“…Swirling flows provide benefits such as flame stabilization and increased mixing, and understanding soot formation in these systems is of the utmost importance. Extensive work using laser diagnostics has been done on swirl stabilized, turbulent flames, premixed and non-premixed, using mostly gaseous fuels with some more recent work looking at liquid fuels (Wang et al 2019a, b;Stöhr et al 2019;Geigle et al 2011Geigle et al , 2013Geigle et al , 2015aGeigle et al , b, 2017Roussillo et al 2018). Geigle and coworkers have looked at the effect of equivalence ratio, thermal power, pressure, and secondary air injection on soot formation in swirl stabilized, turbulent non-premixed ethylene-air flames (Stöhr et al 2019;Geigle et al 2011Geigle et al , 2013Geigle et al , 2015aGeigle et al , b, 2017.…”