| Control surface flutter is a very typical and complicated flutter phenomenon in flutter vibration for aircraft.One of the most significant kind is flutter due to the coupling between the wing and the control surface.It is usually found from mode coupling subject to bending,and torsion of the wing and the deflection of the control surface.Stiffness and mass balance are the most important parameters which can obviously influence flutter characteristic for the wing and the control surface.Critical flutter speed can be obviously decreased due to the change of deflection stiffness and the movement of the mass center.Therefore,it is valuable and significant to study flutter characteristics of the control surface.This paper will focus on flutter mechanism of wing-control surface.According to fundamental basis of aileron flutter mechanism,a trapezoidal wing with control surface is taken as the research object,an aileron flutter design method is constructed which includes model design,manufacture and experiments.The summarized control surface flutter design process can be implemented in the flutter design of such kind of aircraft.There are mainly four parts in this paper.Firstly,the flutter motion equations of airfoils with control surface are presented.In the derivation of motion equation,the energy principle is used,and qualitative analysis is also carried out on the wing-control surface flutter phenomenon.Flutter motion equation presented a theoretical foundation for the next step including design,analysis,manufacture and experiments of the control surface model.Secondly,design method of a control surface flutter model is proposed,a model of a wing with control surface is designed with stiffness equivalence,shape similarity,wing-control surface/flap connection mechanism design and wind tunnel experimental protection device design.So trapezoidal wing structure model with low flutter boundary and easy adjustment of control surface and/flaps deflection stiffness was presented.Thirdly,by employing the present structure of the control surface model,the corresponding structural dynamics modeling is completed with FEM method.Parameterization of stiffness and mass is proposed.Structure dynamics analysis is presented based on accurate FEM model.At last,the design method of the present model is completed.The ground vibration test(GVT)was adopted on the physical model.The test experimental results were and compared with numerical results.During the design process,this parameterized finite element model was modified interactively,which was also employed for the rear wind tunnel experiments.Finally,the flutter characteristics of the FEM model were analyzed by using double lattice method.Also the flutter characteristics of the structural model were obtained by wind tunnel experiments.Numerical results were compared with the experimental results,which can verify the accuracy and reliability of the present model design method.By the effective FEM simulations,GVT and wind tunnel,it can be seen that: the main modal frequency errors of the control surface flutter model are all beneath 5%;and the flutter velocity and frequency from wind tunnel experiments are in good agreement with those of numerical results.It can verify the feasibility and reliability of the design method the control surface flutter model in this paper.This paper proposed an effective design method for wind tunnel experiments of contro surface of a wing.Also it can provide a novel design thought of dynamic experimental structures for the complicated aircraft. |
