Inc. All rights reserved. The understanding of hypersonic and supersonic flow fields is of great importance for the design of high-speed aircraft and high-speed propulsion systems. In an effort to facilitate that understanding, we present here several new approaches to the quantitative measurement of flow field parameters in high-speed flows. These techniques have been specifically developed for the study of air flows in the Mach 2 to Mach 3 regime and can be extended to the hypersonic and subsonic regimes in a straightforward manner. We show the capability of capturing instantaneous, two-dimensional, cross-sectional images of the density using ultraviolet Rayleigh scattering and measuring velocity profiles using the newly developed RELIEF technique. Preliminary results indicate that the ultraviolet Rayleigh scattering may also be extended to the measurement of velocity and temperature fields by using an atomic or molecular absorption filter window, and that the RELIEF technique can be extended to marking shaped volumetric points or arrays of points in the flow field for quantitative measurements of velocity and vorticity. Source development efforts are underway to simplify the RELIEF technique into a single laser system, and it appears possible to extend the ultraviolet Rayleigh scattering approach to volumetric imaging of time-evolving density, temperature, and velocity fields.
author list (cited authors)
MILES, R., & LEMPERT, W.
Miles, R., & Lempert, W.