The scalar-field imaging of a hypersonic mixing flow is performed in a mixing facility that is shock tunnel driven. The instantaneous mixture-fraction field of a hypersonic two-dimensional mixing layer (<i>M</i><sub>1</sub> = 5.1, <i>M</i><sub>2</sub> = 0.3) is determined with a temperature-insensitive planar laser-induced fluorescence technique with nitric oxide (NO) as the tracer species. Single-shot images are obtained with the broadband excitation of a reduced temperature-sensitivity transition in the <i>A</i><sup>2</sup>∑<sup>+</sup> ← <i>X</i><sup>2</sup>Π<sup>1/2</sup> (0, 0) band of NO near 226 nm. The instantaneous mixture-fraction field at a convective Mach number of 2.64 is shown to be nearly identical to a typical diffusive process, supporting the notion of gradient-transport mixing models for highly compressible mixing layers.
© 2003 Optical Society of America
(260.2510) Physical optics : Fluorescence
(280.2490) Remote sensing and sensors : Flow diagnostics
(300.2530) Spectroscopy : Fluorescence, laser-induced
(300.6280) Spectroscopy : Spectroscopy, fluorescence and luminescence
Tobias Rossmann, M. Godfrey Mungal, and Ronald K. Hanson, "Nitric-Oxide Planar Laser-Induced Fluorescence Applied to Low-Pressure Hypersonic Flow Fields for the Imaging of Mixture Fraction," Appl. Opt. 42, 6682-6695 (2003)