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Aerodynamic characteristics of the deformable airfoil with quazistatic subsonic flow

Grishanina T.V., Russkikh N.M.

#### Abstract:

The linear problem of deformation and aerodynamic loading of a straight wing thin airfoil of a large elongation is considered. The wing airfoil consists of an undeformed fore part and an elastic tail. The transverse displacement and the small angle of rotation of the fore part are considered to be given functions of time The transverse displacement of the elastic tail is represented by the Ritz method in the form of expansions in terms of given functions with unknown coefficients, which are taken as generalized coordinates. The aerodynamic load is determined by the theory of plane attached airflow of an airfoil with quasistationary subsonic flow of compressible gas. The equations of aeroelastic oscillations of a deformed airfoil for generalized coordinates are obtained on the basis of the principle of possible displacements. The calculations for two types of the power schemes of the elastic tail of the airfoil are performed. In the first case, the tail is formed by a thin elastic plate of constant thickness rigidly connected with the fore part, the aerodynamic shape of which is obtained by means of an overhead profiled foam. The filler in this case does not work for bending and shear and calculations are carried out for a profile with constant characteristics along the length without allowance for shear. In the second case, the elastic part of the airfoil consists of honeycomb filler working for shear and a thin skin of constant thickness, working for stretching-compression. In this case, the thickness of the elastic tail decreases linearly to zero on the rear edge. The distributions of the aerodynamic load along the chord of the deformed profile and the values of the quasistationary aerodynamic coefficients of the lift and pitch moment are obtained for the attack angle and pitch velocity of the fore part by quasistatic elimination of generalized coordinates.

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