Experimental investigation of the precessing vortex core in annular swirling jet flows in the transitional regime

In this paper, we study the flow structures and associated dynamics of an annular swirling jet in the transitional flow regime at Re = 520. In literature, studies on fully laminar or turbulent jets are plentiful, but detailed quantitative data for transitional jets are very scarce. Time-resolved stereoscopic particle image velocimetry measurements are employed to study the flow dynamics in combination with a spectral proper orthogonal...