Ultra-fast-framing schlieren system for studies of the time evolution of jets in supersonic crossflows

Abstract.

A new ultra-fast camera system is used to study the time evolution of jets in supersonic crossflows via schlieren imaging. The commercial high-speed camera includes eight independent intensified charged couple devices (ICCDs) and is capable of acquiring images at rates up to 100 MHz. A long-duration (up to 200 µs) xenon flashlamp is used as the continuous light source. The exposure times of the ICCDs and the interframing times were designed to achieve schlieren images with high spatial and temporal resolution. Example data are presented for a hydrogen jet injected into a high total enthalpy supersonic crossflow, generated using a short-duration impulse facility (expansion tube). The large-eddy convection characteristics of the jet, its penetration and the unsteady nature of the shock wave around it are analyzed. Temporal correlations, such as the movement of organized (coherent) structures and fluctuations in the bow-shock, are readily perceived by assembling the eight consecutive images as a movie (http://navier.stanford.edu/hanson/propulsion/scramjet/movies/t1179.html).