Planar Time-Resolved Laser-Induced Incandescence for Particulate Emissions in Premixed Flames at Elevated Pressures

Abstract

Laser-induced incandescence (LII) has proven to be a useful diagnostic for studying non-volatile particulate matter (nvPM) in combustion environments. The decay of time-resolved LII (TiRe-LII) signals can be used to estimate soot primary particle sizes. While many models for time-resolved LII exist, there are currently no validated models for the combustion of Jet A fuels at high pressures. In this work, we compare the results from a TiRe-LII model with that of an in-situ extractive soot sampling technique at 1, 2.4, and 3.8 bar pressures in a laminar, prevaporized, premixed Jet A/air combustor. A single camera, single laser shot technique is used to gather planar time-series images with an ultra-high-speed camera. At the same time, soot particles are extracted from the pressurized combustor using a custom designed thermophoretic soot sampler system, and examined through a transmission electron microscope (TEM) to determine its physical dimensions. The TiRe-LII data is validated with the help of the particle size distributions obtained by processing the obtained TEM images. Thus, the model developed from this work can be used to provide estimates of soot particle sizes for complex combustor systems.