Quantitative multi-line NO-LIF temperature imaging

A novel temperature-imaging technique based on laser-induced fluorescence of nitric oxide is presented, analyzed and applied. Multi-line rotational thermometry is combined with an efficient spectra-fitting procedure in an imaging configuration. The technique is sensitive over a wide range of temperatures and robustly applicable to different steady combustion and flow systems. Application is shown in premixed and partially premixed ethylene/air Bunsen flames with equivalence ratios between 0.7 and 3.0, and the results are compared to coherent anti-Stokes Raman-scattering temperature measurements. The technique is robust against strong elastic scattering from soot in the rich flames. It yields absolute, quantitative temperature measurements without the necessity of external calibration.