Effect of wing on whirl flutter of propeller engine

In order to investigate the effects of wing on whirl flutter of propeller engine and reveal the underlying mechanism, the whirl flutter speed of the nacelle-propeller system and the wing-nacelle-propeller system under different structure parameters is analyzed. The strip theory is applied to calculate the aerodynamic loading of the propeller, and a method developed from MSC. Nastran is used to accomplish whirl flutter analysis. The results indicate that, the elasticity of wing structure can significantly decrease the natural frequency of engine's pitch mode, and slightly decrease the natural frequency of engine's yaw mode. This could change the difference between the natural frequencies of both modes. The degree of coupling between engine's pitch mode and yaw mode would then be influenced to cause the change in whirl flutter speed. In the case of tight coupling between the motion of the engine and the wing surface, the aerodynamic loading of the wing surface can significantly increase the whirl flutter speed of the engine.