Temperatur and concentration determination in flames...

Coherent anti-Stokes Raman scattering (CARS) spectroscopy has proven to be a valuable tool for measuring temperature and major-species concentration in gas-phase reacting flows. In this work, with dual-pump CARS spectra of N2, H2, CO and simultaneous temperature and concentration determination has been studied. Measurements were taken in a heated cell and in a partially premixed flame under ambient pressure, respectively. The accuracy of CARS diagnostic requires a careful determination of the line shape parameter, so a new speed memory effects model for N2-H2 mixture is developed and tested. The experimental vibrational-CARS (VCARS) spectra were evaluated with this new line shape model. The temperature and the relative H2 concentration results were compared with those calculated from an already existing model based on linear interpolation of Hussong's theory in ambient pressure region. Measurements in the cell with fixed temperature and known composition concentration were used to validate the calculation of theoretical CARS spectra for H2 with the new line width model in low temperature case. The agreement between the experimental spectra and theoretical calculation in the investigated range of the cell measurements was found to be very good, and for the H2 concentration determination with the new model is much closer to the practical value than the linear interpolation model does. Measurements in the flame showed that the temperature and relative H2 concentration could be obtained by the new line shape model over the whole temperature range, i.e. from ambient to the flame temperature, with better accuracy than the linear interpolation model. And once again, the spectra agreement between experimental and theoretical one generated by the new model is better than that of the linear interpolation model.