3D distribution of hot spots affected by flow and spray in a centrally staged combustor

This paper investigates the 3D distribution features of fuel, hot spots (HS), and velocity in a centrally staged swirl spray combustor using particle image velocimetry (PIV) and simultaneous fuel/OH planar laser induced fluorescence (PLIF) at an inlet pressure of 0.5 MPa and temperature of 500 K. The pilot and main stages of the combustor were supplied with RP-3 kerosene. Multiple spanwise slices of the combustor were imaged and the resultant data were used to perform 3D reconstruction of the aforementioned physical fields via an interpolation method. Through visualization of the HS in various spanwise and axial slices, as well as more quantitative analysis on the circumferentially averaged radial profiles, HS merging between the main and pilot stages was examined based on the extracted spatial trajectories. Three zones of HS evolution were identified, namely pre-merging, merging, and post-merging. In the pre-merging zone, the hot spots of the two stages exhibited independent growth. As transitioning to the merging zone, the pilot HS was gradually diverted by the pilot air jet and merged to the main HS. In the post-merging zone, the main HS was largely dominated by the unburned fuel jet cores from the main stage. These results show the importance of comprehensive analysis on the 3D characteristics of physical quantities in understanding the HS behavior. This study provides valuable experimental support for regulating HS within the primary combustion zone of centrally staged aero-engine combustors.