Below are items from the 48th DCASS, held 28 February 2023.
Dye Injection into Turbulent Water
Mark Johnson, Hang Yi, and Zifeng Yang
Wright State University
Comparison between dye visualization captured during the experiment and the dye visualization generated with the Computational Fluid Dynamic simulation.
Oxide Formations on Additive Manufactured Molybdenum
Matthew R. Gazella, Marc D. Polanka, and Ryan A. Kemnitz
Air Force Institute of Technology
Post-test SEM image of flat platelets and needle-shaped oxides on additive manufactured molybdenum that endured isothermal testing in the AFIT Burner Rig facility. The combustion conditions were representative of gas turbine environments.
Laying an expensive egg: A shadowgraph image of detonation wave expansion out of a detonation tube
Naibo Jiang and Sukesh Roy
Spectral Energies LLC
This image is selected from a shadowgraph movie with 2MHz rate. This image is 10 us after the detonation wave out of a 1/2" diameter detonation tube. The image shows the detonation wave expansion and propagation.
Fireball
Andrew Killian and Sidaard Gunasekaran
University of Dayton
Michael Mongin and Albert Medina
Air Force Research Laboratory
This video shows a rhodamine dye visualization of vortical gusts generated in the University of Dayton Water Tunnel. A gust generator consisting of a cylinder with a flat plate mounted at its trailing edge was oscillated about its center to enforce vortex shedding. Embedded dye ports on the cylinder released the fluorescent dye seen here to reveal the beautiful flow structures that look a bit like fireballs.
An Unavoidable Collision of a Reflected Shockwave and Fast Flame Structure
Benjamin Millard and Daniel Cuppoletti
University of Cincinnati
Timothy Ombrello
Air Force Research Laboratory
Collision of a lean propane-nitrous oxide fast flame and a reflected shock caused by the diffraction of a detonation. A shockwave enters from the right followed by the flame structure. The shock collides the wall on the left of the frame and reflects with this reflection colliding with the flame structure. This collision causes a localized detonation to form on the bottom surface which climbs up left wall and reinitiates the flame back into a detonation. The black and white background is Schlieren images of the event with the color that is overlayed being Chemiluminescence corresponding to CH* band. The flame was initially too weak to show up in the Chemiluminescence images but the increased intensity cause by the shock-flame collision is captured. The video is taken at 250,000 FPS with the length of the video only corresponding to just over 0.5 ms of real time.