Single-shot 3D flame diagnostic based on volumetric laser induced fluorescence (VLIF)

Single-shot three-dimensional (3D) CH₄ flame measurements based on volumetric laser-induced fluorescence (VLIF) were demonstrated. The excitation laser beam was expanded to a height of 40 mm and thickness of 10 mm to excite the CH radicals in the target flames. The VLIF method combined LIF with tomography to enable 3D measurements and single-shot measurements were shown based on CH in a 9.3 X 9.3 X 32.7 mm³ with 0.15 mm voxel size. The LIF photons emitted volumetrically were captured by five intensified cameras simultaneously and these projections were utilized as inputs to a tomography algorithm to reconstruct the 3D distribution of CH which can then be used to obtain other flame properties in 3D.Measurements were first done on stable laminar flames for comparison and validation against planar laser-induced fluorescence and then on turbulent jet flames to show the feasibility and accuracy of VLIF for instantaneous 3D flame measurements and motivate further studies.