Characterization of turbulence by Air Photolysis And Recombination Tracking (APART)

In this paper we discuss the possibilities of Molecular Tagging Velocimetry (MTV) method called APART for fundamental turbulence research. We have investigated relevant characteristics of the method such as signal intensities, lifetime of the tagged molecules, spatial resolution and velocity resolution to determine whether the method is suitable for measuring turbulence over a large range of scales. Tagging is done at the outflow of a strongly turbulent free jet. It is shown that 2 mJ/pulse is minimally needed to create LIF in the 4 mm2 'read' area. Tagging lines down to 50 μm cross section can now be reached. Using a Gaussian fit algorithm velocities with an accuracy of 0.8 ms-1 can be calculated.