On characterizing nonequilibrium at the shock-front in shock tube experiments with pure oxygen

摘要

A combustion-driven shock tube is designed and tested to produce high speed and high temperature shock waves. This tube will be used to perform optical spectroscopy to measure nonequilibrium thermodynamic quantities on high temperatures test gases produced by single shock waves. A mixture of hydrogen, oxygen, helium, and argon is ignited in the driver section obtaining incident shock wave Mach numbers in the range of 6.4—19 (2100—6300 m/s). Pure oxygen is used as test gas. The repeatability of the shock velocity is below 1.3%. The effects of the diaphragm thickness, driver gas composition, and initial pressure in the driven on the shock velocity are investigated. For all the cases with the exception of the driven pressure, linear behavior is observed. A power low dependence appears to exist between initial driven pressure and incident shock wave Mach number. An optical diagnostic technique is setup to perform absorption spectroscopy for the measurements of vibrational temperatures across the shock wave.