Turbulent mixing between a shock-accelerated vortex ring and its surroundings

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

When a shock wave propagates through a region occupied by different gases, it generates gas motions at the wave boundary that lead to mixing at much higher rates than would have occurred in the absence of the shock wave. Phenomena of this kind can occur in a category of jet engines designed to operate at extremely high speeds that are much higher than those used in conventional jet transport. The study of these kinds of flows is generally very challenging because flow properties such as velocity, local gas composition, and temperature vary in space and time in very complicated ways. This research project will study a simple version of this type of flow. The researchers will study the response of a vortex ring to impulsive acceleration. By the nature of the vortex ring flow field, this initial condition should contain a much more coherent, well organized, predictable and measurable vorticity field than that of the jet engine. The results will form a highly refined building block database which could be used to develop a predictive capability for the more complicated version of these flows. Graduate and undergraduate students will be heavily involved in the research, with members of underrepresented minorities recruited through different programs already existing on campus. This project also will provide education in and exposure to state-of-the-art technologies and some of the most current challenges in science and engineering. The turbulent mixing induced by the interaction of a planar shock wave with a vortex ring consisting of a gas different than its surroundings will be investigated using planar laser induced fluorescence (PLIF) and particle image velocimetry (PIV). The goal of the project is to measure some of the most relevant flow properties, including the concentrations of the two gas species and their velocities everywhere within the region where the gases mix. This objective will be pursued in two different ways: 1) measurements will be made at discrete instants in time, with very high spatial resolution, and 2) measurements will be carried out with lesser spatial resolution but using an imaging system that will allow to collect entire concentration fields at a rate of up to 20,000 fields per second. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.