Property and Velocity Measurements in a Supersonic/Hypersonic Flow

This work presents a non-intrusive laser-based diagnostics technique to measure instantaneous thermodynamic properties and velocity in a compressible fluid flow. The fluid is irradiated with a pulsed narrow-bandwidth Nd:YAG laser at 532 nm. Light scattering from a point in the flow field is collected over a solid angle of about + or - 20 degrees and focused into a narrow line on an intensified CCD camera using an anamorphic optical system. A molecular iodine filter absorbs the radiation at different degrees with angles, thus producing different intensity levels on each pixel along the line. A portion of the light is split and focused on the same CCD chip unfiltered, thus providing an intensity reference from which the fluid density is found. The scattering spectrum and Doppler frequency shift are dependent on the observation angle and fluid properties, and so the values of pressure, temperature and streamwise velocity at every laser pulse using a well-known scattering model. Presented at the AIAA Aerospace Sciences Meeting and Exhibit (44th), held in Reno, NV, on 9-12 Jan 2006. Based on a Major Report by MAJ Huffman, submitted to the Air Force Institute of Technology (AFIT), Wright-Patterson AFB, OH, and published as report no. CI04-1722.