Vortex Behavior of Pulsating Jets from a Rectangular Nozzle

This paper describes an experimental study on the vortex formation of a pulsating jet issuing from a rectangular nozzle of an aspect ratio of 5 which has a short parallel section upstream of the jet exit. Visualization with hydrogen bubble method reveals three-dimensional vortex nature. It was confirmed that vortices which originate from short sides of the nozzle flow downstream faster than vortices from long sides and shift into the jet axis. On the other hand the vortices from the long sides move away from the jet axis and downstream bend at their middle with the edges of the vortices going ahead. The three-dimensional vortex deformation that the major and the minor axis of the vortex ring are switched was confirmed further downstream.