K-1302 Coherent Structure in a Two-Dimensional Jet Excited by Wake of a Cylinder Installed in Nozzle Contraction

Abstract

It is possible to control the spread of a plane jet passively by the vortices from a two-dimensional cylinder installed in the nozzle contraction. In this study, the wake characteristics of a cylinder and the coherent structure of a jet by this passive control method were examined. In wide range of strouhal number Sto based on vortex shedding frequency (fv) and jet exit velocity, the spreads of the jet were found to be suppressed. On the other hand, hi particular cases of Sto being 0.08-0.10, the spread of the jet was remarkably enhanced associated with distinctive peaks of spectrum which arose from the deformation of the vortices by flow contraction in nozzle.