Vibrationally Relaxing Research Articles

Spectrum-Line-Reversal Temperature Measurements Through Unsteady Rarefaction Waves in Vibrationally Relaxing Oxygen

Abstract : Pressure and spectrum-line-reversal temperature measurements were made of the structure of an unsteady expansion wave initiated in a vibrationally-excited gas in a shock tube by the rupture of a second diaphragm. With oxygen initially at about 2500 deg K and 0.75 atmospheres pressure the vibrational temperature was observed to fall from its initial (fully-frozen) value at the tail of the wave to a minimum before rising again to the original equilibrium value at the head of the wave. This agrees broadly with Appleton's calculations based on a linear rate law and Landau-Teller theory for Tau sub v, although the temperature minimum was slightly higher and occurred later than he predicted; it was also predicted qualitatively by Stulov. More detailed studies with, for example, nitrogen would be desirable for seeking a full explanation of the small differences with theory revealed by these preliminary tests.