Experimental study the effect of flare sleeve length on the flowfield and spray characterization of a combustor swirl cup

The two-phase flow field of combustor dome with double swirlers, venturi and flare sleeve was studied experimentally using two-dimensional particle dynamics analyzer (PDA). The velocities, diameter, volume flux of droplets were measured, while the effects of the flare sleeve length on the flow field and atomization were analyzed. The flowfield downstream created by flare sleeves with different lengths is of the same structure, which includes central recirculation zone and corner recirculation zone. The flare sleeve length controls the development of flow field and affects the attachment point of the flow, which moves downstream with the increase of the length. The size of the recirculation zone is biggest when the flare sleeve length reaches a critical value. The Sauter mean diameters (SMD) produced by the shortest flare sleeve are smallest in the recirculation zone, showing good atomization. The atomization improves outside the recirculation zone with the increase of the flare sleeve length. The spray cone angle decreases with the increase of the flare sleeve length. The selection of the optimum sleeve length depends on the needs of combustion performances.