Two-color volumetric laser-induced fluorescence for 3D OH and temperature fields in turbulent reacting flows

Single-shot, two-color, volumetric laser-induced fluorescence was demonstrated for three-dimensional (3D), tomographic imaging of the structural properties of the OH radical and temperature field in a turbulent hydrogen- air flame. Two narrowband laser sources were tuned to the Q₁(5) and Q₁(14) transitions of the (1,0) band in the A²Σ → X²π system and illuminated a volumetric region of the flame. Images from eight unique perspectives collected simultaneously from each of the two transitions were used to reconstruct overlapping OH fields with different Boltzmann fractions and map the 3D temperature distribution with nanosecond precision. Key strategies for minimizing sources of error, such as detector sensitivity and spatial overlap of the two fields, are discussed.