Contact-surface tailoring in real shock tubes

SUMMARY To obtain steady and well-defined conditions behind reflected shocks, the contact surface is often tailored. This is usually done by calculating the operating conditions that should produce tailoring, and by recording a pressure history to confirm the absence of pressure excurs'ions due to interaction of the reflected wave with the contact surface. Pressure records are presented to show that the equilibrium pressure (p ) after interaction can easily be confused with the tailored reflected pressure Tp ), if the records are only considered quali- tatively. been made for carbon dioxide plus argon (C02 + Ar) and carbon dioxide plus argon plus helium (C02 + Ar + He) mixtures, and for nitrogen (N2), driven by He. Plots of pe/p5 at an M, quite different from the calculated value. Consideration of real gas effects in the tailoring calculation does not eliminate the discrepancy. How- ever, if the actual relation between diaphragam pressure ratio and M is sub- stituted for the ideal relation ordinarily assumed in tailoring calcuLtions, accurate predictions of the tailored