Dynamic Properties And Responses Of Heavy-Lift Helicopter Tail Rotor

The analysis of dynamic properties and dynamical response such as the natural frequency, mode shapes and the forced vibration response of tail rotor blades under aerodynamic force play an important part in tail rotor dynamic design. In this thesis, the multi-body dynamics simulation based on MSC.ADAMS was used to analyze the dynamic properties and dynamic response of heavy-lift helicopter tail rotors.First of all, the equations of flapping and lead-lag motion of tail rotor blades were formulated by using Newton method to analyze and describe its dynamic properties. Next, for a heavy-lift helicopter, the natural frequencies and mode shapes of flapping and lead-lag motion of its tail rotor blades under different rotating speed were obtained by using multi-body dynamics simulation and a Campbell diagram of flapping and lead-lag motion was made according to the natural frequency. The results which the Campbell diagram indicates are in accordance with the theoretical analysis.With respect to the problem of dynamic response, first of all, the relationship expression of aerodynamic loads was built. While the induced velocity in hover was computed by combining momentum theory and blade element theory, the induced velocity in forward flight was computed by using the linear inflow models. Finally, the aerodynamic loads were manipulated so that they can be applied to the tail rotor blades in the form of modal force in MSC.ADAMS. Next, the multi-body dynamic simulation of dynamic response of tail rotor blades was performed, and in addition to the displacement and deformation of blades in hover, the flapping velocity and displacement of blades in forward flight were obtained. Theoretical analysis indicates that all these results are in accordance with practical case.