Investigation of the impact of stagger angle mistuning on the unsteady flow in a transonic rotor at a near stall condition

Abstract The effect of stagger angle mistuning on the unsteady flows within a transonic rotor at a near stall condition was studied. A mistuned configuration with 0.1 degrees of alternate stagger angle mistuning, together with a tuned configuration, was analyzed. On the one hand, the mistuning reduces the aerodynamic performance in terms of total pressure ratio and isentropic efficiency slightly. On the other hand, the mistuning expands the stall boundary of the rotor. The nodal diameter of the unsteady flows near the blade tip in the tuned system increases when the operating point approaches the stall boundary, which finally develops into a rotating stall. However, in the mistuned system, the nodal diameter variation of the unsteady flows near the blade tip is suppressed by the stagger angle mistuning. Thus, undesired unsteady flow components characterized by a specific nodal diameter can be suppressed by introducing intentional stagger angle mistuning.