Flow characteristics of two-dimensional impinging synthetic jets

We aimed to elucidate the behavior of impinging synthetic jets against the surface of a wall placed near the slot exit. Synthetic jets with various frequencies were used, and a rectangular body of finite length (target plate) was placed downstream of these jets. The flows were visualized by the smoke-wire method and numerical simulation, and the velocity distributions around the target plate were measured using a hot-wire anemometer. The flow fields of steady continuous jets and synthetic jets with unsteady characteristics were compared, and their flow characteristics were explored. We experimentally found that the flow field depends on the dimensionless target plate length and dimensionless frequency of the synthetic jet for a fixed distance from the slot to the target plate. Furthermore, at low frequencies, the behavior after impinging the target plate was similar to that observed for a continuous jet. Additionally, it has been confirmed that these results qualitatively agree with the numerical simulation results.