Limitations on High-Spatial Resolution Measurements of Turbulence Using Femtosecond Laser Tagging
2015 by Princeton University. Published by the American Institute of Aeronautics and Astronautics, Inc. The study of the smallest scales of turbulence requires high-resolution spatially-resolved measurements of velocity. Femtosecond Laser Electronic Excitation Tagging (FLEET) provides high-spatial-resolution, minimally-invasive velocity measurements in unseeded air flows, offering both a new method for characterizing turbulence and a potential tool for studying the interaction of turbulent flow with localized energy addition. To clarify the resolution limits achievable with FLEET, we quantify the density and temperature perturbation caused by the laser-gas interaction and examine the statistics of small-scale turbulence measured with FLEET for effects of the perturbation. We combine experimental measurements with a simple numerical model of the interaction of turbulence with a density perturbation. Our results suggest that the perturbation caused by FLEET does not cause errors in velocity measurement for length scales longer than 100 microns.