We describe a newly commissioned Ludwieg-tube facility at the University of Maryland, capable of producing high-speed multi-phase flows. The wind tunnel is operational at Mach 3.75–4 for unit Reynolds numbers spanning \(\sim\) 2.5 \(\times\) 10 \(^{6}\) m \(^{-1}\) to \(\sim\) 24 \(\times\) 10 \(^{6}\) m−1, with steady test times between 30 and 40 ms, and an average startup time of 15 ms. A particle-size characterization study is performed for droplets produced from a 5% volume concentration of Di-Ethyl-Hexyl-Sebacate (DEHS) in methanol, resulting in known conditions for monodisperse DEHS droplet sizes ranging from 4.1 to 15.6 μm. Fluorescence spectroscopy is used to measure the particle concentration in the test section. The results for the particle concentration distribution are presented along with data showing the repeatability of tests. Numerical simulations for particle transport through the nozzle are used to inform tunnel design and corroborate results from the spectroscopy experiments.
