Mechanical Engineering ETDs


Evan Johnson

Publication Date



We present an experimental study of a shock interaction with an initially diffuse heavy-gas cylinder seeded with submicron-scale glycol droplets. Unlike most earlier studies, the investigation covers not just a quasi-two-dimensional geometry, where the axis of the cylinder is parallel to the plane of the shock, but also the oblique interaction at an angle of 15\u25e6 between the cylinder axis and the plane of the shock wave. Our experimental data cover the range of Mach numbers from 1.2 to 2.4. The heavy gas cylinder is produced by injecting sulfur hexafluoride pre-mixed with glycol vapor into the test section of a tiltable shock tube through a co-flowing nozzle, with the gravity-driven flow of the heavy gas stabilized by an annular flow of air in the downward direction. Droplets in the gas cylinder are visualized via Mie scattering of diffuse white light. Two views of the flow—side and top— are simultaneously captured by a high-speed gated and intensified CCD camera, producing a spatially and temporally resolved description of the evolution of the gas cylinder upon impul- sive acceleration. While the observations for the planar interaction reveal that the large-scale flow structure remains largely two-dimensional, confirming the assump- tions of earlier studies, during the oblique shock interaction, we observe evidence of flow evolution in three dimensions, including asymmetric interaction of the gas cylin- der with the boundary layers forming on the walls of the shock tube, and rotation of this cylinder in the vertical plane parallel to the streamwise direction.


Gas dynamics, Shock Waves, Vortex-motion, Turbulence, Deterministic chaos.

Degree Name

Mechanical Engineering

Level of Degree


Department Name

Mechanical Engineering

First Committee Member (Chair)

Truman, Randall

Second Committee Member

Mammoli, Andrea


Defense Threat Reduction Agency

Document Type