Soot-Free Low-NO_<i>x</i> Aeronautical Combustor Concept: The Lean Azimuthal Flame for Kerosene Sprays

An ultralow emission combustor concept based on “flameless oxidation” is demonstrated in this paper for aviation kerosene. Measurements of gas emissions, as well the size and number nanoparticles via scanning mobility particle sizing, are carried out at outlet, revealing simultaneously soot-free single-digit NOx levels operation atmospheric conditions. Such performance, achieved with direct spray injection fuel without any external preheating or prevaporization, attributed to unique mixing configuration combustor. The consists azimuthally arranged sprays upstream boundary reverse-flow air jets injected from downstream. This creates locally sequential combustion, good hot products, a strong whirling motion that increases residence time homogenizes mixture. Under ideal conditions, clean, bright-blue kerosene flame observed, free soot luminescence. Although intermittently formed during around optimal high-speed imaging luminescence shows particles subjected long times O2-rich conditions high temperatures, which likely promotes their oxidation. As result, only 2–10 nm range measured outlet under all tested emissions completeness combustion strongly affected by splitting flow. Numerical simulations confirm trend observed experiment provide more insight into dilution.