Hinge Moment And Flutter Of Rotor Blade For Heavy-lift Helicopter

Heavy-lift helicopters have played more and more important role in the civil context and in the military field. The demand for heavy-lift helicopters are also increasing. In this thesis, two aspects of the work on heavy-lift helicopters have been done. One hand, the nonlinear differential equations of blade motion were derived by using the quasi-steady aerodynamic model, moderate deformation theory and Hamilton's principle. By using the finite element discretization and direct integral method, the rotor-blade hinge moment versus azimuth angles was calculated. On the other hand, the rotor blade flutter characteristics of heavy-lift helicopters were analyzed by classical flutter theory . These analysis and calculation can provide a theoretical basis for designing the small rod strength, estimating the level of the helicopter vibration and improving the control environment of the helicopter. The research work includes:(1) Discussing the source of rotor blades hinge moment, analyzing the impact of various factors over the hinge moment in forward flight, and deriving the general computing formulation of rotor blades hinge moment(2) Deriving the nonlinear differential equations of blade motion by using the quasi-steady aerodynamic model, moderate deformation theory and Hamilton's principle. The Chorpa's 15 DOF element was used to discrete the equations.(3) Using the direct integral method to solve the equations. the rotor-blade pitch moment versus azimuth angles in different advance ratio was calculated by the general computing formulation.The general characteristics of Heavy-lift helicopters'hinge moment was analyzed.(4) Analyzing the flutter critical speed versus effective gravity center in different advance ratio of heavy-lift helicopters rotor-blade by using classical flutter theory, The general characteristics of heavy-lift helicopters'flutter was analyzed.