Comparison of Measured and Predicted Conditions behind a Reflected Shock

Abstract

Measured thermodynamic conditions behind reflected shocks in a gas-driven diaphragm shock tube are compared to Rankine-Hugoniot predictions. Pressures of the shock-heated neon, which contained small concentrations of spectroscopic additives, were measured by quartz transducers. Temperatures (9000-13 000°K) were simultaneously measured spectroscopically by line reversal and absolute emission techniques, while electron densities were measured by the broadening of the Balmer line Hβ. The temperature has been measured to an accuracy of ±1.5%, while electron densities have been determined with an accuracy of ±10%. Pressure measurements attained accuracies of ±5%. The consistency of the data indicates that a homogeneous local thermodynamic equilibrium model is an adequate description of the shock-heated gas. The state measurements, compared with the real gas Rankine-Hugoniot predictions, show significant departures. Predicted temperatures are typically 3% ± 10% higher than those measured. The predicted electron density is as much as ±30% in error, and the predicted pressures are systematically lower than those measured by approximately 7% ± 15%.