ONE-DIMENSIONAL UV-RAMAN IMAGING OF A JET-A-FUELED AIRCRAFT COMBUSTOR IN A HIGH TEMPERATURE AND PRESSURE TEST CELL: A FEASIBILITY STUDY

UV-Raman diagnostics are complementary to other laser-based methods. We obtained one-dimensional Raman images from the flow in a high-pressure aircraft combustor. They were acquired from both single and multiple laser shots. Our goal was to see whether excimer-based Raman would work in spite of severe combustor conditions. The Jet-A fuel that was used causes difficulties because it contains polyaromatic hydrocarbons (PAHs). Some fundamental problems might have prevented successful Raman imaging. These include (1) vaporized PAHs that can absorb much of the UV laser light, thereby weakening the laser beam; (2) PAH fluorescence that increases noise; and (3) fuel droplets that absorb and refract light and produce intense light scattering. The test rig was available for only one day. Nevertheless, the results show that a one-dimensional UV-Raman imaging method can diagnose such a combustor, operating at realistic conditions, even with single shots. We suggest some diagnostic improvements that could increase the precision considerably in future applications.