A Quick Review on Experimental, Computational, and Optimization Studies of Coherent Structures in Swirling Flow

Swirling jets are defined by a velocity component in the azimuthal direction (swirl). They can occur naturally, such as in tornadoes, or artificially, as in gas turbine combustors, swirl burners, etc. Two principal occurrences are observed when the swirl value exceeds a particular threshold: vortex breakdown (VB) and precessing vortex core (PVC). The emergence of a stagnation point in the jet, followed by a reverse flow zone, indicates vortex breakdown, whereas PVC arises after the onset of VB defined as the jet's precession about its geometrical axis. The coherent structures associated with PVC affect the performance of swirl flow thus it is crucial to examine and comprehend these phenomena. It is important for a researcher to become familiar with past investigations conducted on the relevant subject before beginning their research. The purpose of this study is to highlight recent experimental and Computational Fluid Dynamics, (CFD) work on coherent structures in swirling flow by different researchers. In addition, an overview of several optimization techniques such as Artificial Neural Network (ANN) is provided. The major purpose of this review is to discuss the potential of employing ANN in swirling flow along with making recommendations for future research.