A numerical investigation in an axial-radial combined compressor was performed to study the superposition of rotor/stator and stator/rotor interaction and to indicate the variations of the flow angle at inlet of the downstream rotor. Three configurations, R/S/R rig with unequal moving blade numbers, R/S rig and R/S/R rig with identical moving blade numbers, were included in this research project. Efforts were focused on the superposed interaction in the stator channel, specifically the changes in the deterministic kinetic energy caused by changing blade numbers and rotor clocking. Besides, a useful mathematical model for analyzing these changes was presented. Results show that, for the compressor with unequal moving blade numbers, the position of the excitation/suppression changes with time whereas it keeps fixed position for the rig with identical moving blade numbers. But the position can be modulated by clocking when the rotors have equal blade numbers. In addition, the blade numbers and clocking position also decide the inlet flow angle for downstream radial rotor.
