Numerical Simulation of Three-Dimensional Hypersonic Turbulent Flows

Advanced experimental methods that can provide quantitative flow field imaging data in hypersonic flows are required for the development of advanced hypersonic technology and the validation of compuational fluid dynamic codes. To satisfy this requirement an evaluation of potential improvements in the electron-beam fluorescence technique used for planar flow visualization in the 20-inch hypersonic wind tunnel at Wright Laboratories will be conducted. Methodologies for improvement in the measurement of the density, rotational and vibrational temperature of molecular nitrogen will be evaluated in the context of the existing electron-beam source, imaging system, and wind tunnel operating characteristics. Essential features of the electron-beam fluorescence technique to be used in the evaluation include: beam propagation charcteristics, spatial resolution, simulation of fluorescence spectra and signal level, and minimum measurement time requirements to maintain an acceptable signal-to-noise ratio. Recommendations will be provided on the design characteristics of an appropriate electron-beam fluorescence imaging system and associated image processing schemes to obtain quantitative flow field measurement of gas density and temperature in a hypersonic flow.