A mathemahcal model is developed to analyze the aerodynamically forced response characterlstics of a detuned rotor operating in a supersonic inlet flow field with a supersonic axial component. Alternate blade aerodynamlc detuning is considered, with the aerodynamic detuning accomplished by alternating the circumferential spacing of adjacent blades. The unsteady aerodynamics are determined by developing an influence coefficient technique which is appropriate for both aerodynamically tuned and detuned rotor configuratlons. Rotor forced response is then analyzed by combining this unsteady aerodynamic model with a single-degree-of-freedom structural model. The effects of this detuning on the forced response charactenstics of supersonic axial flow rotors is then demonstrated by applying thls model to baseline twelve bladed rotors.
List of symbols
airfoil chord gust influence coefficient of airfoil, n motion-induced influence coefficient of airfoil, n mass moment of inertia linear spring constant reduced frequency, coy dimensionless unsteady aerodynamic moment mlet Mach number dimensionless radius of gyration airfoil spacing dimensionless perturbation chordwlse velocity dimensionless perturbation normal velocity complex amplitude of gust elastic axis location measured from leading edge amplitude of airfoll oscillations complex oscillatory displacement interblade phase angle detuned interblade phase angle level of aerodynamic detuning mass ratio oscillatory frequency reference frequency