Experimental investigation on flow, fuel, and flame in an aviation model combustor with primary holes at elevated pressure

In this paper, simultaneous measurements using particle image velocimetry (PIV)/OH-planar laser-induced fluorescence (OH-PLIF) combined with fuel-PLIF testing are employed to obtain, data on the flow field, OH concentration field, and fuel concentration field of a typical combustor with primary holes under heated and pressurized conditions for the first time. The interaction between the primary jets and swirling flow is analyzed for both non-reacting and reacting operating conditions under variable fuel-air ratios (FARs). Combustion reactions accelerate the internal gases within the combustor, ultimately resulting in distinctly different flow field structures under non-reacting and reacting operating conditions. As the FAR increases in the experiments, the flame stabilization mechanism also changes. At low FAR, combustion reactions primarily occur within the primary recirculation zone (PRZ), with the flame stabilized in the shear layer where the PRZ intersects with the corner recirculation zone. However, as the FAR increases, unburned fuel returns to the PRZ with the primary jets to participate in reactions, while another portion participates in reactions in the secondary zone. At this point, combustion instability occurs. Proper orthogonal decomposition modal analysis reveals that this leads to enhanced fuel pulsation, further complicating the flow and combustion characteristics within the combustor.