Title: Scale model store release at Mach 1.5

Description: The release of a scale model store into a Mach 1.5 free-stream flow is observed using a hi-speed schlieren photography system filming at a frame rate of 4000 Hz. The knife edge of the schlieren system was set to provide imaging of gradients in the streamwise direction. The flow is from right to left. The model store was designed using "light scaling" and the ejection force was on the order of 38 Gs. The model was released from a rectangular cavity with a depth of 2 inches, a length of 12 inches, and a width of 4 inches. Acoustic measurements showed that the unsteady shear layer over the cavity had a prominent oscillation at approximately 810 Hz. This period of repetition can be observed in the images to correspond to fluctuations in the shock-waves both from the leading edge of the cavity and around the model store. The video demonstrates the unsteady nature of the store release event along with the relative difference between the time scales of the cavity pressure oscillations and the residence time of the store in the shear layer.

Credits: Store model and ejection system desiged by Mr. Roger Birkbeck, senior design engineer, CRAFT Tech. Research conducted with the help of Mr. Bernard Jansen, senior R&D engineer, and Mr. Matthew Joachim, R&D engineer, at the National Center for Physical Aco

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Contributed By: Nathan E. Murray, Ph.D., Research Scientist & Research Assistant Professor of Mechanical Engineering, National Center for Physical Acoustics, University of Mississippi