Numerical Study About Buffet Characteristics and Attenuation of Vertical Tail at High Angles of Attack

In the present study, detached eddy simulations were conducted to investigate buffet characteristics of the vertical tail. Unsteady flow phenomena were observed to clarify the cause of buffet onset. The location of vortex breakdown was also predicted. Simulations were carried out for high-angle conditions of more than buffet onset. Finally, to attenuate buffet intensity, two design parameters involving the spanwise translation and the tilt angle of the vertical tail were considered. It was found that the wake-like vortex structure developed after the event of vortex breakdown was the main cause of buffet onset. It was also found that the location of vortex breakdown moves upstream with increase in an angle of attack, which accelerates dissipation of the vortex core near the vertical tail. Peak-to-peak excitation phenomenon was featured as buffet characteristics acting on the vertical tail. It was demonstrated that the factor to more excite buffet was vortex shedding originated from the trailing edge of the wing at the highest angle, in which the peak level was the largest. The most discernible effect of buffet attenuation was observed when two parameters were simultaneously applied, which are suggested as a design application under the development of aircrafts.