Research On Vibration Loads Of Coaxial Rigid Rotors

Rotor is the most important component of a helicopter. As the helicopter’s aerodynamic and control surface, rotor is the main source of many helicopter dynamic problem. The vibration level of the rotor system decides the helicopter’s vibration level to a large extent. Therefore, the continuous innovation and development of the rotor system is one of the most significant development direction of the helicopter technology.In recent years, the high-speed coaxial helicopter has gained a rapid development. From the 21 st century, the Sikorsky X-2 technology demonstrator aircraft and S-97 Raider helicopter has been well tested on the basis of the XH-59 A coaxial helicopter which is demonstrated in the last century, and they perform much better than the Russian’s pride: Ka-50 coaxial helicopter. Now that the high-speed coaxial helicopter has become a research hotspot, the prediction of the rigid rotors vibration loads is particularly important.Due to the complex aerodynamic interaction of the coaxial rotors and the blades’ rigid motion and elastic deformation, the prediction of the coaxial rigid rotors’ vibration loads is one of the difficult problems for the helicopter rotor dynamics. The purpose of this paper is to establish a calculation model of coaxial rotors vibration loads. A geometrically exact beam model is set up first, and it uses nonlinear geometry formulas to describe the blade deflections. Considering the hinge rigid motions of articulated rotors, a aeroelastic coupling model is built. Then, the Pitt-Peters inflow model with aerodynamic interaction and the quasi-steady aerodynamic model are introduced to calculate the inflow and aerodynamic force. Also, rotor vibration loads are validated and analyzed through the force product method. At last, a coaxial rotor system is designed using CATIA 3D design software.