Quantitative mixture fraction measurements in combustion system via laser induced breakdown spectroscopy

•Application of LIBS techniques in a quantitive mixture fraction measurements.•Calculation of mixture fraction from the calibration parameters for local elemental mass fraction.•The mixture fraction calculations based on the ratios of the spectral lines of H/N elements, H/O elements and C/(N+O).

Laser induced breakdown spectroscopy (LIBS) technique has been applied to quantitative mixture fraction measurements in flames. The measured spectra of different mixtures of natural gas and air are used to obtain the calibration parameters for local elemental mass fraction measurements and hence calculate the mixture fraction. The results are compared with the mixture fraction calculations based on the ratios of the spectral lines of H/N elements, H/O elements and C/(N+O) and they show good agreement within the reaction zone of the flames. Some deviations are observed outside the reaction zone. The ability of LIBS technique as a tool for quantitative mixture fraction as well as elemental fraction measurements in reacting and non-reacting of turbulent flames is feasible.