Shear Excitation Effects on Coaxial Swirling Jets

The present study explores the swirl jet characteristics and the possibility of using artificial means for the control of shear layers with the application as swirl jet mixing. The numerical analysis is performed to investigate the helical-lobed excitation effects. The computational results are compared with a baseline at various conditions. In general, axisymmetric swirling jets are unstable in the near field to all the excitation cases examined. It is shown that the overall response of the swirling jet to excitation is dependent on the helical mode number. Excitation at helical perturbations simultaneously affects the flow property distributions in the vortex core and the shear layer at the jet periphery. Especially preferred helical mode is considered as the effective way of mixing enhancement for swirling jets.