Shock-Tube Time-History Measurements of H2O in the H2/O2 System Using IR Laser Absorption Spectroscopy

H2O time-histories were studied within the H2/O2 system using a tunable diode laser system and a pressure-driven shock tube. Stoichiometric H2/O2 mixtures were prepared in high amounts of argon dilution. The mixtures were heated using a shock tube with a driver length of 3.04 m, a driven length of 6.78 m, and an inner diameter of 16.2 cm. A tunable diode laser (TDL) was used to measure H2O concentration near the endwall region of the shock tube after the passage of the reflected shock wave, 1.6 cm from the endwall. Both the incident and transmitted beam intensities were measured using IR photodetectors. The laser was tuned to access the H2O transition at 7204 cm^-1. Experiments in the H2/O2 system were performed from 1100 to 1500 K and at an average pressure of 2.8 atm. The experimental results were compared with a mechanism from Hong et al. (2011). Preliminary results show good agreement in ignition delay time between experiment and model. A computer routine was created to modify the absorption coefficient as a function of temperature to account for the temperature variation during the experiment due to the chemical reaction. After rescaling, the corrected H2O profiles showed excellent agreement with the chemical kinetics model. Topics related to mechanism validation, the potential effects of impurities, and measurement accuracy are also addressed in the thesis