Open AccessMixture-fraction measurements with femtosecond-laser electronic-excitation tagging
Author(s) -
Benjamin R. Halls,
Naibo Jiang,
James R. Gord,
Paul M. Danehy,
Sukesh Roy
Publication year - 2017
Publication title -
applied optics
Language(s) - English
Resource type - Journals
ISSN - 0003-6935
DOI - 10.1364/ao.56.000e94
Subject(s) - femtosecond , jet (fluid) , nitrogen , materials science , laser , excitation , analytical chemistry (journal) , fraction (chemistry) , optics , nitrogen laser , atomic physics , chemistry , physics , thermodynamics , organic chemistry , chromatography , quantum mechanics
Tracer-free mixture-fraction measurements were demonstrated in a jet using femtosecond-laser electronic-excitation tagging. Measurements were conducted across a turbulent jet at several downstream locations both in a pure-nitrogen jet exiting into an air-nitrogen mixture and in a jet containing an air-nitrogen mixture exiting into pure nitrogen. The signal was calibrated with known concentrations of oxygen in nitrogen. The spatial resolution of the measurement was ∼180 μm. The measurement uncertainty ranged from 5% to 15%, depending on the mixture fraction and location within the beam, under constant temperature and pressure conditions. The measurements agree with a mixture fraction of unity within the potential core of the jet and transition to the self-similar region.