The evolution of the flow topologies of 3D separations in the stator passage of an axial compressor stage

► Topological analyses of oil-flow results were conducted at four operating conditions. ► Evolution processes of 3D separation flows along operating line were established. ► Exact 3D flow structures were reconstructed at different conditions. ► Four basic types of flows were found to compose the complicated 3D flows. ► SPIV results were used to validate the topological analyses.