|M.Sc Thesis||Department of Aerospace Engineering|
|Supervisor:||Prof. Levy Yeshayahou|
An ultraviolet Raman spectroscopic system, based on vibrational Raman scattering effect, was designed to diagnose flame temperature and species concentration.
The presented spectroscopic system can be successfully used for obtaining quantitative spectral data. The measurements provide quantitative data about the presence of major gaseous combustion species such as O2, N2, CO, CO2, H2, water vapor and unburned fuel.
Time-average diagnostics was used for point measurements of the relative species concentration and temperature of the flame in atmospheric pressure.
The relative concentration measurements were obtained from the ratio of the relevant species spectral lines strength to the nitrogen lines strength. On the base of the measured data species mole fractions have been calculated.
Temperature measurements were derived from the Raman Stokes/anti-Stokes intensities ratio and compared with the theoretical results. Spectra of the combustion species were measured in a laminar butane flame, produced by Bunsen burner, with 5 mm inlet tube diameter. For processing of the experimental data, special MATLAB programs were written. To calibrate the system, Stokes Raman scattering intensities of O2 and N2 in ambient air were measured by a time average technique with a precision photon counting system. The gaseous Raman scattering Q-branches Stokes intensities for 266 nm wavelength excited light was calculated on the base of the theoretical analysis. The theoretical calculations were compared with the experimental results. Good comparison between the analytical model and the experimental data allows usage of the system for measurement of temperature and concentrations of the major combustion species at atmospheric pressure. Measurements error of the presented system is 5-7 % for species mole fractions measurements, and 9-10 % for measurements of temperature, for the temperature range from 8000 K to 25000 K.