Turbulent Mixing at the Contact Surface in a Driven Shock Wave

In a shock tube, with a bursting diaphragm, the separation of the test gas from the driver gas at the contact surface does not always occur. In this paper helium‐argon test gas mixtures are used with a helium driver to explore the role of the ratio of average molecular weight on the formation of the contact surface. The results are correlated with a theory that supposes turbulent mixing due to a Rayleigh‐Taylor instability, and a criterion or $L$ ratio is defined which predicts when the turbulent mixing is sufficient to destroy the hot gas sample of the pure test gas.