A numerical study on the influence of cavity shape on synthetic jet performance

Highlights: • Experiments and numerical computations agree that the internal cavity shape of a synthetic jet actuator affects the performance of the jet at the nozzle exit. • Sharper nozzle-to-cavity geometric transition results in larger momentum flux at the nozzle exit. • Synthetic jet behavior, as it relates to cavity and nozzle geometry, is different to the behavior of a continuous jet through the same geometry. • From a computational perspective, the flow field within the cavity must be computed for accurate exit conditions. A comparison of numerical and experimental analysis of cavity shape influence on flow properties of a synthetic jet is presented. The goal is to highlight areas that are challenging to measure and to better understand the in-cavity flow and exit characteristics. In the examination of three cavities it is found that, in accordance with experiments, the cavity with the sharpest nozzle-to-cavity transition transmits the most momentum at the exit. The sharp transition within the cavity results in a stronger vortex, higher self-induced inward velocity, and ultimately more room for flow to exit the cavity during the expulsion phase. It is shown that the shape of the internal cavity plays an important role in the flow behavior at the nozzle exit. From a computational perspective, the results suggest that the flow field within the cavity must be computed to obtain accurate exit conditions for the synthetic jet.