Some Studies on Argon, Helium, and Carbon Dioxide with an Integrated-Schlieren Instrumented Shock Tube

Abstract

Using integrated-schlieren instrumentation, an investigation has been made of shock waves in argon, helium, and carbon dioxide. In argon and helium a residual signal has been observed, which is ascribed to curvature of the shock front in the vicinity of the wall. A discussion is presented of the way in which the curved shock satisfies the boundary conditions, and of the resulting flow pattern, which includes a ``pressure adjustment region.'' Preliminary measurements on the variation of the apparent ``zone thickness'' with density and shock speed in these gases are reported. The importance of the observed shock curvature in measurements of the vibrational relaxation time for gases like carbon dioxide is considered. Preliminary results for the vibrational relaxation times of dry CO2 are reported for temperatures up to about 900°K, and are compared with results obtained by others.