SIMULTANEOUS RAMAN-SCATTERING AND LASER-INDUCED FLUORESCENCE FOR MULTISPECIES IMAGING IN TURBULENT FLAMES

A multispecies imaging technique for single-shot, simultaneous measurement of the OH, CH, and CH, concentrations in turbulent nonpremixed flames is described. A unique aspect of the system is the use of a two-wavelength multipass cell to form both a visible and a UV laser sheet. The UV beam is used to excite fluorescence in the OH molecule, while Raman scattering from CH4 molecules and fluorescence induced in CH is achieved by using the visible beam. The visible and UV lasers are operated simultaneously, and the resulting signals are recorded by two vidicon cameras. The sheet intensity provided by the multipass cell is sufficient to saturate the OH transition, which makes single-shot, laser-saturated fluorescence imaging measurements possible.