Numerical study of the effect of periodic jet excitation on cyliner aerodynamic instability

Numerical simulations based on the ALE finite element method are carried out to examinernthe aerodynamics of an oscillating circular cylinder when the separated shear flows around the cylinderrnare stimulated by periodic jet excitation with a shear layer instability frequency. The excitation is appliedrnto the flows from two points on the cylinder surface. The numerical results showed that the excitationrnwith a shear layer instability frequency can reduce the negative damping and thereby stabilize thernaerodynamics of the oscillating cylinder. The change of the lift phase seems important in stabilizing therncylinder aerodynamics. The change of lift phase is caused by the merger of the vortices induced by thernperiodic excitation with a shear layer instability frequency, and the vortex merging comes from the highrngrowth rate, the rapid increase of wave number and decrease of phase velocity for the periodic excitationrnin the separated shear flows.