Bifurcation behavior and unsteady flow mechanism of limit cycle oscillation of transonic wing

Shock wave and induced boundary layer separation are typical flow nonlinear phenomena, which will cause complex aeroelastic behavior such as limit cycle oscillation, buffeting, etc. In this paper, unsteady Reynolds-Averaged Navier-Stokes solver and structural equations of motion are coupled to establish a high-fidelity aeroelastic solver. The flutter boundaries and limit cycle oscillation of two-dimensional NACA64A010 airfoil and three-dimensional Goland+wing are both analyzed by inviscid and viscous solver. It is demonstrated that there are unstable branch in inviscid limit cycle, while no unstable branches existin viscous limit cycle. The type shift of shock wave, viscous effect and other flow nonlinearities can inhibit energy transfer between flow field and structure, which may cause limit cycle oscillation.