Computational Analysis On Vibration Loads Of Coaxial Rigid Rotors Based On CFD/CSD Coupling

A CFD/CSD coupling method for analysis on the rotor vibration loads of coaxial rigid rotor is adopted by integrating structural dynamic model and aerodynamic model.The geometrically exact large deformation theory is used in structural dynamic model,fully containing the coupling relationship of all elastic deformation and with no restriction of deformation.The Hamilton principle is adopted in rotor dynamic equation.The rotor CFD model is used in aerodynamic.The coaxial rigid rotor flow field in the CFD model is constructed by using geographic division method.And the CFD model is built with the Navier-Stokes governing equation coupling with multiple mesh motion method.A rotor aeroelastic analysis method for analysis on the rotor vibration loads of coaxial rigid rotor is established by integrating structural dynamic model and aerodynamic model.The data transmission and iteration is achieved by loose coupling strategy.The rotor CFD model is validated by accurately calculating lift coefficient and moment coefficient about airfoil section in dynamic stall and aerodynamic characteristic in model rotor.It is effective in aerodynamic calculation.Comparing with the flight test data of SA349/2 helicopter,it is confirmed that this coupling method for the rotor vibration loads is accurate by calculating the flapping moment and edge moment.The improvement of the prediction accuracy of the rotor vibration loads is effectively demonstrated and the effectiveness of prediction analysis of the rotor vibration loads is validated.Finally,comparing with the flight test data of XH-59 A in wind tunnel,it is confirmed that this coupling aeroelastic analysis method for coaxial rigid rotor vibration loads is useful and accurate by comparing the flapping moment and edge moment in different advance ratio.It is further proved that the accuracy of the load calculation method in this paper.Considering the influence of coaxial rotor interaction in vibration loads calculation,conclusions are made about the influence of different flight parameters and design parameters in vibration loads calculation,which can be used in vibration reduction optimization.