A simplified approach to multi-scalar imaging for turbulent premixed flames

This paper describes and demonstrates the ability to image temperature fields and multiple chemical species simultaneously with diagnostic equipment that is common amongst university based combustion research laboratories. Specifically, using a single Nd:YAG laser (Quanta-Ray GCR-170), a dye-laser (Lumonics HD300), and two intensified cameras, high-quality planar laser-induced fluorescence (PLIF) images of formaldehyde (CH2O) were acquired simultaneously with PLIF images of either CH, OH, or a combination of CH and OH in extremely turbulent premixed methane-air flames. Acquiring these images with rather common diagnostic equipment was facilitated by the fact that strong transitions in the C-X (0,0) band of CH (near 314 nm) lie in the vicinity of strong lines in the (0,0) and (1,1) bands of the OH A-X system. Additionally, Rayleigh scattering images were acquired simultaneously with these PLIF images by implementing a second Nd:YAG laser and an un-intensified camera. However, it would be possible to conduct these measurements with a single Nd:YAG laser capable of delivering, say, ~1 Joule at 532 nm.