A Study on the Coanda Effect and the Thrust Characteristics of Synthetic Jets

Although there have recently been various studies on synthetic jets, many issues remain to be clarified, including details of the structure, Coanda effect and thrust characteristics. The present study clarifies some fundamental flow characteristics of synthetic jets near a rigid boundary by experiments and numerical simulations. In addition, a thruster model using the Coanda effect of synthetic jets is proposed and thrust characteristics are evaluated. As the main results, the flow of a synthetic jet near a rigid boundary is visualized and the trajectory of a vortex pair is demonstrated. It is confirmed that the flow patterns of the synthetic jets near a rigid boundary depend on H/b₀ (offset ratio, normalized step height). The behavior of the asymmetric synthetic jets caused by the presence of the rigid wall was observed experimentally and the results were compared with numerical data. Furthermore, typical flow patterns around the proposed synthetic jet thruster and its thrust characteristics curves are shown.