Publications

Burst-mode spontaneous raman thermometry in a free-piston shock tube

Winters, Caroline W.; Lynch, Kyle P.; Kearney, S.P.; Daniel, Kyle; Wagner, Justin W.; Haller, Timothy; Varghese, Philip

A high-speed thermometry diagnostic based on spontaneous Raman scattering (SRS) was demonstrated using a pulse-burst laser at a 3-kHz data acquisition rate, with a pulse duration of 200 ns and wavelength of 532 nm. The technique was evaluated in a challenging free-piston shock tube environment operated at conditions up to 1653 K and 112 bar following an incident shock Mach number of 3.5 and a reflected shock Mach number of 2.2. The SRS thermometry resolved the temperature in post-incident and post-reflected shock flows and clearly showed cooling associated with driver expansion waves. A detailed spectral physics model inferred temperatures within 1% of the predicted post-shock temperatures, when SNR was greater than 2.0. This was a significant advancement of spontaneous Raman vibrational thermometry.