Splitter Blades as an Aeroelastic Detuning Mechanism for Unstalled Supersonic Flutter of Turbomachine Rotors

Abstract

A mathematical model is developed to demonstrate the application of splitter blades as an aeroelastic detuning mechanism for unstalled supersonic flutter of turbomachine rotors. The splitters introduce both aerodynamic and structural detuning, thereby leading to enhanced aeroelastic stability. The aerodynamic detuning is due to the variable circumferentially spaced splitters between each pair of full chord airfoils, with aerodynamic detuning due to alternate circumferential spacing of the full chord airfoils also considered. The structural detuning arises from the lower natural frequencies of the splitters as compared to that of the full chord airfoils. The enhanced torsion mode flutter stability due to the incorporation of splitters into a rotor design is demonstrated by applying this model to two unstable baseline twelve-bladed rotors which are based on Verdon’s Cascade A and Cascade B configurations. In each case, the unstable baseline rotor is stabilized by the introduction of appropriate splitters. The critical parameters for this stability enhancement are the chord length and the circumferential and axial locations of the splitters.