Electron Temperature and Relaxation Phenomena behind Shock Waves

The variation of the bound electron temperature behind air normal shock waves has been investigated using a combined set of numerical and shock-tube experiments. It is concluded that for medium speed (5–7 km/sec) shock waves the magnitude of bound electron temperature is independent of the band considered, that the postshock N2 (1+) emission, while initially excited by atom-molecule collisions, is primarily controlled by vibration-electronic coupling, and that the corresponding radiative intensity profiles are not indicative of chemical relaxation but only of radiative relaxation. A method of predicting the associated bound electron temperature is presented and compared with experimental results. Finally, it is demonstrated that nonequilibrium chemistry calculations using realistic chemistry and vibrational coupling models do yield results for chemical relaxation in accordance with experimental measurements.