Quantitative 2-D OH thermometry using spectrally resolved planar laser-induced fluorescence

A novel method is presented for quantitative two-dimensional temperature measurement in combustion gases. This method, namely spectrally resolved planar laser-induced fluorescence thermometry, utilizes a high-power, wavelength-tunable and narrow-linewidth CW laser to access the spectral lineshapes of a key combustion intermediate, the hydroxyl radical (OH), and enables high-fidelity and calibration-free quantification of non-uniform temperature fields in complex reacting flows. Specifically, the R1(11)/R1(7) line pair of the OH A2Σ+−X2Π(0,0) rovibronic band was probed with laser radiation near 306.5 nm, and their fluorescence ratios were used to infer temperature. Preliminary demonstrations of this thermometry method were performed in a series of burner-stabilized CH4-air flames.