CALCULATION AND EXPERIMENTAL STUDY OF STALL FLUTTER BASED ON NONLINEAR AERODYNAMICS

The dynamic stall in the flight of the aircraft with a large angle of attack will lead to the self-excited torsion or pitch motion of the structure, causing nonlinear stall flutter, which will directly affect the flight safety and structural safety of the aircraft. In current study, the standard Leishman-Beddoes nonlinear unsteady aerodynamic model is modified by Mach number to make it suitable for the calculation of dynamic stall aerodynamic in the case of low speed incompressibility. Then, based on the two-element segment aeroelastic model, Newmark time-domain propulsion method is adopted for the calculation of engineering stall flutter. The stall flutter wind tunnel test is designed and completed based on the calculation results. The experimental results show that the stall flutter calculation results based on L-B model are in a good agreement with the experimental results in most experimental cases. The research results also verified that: the modified L-B model can be used for stall flutter engineering analysis and for the limit cycle oscillation evaluation of low-speed aircraft with high aspect ratio, and the stall flutter speed and limit cycle amplitude are considerably affected by the initial angle of attack at the same time.