Analysis of a Fluttering Delta Wing with Large Deformation at Low Subsonic Speeds

The problem of low subsonic delta wing flutter was studied experimentally and numerically. Two kinds of oscillation: low- and high-amplitude oscillation modes were observed in experiment. Moreover, the transition velocity between the two modes significantly depends on angle of attack. When angle of attack is high, the transition from low- to high-amplitude mode is made more suddenly. The flutter velocity obtained in the present experiment shows good agreement with other experimental data as well as results of the present computation. In addition, the flow field around an oscillating delta wing with large deformation is made clear, where vortex motion is coupled with wing motion. It is found that aerodynamic force produced by the vortex near the wing leading edge is closely related with the large amplitude wing oscillation.