Multiparameter spatio-thermochemical probing of flame-wall interactions advanced with coherent Raman imaging

Ultrabroadband coherent anti-Stokes Raman spectroscopy (CARS) has been developed for one-dimensional imaging of temperature and major species distributions simultaneously in the near-wall region of a methane/air flame supported on a side-wall-quenching (SWQ) burner. Automatic temporal and spatial overlap of the similar to 7 fs pump and Stokes pulses is achieved utilizing a two-beam CARS phase-matching scheme, and the crossed similar to 75 ps probe beam provides excellent spatial sectioning of the probed location. Concurrent detection of N-2, O-2, H-2, CO, CO2, and CH4 is demonstrated while high-fidelity flame thermometry is assessed from the N-2 pure rotational S-branch in a one-dimensional-CARS imaging configuration. A methane/air premixed flame at lean, stoichiometric, and rich conditions (Phi = 0.83, 1.0, and 1.2) and Reynolds number = 5000 is probed as it quenches against a cooled steel side-wall parallel to the flow providing a persistent flame-wall interaction. An imaging resolution of better than 40 mu m is achieved across the field-of-view, thus allowing thermochemical states (temperature and major species) of the thermal boundary layer to be resolved to within similar to 30 mu m of the interface. (C) 2016 by The Combustion Institute. Published by Elsevier Inc.