10 kHz Acetone Molecular Tagging Velocimetry in a Mach 4 Ludwieg Tube

10 kHz molecular tagging velocimetry (MTV) in a M∞ = 4 Ludwieg tube is done using a partial pressure of acetone seeded into the facility driver tube prior to operation. Despite using air as the primary operating gas, the resulting emission of the written MTV line is long-lived, which is desirable for flow tagging. Excitation is done with the fourth harmonic (266 nm) output of an Nd:YAG pulse burst laser. Velocimetry measurements are done in the freestream, the turbulent boundary layer on the tunnel floor, and on a hollow cylinder-flare model. The turbulent boundary layer measurements are compared to a Sun and Childs turbulent boundary layer profile. Furthermore, an analysis based on expansion wave dynamics in the driver tube is presented showing that the acetone seeding used here has no impact on the tunnel gas dynamics.