Unsteady Numerical Investigation on Vortex Interaction between Rim Seal Purge Flow and Upstream Stator .

To assess unsteady vortex interaction between rim seal purge flow and upstream stator, numerical investigations were conducted under different purge flow rates. The vortex distributions for the stator and cavity were investigated and the interaction processes near the cavity exit, in particular the vorticity change resulting from the ingress and egress, were analyzed. Results show the intensity of hub passage vortex (HPV) and hub trailing shedding vortex (HTSV) at stator exit is decreased as a consequence of enhancing blockage effects caused by the egress flow. However, when the purge flow rate increases, from stator exit to downstream of cavity exit, the reduction in the intensity of two vortices is weakened as the extrusion of egress flow thins their vortex tubes. The vortex inside the cavity is generated as the combined effect of relative rotation of cavity walls and nonuniform circumferential pressure mainly imposed by upstream stator. The ingress leads the positive axial vorticity near the stator hub to ingest into the cavity and eject into the main passage due to the blockage of purge flow. Furthermore, the interaction between the ingress of the mainstream and purge flow produces local negative axial vorticity. The egress flow carries negative axial vorticity mainly originated from the rotational cavity wall, and enters into the main flow passage near the rotating hub, then locations of HPV and HTSV move to the mid-span slightly with the extrusion of egress flow. [ABSTRACT FROM AUTHOR]