Planar laser-induced incandescence for the study of soot production in a multi-sector RQL Jet A combustor

Understanding the production of non-volatile particulate matter (nvPM), which is composed primarily of soot, is critical not only for reducing emissions but also for improving engine performance. While there has been significant prior work studying the fundamentals of soot formation, there is significantly less work that investigates soot formation with realistic aeroengine geometries, injectors, and fuels in high pressure conditions. In this work, soot production in a three-sector rich-quench-lean (RQL) aeroengine combustor is studied with Jet A fuel. Global equivalence ratios ranging of 0.10 to 0.20 and pressures ranging from 2.7 to 6.9 bar absolute (40 to 100 psia) are tested. In order to characterize in-situ soot production near the fuel injectors, two-dimensional laser-induced incandescence is utilized to estimate single-shot and average soot volume fractions. Time-resolved laser-induced incandescence is then used to create single camera and single laser-shot incandescence decay time images in order to infer how soot particle sizes evolve. Results show a significant increase in soot production at higher global equivalence ratios and higher pressures. Incandescence decay times, however, do not change significantly over the same range of conditions. These measurements can not only help understand soot distributions in practical RQL systems but also help improve future aeroengine combustor designs.