Active Suppression On Whirl Flutter Of Tiltrotor Aircraft By Wing Controlled

Tiltrotor aircraft combines the advantages of propeller and helicopter.By transitioning from helicopter mode to aircraft mode through the tilting of the rotor,it has the ability to fly vertically and large speeds.There is a serious dynamic instability problem between the rotor of the tiltrotor and the wing.The whirl flutter of the tiltrotor aircraft has always been a key issue to limit the speed of the forward flight.How to improve the forward flight speed and expand the flight envelope of the tiltrotor aircraft has always been a research hotspot.Through controlling the airfoil surface of wing,modeling simulation and experimenting,the feasibility of airfoil surface deflection to suppress the whirl flutter problem of tiltrotor aircraft is researched.Based on the Hamilton principle,this paper constructs a dynamic model of tiltrotor considering the influence of a flap mounted on the trailing-edge of wing,ang fundamental components of tiltrotor aircraft including rotor,wing and nacelle are considered in this model.Compared with the model established by Johnson,the result is acceptable.A state observer is built.On the basis of the LQR control algorithm,an active controller using the states feedback is designed to control the deflection of the flap.The feasibility of an active control methodology to suppressing the whirl flutter is researched,which utilizing the LQR algorithm to control the active deflection of the tiltrotor flap.The simulation results demonstrate that compared with the uncontrolled system,it can improve the stability.At the same time,the control method has the capability of active suppressing the vibration of wing.In this paper,a wind tunnel test model of a semi-expansion ratio tiltrotor aircraft with a fuselage is designed,which can occur the phenomenon of whirl flutter under low wind speed.The wind tunnel test of the aileron and the winglet static deflection is carried out.By comparing with the basic test data,it is concluded that the aileron static deflection can improve the whirl flutter boundary of the test model within the design angle range.The boundary increases 7%.It is proved that the airfoil surface deflection can effectively suppress the whirl flutter problem of the tiltrotor aircraft.