Air Resonance Dynamic Stability Analysis Of The Coupled Rotor/Fuselage

Air resonance is a dynamic instability phenomenon of the coupled rotor/fuselage in flight. Themain Self-excitation vibration source is the coupling of the lag-retreated motion and the block motionwhich have horizontal movement in the rotor blade hub center. A possible way of avoiding airresonance is to choose and match some design parameters.In this dissertation, for air rensonancestability analysis,a dynamic analysis model of the coupled rotor/fuselage is developed to summarizesthe characterristics of air resonance stability and regularity.The main contents are as follows:1.Basing on Hamilton’s Principle, a dynamic analysis model of the coupled rotor/fuselage isdeveloped through the multi-body method considering the coupling between various degrees offreedom. Compared with Newtonian mechanics analysis method,in this paper,the established model issystem is systemative,add the influence of each parametermore easily,in view of the inflyence of thecomponents easily and easy to implement by computer programming.2.in near balance position The linearized eigenvalue method was used for small disturbancehypothesis considering the coupling between various degrees of freedom. The steady-state response ofthe flap and lag motion, the pitch and poll motion will be worked out. The linearized equation wastransformed in to fixed frame with a numerical Fourier Coordination Transformation. The eigenvaluemethod was used to analysis the coefficient matrix. Basing on modal frequency and modal damping ofvarious vibration model, air resonance mechanism and stability of the helicopter which has no airforce influence and which has air force influence was analyzed.3. By solving specific examples,modal frequency and modal damping how do they go to changewhen the lag stiffness, the lag damper, the flag stiffness, the flag damper, the lag and flag hinge offset,the height of rotor, the inertia of body around the x, y axis change. Analyze the regularity of airresonance when these parameters change. Some useful conclusions and disciplines have beenobtained which can be used to provide the guide to dynamic design of helicopter.