Mistuning Effects on Aero-elastic Stability of Axial Compressor Rotor Blades

Abstract

The mistuning effects on the aero-elastic stability of axial compressor rotor blades have been investigated by employing aero-elastic eigenvalue method. An axial compressor rotor suffered from flutter failure has been analyzed with four intentional mistuning patterns and their sensitivities to random mistuning. Through a comparison of four intentional mistuning patterns, the mistuning mechanism of improving aero-elastic stability may be understood from the combining effects of frequency offset and the destruction of periodicity by the introduction of mistuning. Increasing the amount of alternate mistuning cannot provide any additional improving effects on the aero-elastic stability when the mistuning amount reaches a critical value. However, the further mistuning effects can be obtained by placing several groups (isolation zone) with additional frequency offset relative to the alternately mistuned system. The random mistuning can always improve the aero-elastic stability of the tuned system. However, for the intentionally mistuned system, the inclusion of random mistuning with a small level may weaken the improving effects of intentional mistuning and even makes the system unstable.