Experimental investigation of soot concentration distribution in an aero-engine combustor using two-color laser-induced incandescence

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The spatiotemporal distribution of soot concentration in aero-engine combustor is important for assessing its combustion performance. Here, we report experimental measurements of soot concentration in terms of Soot Volume Fraction (SVF) and its spatiotemporal distribution in a single-sector dual-swirl aero-engine combustor using Two-Color Laser-Induced Incandescence (2C-LII). It is shown that soot predominantly forms in the symmetrical vortices of the primary combustion zone, exhibiting a V-type distribution with higher concentration in the lower half of the zone than the upper half, with a small amount distributed in the secondary recirculation zone. Soot emissions at the combustor outlet are relatively low under three typical operating conditions by LII experiments, which is aligned with Smoke Number (SN) from gas analysis. The effect of inlet air temperature on SVF distribution and dynamics in the primary combustion zone is studied, which suggests that the SVF level in the primary combustion zone monotonically increases with the temperature. Meanwhile, the SVF distribution becomes more symmetrical as the inlet temperature increases, although the overall SVF level in the lower half of the zone is still higher. We also investigate the influence of the inlet air pressure on the SVF distribution at the combustor outlet. The soot concentration at the combustor outlet increases with inlet pressure, mainly distributed irregularly across both sides and the center. On both sides, the distribution is continuous, while the center exhibits dot-like and linear patterns. Numerical simulations correlated SVF distribution with the flow field in the primary combustion zone, qualitatively explaining the observed SVF distribution behavior. These results under various conditions can provide valuable insights for improving the performance of this specific combustor and designing high-temperature-rise combustors in the future.