Characteristics of Small-Scale Synthetic Jets — Numerical Investigation

Abstract

In synthetic jet actuators with an orifice diameter typically less than 1 mm (termed as small-scale synthetic jet actuators), the compressibility and viscosity effects often become significant causing them behave differently from large-scale synthetic jets. In this paper, a numerical study of the synthetic jet from an orifice diameter of 0.5 mm is undertaken and the results are compared with the synthetic jet from an orifice diameter of 5 mm. The results reveal that, given the same dimensionless parameters L and Re _L , the appearance and circulation of vortex rings produced from synthetic jets of different scales are identical in the near field. It is also found that although the linear relationships between (L and Re _L ) and actuator operating conditions observed for large-scale synthetic jets are no longer valid for small-scale synthetic jets, the linear relationships between the dimensionless jet performance parameters and (L and Re _L ) still exist. This finding is very useful to support the development of low-dimensional predictions models.