LIBS and Chemiluminescence Measurements for Fuel/Oxidizer Mixing Monitoring

Real-time monitoring of local equivalence ratio is of primary importance for chemical combustion efficiency improvement. In this context chemiluminescence and LIBS measurements have been presented and performed in premixed and diffusion flames. The ratio of radicals chemiluminescence emission is proved to be related to equivalence ratio in premixed flames. H/O LIBS measurements giving the ratio of two characteristic spectral lines of fuel and oxidizer is also related to the equivalence ratio. In this work, the calibration curves of radicals chemiluminescence as well as LIBS measurements versus equivalence ratio have been derived for premixed flames. Moreover, the application to diffusion flames is here considered and for both sets of measurements the calibration curves derived from premixed measurements have been applied. Results concerning the equivalence ratio evaluation in the diffusion flame by using LIBS measurements have been compared with those obtained from chemiluminescence at the external cone. These results are discussed in the text.