The Prediction And Analysis Of Rotor Vibration Loads Based On Aeroelastic Characteristics In The Helicopter Steady Level Flight Condition

The prediction and analysis of rotor vibration loads is one of the most critical problems duringthe development of the helicopter. Structural modeling and aerodynamic modeling is an importantprerequisite to accurately predict and analys rotor vibration loads. Choose a reasonable accurate andreliable numerical solution method is also very important. The prediction and analysis of rotorvibration loads based on aeroelastic characteristics developed in this paper. Improve accuracy andefficiency of vibration load in the helicopter steady level flight condition. It has important engineeringpractical value.The detailed work of the thesis is presented as following:(1) Structural modeling and aerodynamic modeling. Based on the Hodges moderated deflectionrotating beam theory establish structural modeling, based on quasi-steady theory establishaerodynamic modeling, considering reverse flow, mach number perturbations,noncirculatory airloads.Using Hamilton’s principle, finite element discretization thought to derive the blades-fuselage coupledstructure matrix and aerodynamic matrix, and then obtain the blades-fuselage coupled controlequations of motion.(2) Trim analysis.In this paper, Trim analysis considering the rotor hub six force element in thesteady state. In the body of the shaft, the establishment of three force (vertical force, longitudinalforce, lateral force) and three moments (pitch, roll, yaw) vehicle equilibrium equations. Set up ageneral balancing calculation method about a single rotor helicopter in the steady level flightcondition.(3)About the prediction and analysis of rotor vibration loads, In this paper, based on the basis ofthe classical modal theory, Set up aeroelastic characteristics method considering the effects ofpneumatic spring matrix and aerodynamic damping matrix.Then, the blade finite element equationsare transformed into the normal mode space. Use the temporal finite element method to get the rotorblade system response.Describe sectional vibratory loads of force summation method and modalsummation method. Then take SA349/2for example, the fundament understanding prediction andvalidation of rotor vibratory loads in steady level flight.