Flow Field Characterization of Impinged Shock Waves via Laser Absorption Spectroscopy and High-Speed Schlieren Imaging

Experiments using two small, wedged test articles were placed inside a shock tube to perturb the normal shock wave, affecting the planar flow field through the creation of weak oblique shock waves and local temperature of the experiment. A 4.9 μm quantum cascade laser captured two CO absorption features, establishing a correlation between integrated absorbance area ratios to the calculated, theoretical temperature of the experiment via Rankine-Hugoniot relations. Results demonstrate wider deviation of laser thermometry under impingement with an average temperature error of 7-10%. A classic Schlieren imaging setup was used to derive an additional calibration matrix via relations between the refractive index of the image and local density gradient across the test region. Results from this component are limited due to restrained field of view and poor image quality. Additional experiments are underway to further characterize the local phenomena via velocimetry and improved image techniques.