Numerical investigation on high-speed jet actuation for transient control of flow separation

Abstract

Flow separation around a lifting body was controlled using a high-speed jet generated via impulsive actuation, and important flow features associated with the transient dynamics were numerically investigated. A jet flow was impulsively applied to the VR-12 airfoil using a boundary condition modeled as a COMPACT module in the wind tunnel experiments. A delayed detached-eddy simulation based on the Spalart–Allmaras turbulence model was conducted. Computational results indicated that the aerodynamic characteristics quickly varied in the early stage after jet initiation, and that the impact of the actuation on the flow behavior was gradually reduced through a larger time scale than the freestream convection. A detailed investigation was performed to assess relevant flow features, and two distinct flow characteristics associated with the transient dynamics were identified: reattachment and recirculation. Reattachment in the early stage after actuation yielded a high suction peak near the leading edge and rapidly enhanced the lift force. Recirculation in the later stage affected gradual variations in the aerodynamic forces and moment to the baseline flow via the generation of a low-pressure region on the suction side.