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S8 Engenharia Aeroespacial |
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Title:
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MULTIBLADED ROTOR HELICOPTER GROUND RESONANCE INCLUDING EIGENVECTOR ANALYSIS
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Summary :
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ABSTRACT. THE INFLUENCE OF DIFFERENT HELICOPTER PARAMETERS ON THE SELF-EXCITING, CATASTROPHIC INSTABILITY KNOWN AS GROUND RESONANCE IS STUDIED HEREIN. THE ANALYTICAL MODEL CONSIDERS A MULTIBLADED ROTOR HELICOPTER-ROTORS WITH THREE OR MORE BLADES-AND NEGLECTES AERODYNAMICS EFFECTS. IT TAKES INTO ACCOUNT TWO EQUATIONS OF MOTION SETS: ONE CONSIDERS THE LEAD-LAG DEGREES OF FREEDOM OF EACH RIGID BLADE AND THE LONGITUDINAL AND LATERAL DEGREES OF FREEDOM OF THE ROTOR SUPPORT-HUB; THE OTHER SET TAKES INTO ACCOUNT THE LEAD-LAG AND FLAPPING DEGREES OF FREEDOM OF EACH RIGID BLADE AND THE PITCH AND ROLL DEGREES OF FREEDOM OF THE HELICOPTER AS A WHOLE. RESULTS INCLUDE DIAGRAMS FOR MODAL FREQUENCY AND MODAL DAMPING AS FUNCTION OF ROTOR NONDIMENSIONAL ROTATIONAL SPEED FOR DIFFERENT ROTOR CONFIGURATIONS. MODAL FREQUENCY AND DAMPING DIAGRAMS ARE PRESENTED FOR BOTH ROTATING AND NONROTATING FRAMES OF REFERENCE ANALYSES. EIGENVECTOR PHASORS ARE PLOTTED FOR DIFFERENT REGIMES OF ROTOR ROTATIONAL SPEED. THEIR BEHAVIOR INSIDE AND OUTSIDE THE INSTABILITY REGION IS ANALYZED. INTERPRETATION OF THE PHASORS BEHAVIOR POINTS TOWARDS A LINK TO THE VERY EXISTENCE AND NATURE OF THE PHENOMENON ITSELF.
KEY WORDS: GROUND RESONANCE, DYNAMICAL STABILITY, HELICOPTER |
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Author :
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de Andrade, Donizeti 0
Pegado, Hélio Assis
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Paper View :
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