Synthetic Jets in Cross-Flow. Part 2: Jets from Orifices of Different Geometry

摘要

The flow fields of synthetic jets in a cross-flow from orifices of different geometry are investigated. The geometries include a straight. a tapered, a pitched and a cluster of nine orifices, all having the same cross- sectional area through which the perturbation is discharged into the cross-flow. The 'strength' of the jet from the tapered orifice in comparison to that from the straight one is found to be only slightly enhanced. The flow field from the cluster of orifices, when viewed a few equivalent diameters downstream, is similar to that from the single orifice. However, the penetration is somewhat lower in the former case due to the increased mixing of the distributed jets with the cross-flow. The penetration for the pitched configuration is the lowest, as expected. The jet trajectories for the straight and pitched orifices are well represented by correlation equations available for steady jets-in-cross-flow. Distributions of streamwise velocity, vorticity as well as turbulence intensity are documented for various cases. In addition, distributions of phase-averaged velocity and vorticity for the cylindrical and the clustered orifices are presented providing an insight into the flow dynamics.