Unsteady Forcing of a Post-stall Flow Over a NACA0012 Airfoil by a Surface DBD Actuator

摘要

The present study deals with the enhancement of a NACA0012 aerodynamic airfoil performance by using a thin DBD actuator to control flow separation occurring around the leading-edge. The post-stall separated flow over an airfoil is characterized at least by a shear layer emitted from the leading edge that corresponds to convective process instability and a wake flow corresponding to a global instability behavior, related to a vortex shedding. According to the forcing frequencies, different modifications of the shear layer rollup and wake vortex shedding can usually be observed. This study highlights the actuator effects by unsteady actuation with forcing frequencies selected according to the natural frequency of the wake vortex shedding. Mean aerodynamic force measurements, PIV and hot-wire anemometry in the vicinity of the shear layer and in the far wake were performed to characterize the benefits of the control. For a deep post-stall airflow, results show that forcing frequencies closer to the wake vortex shedding frequency lead to achieve a high increase in lift.