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Experimental investigation of flow and coherent properties of excited non-circular liquid jets
Author(s): Morsal Babayan, Pejman Tabatabaee-Hosseini, Negar E. Kandjani, Seyed Amir Tafrishi, M. Jafari, E. Esmaeilzadeh
Keywords: Non-circular Free jet, Liquid-gas instability, Axis-switching, Breakup length, Penetration length.
Non-circular jets are identified as an efficient passive flow-control technique that attracts many research topics. The main reasons for dissimilarity between circular and non-circular jets stem from the existence of twin-vortexes manipulating jet instability and production of droplets and satellites, as well. This investigation presents liquid-gas interfaces instabilities as an applicable motif in free-jet flows. We experiment different jet geometries within a gas ambient in order to study their hydrodynamic behavior. These studies give an appropriate perception about contributing forces that play essential roles in fluid instability. The illustrated work mainly focuses on the viscosity and surface tension variations as excitation techniques. These methods are vital to examine the key properties of non-circular jets such as breakup and decay length, axis-switching wavelength, and produced droplets and satellites important characteristics. First, the instability of charged liquid jets was investigated by considering the interaction between electric and inertial forces. Also, the viscosity effect was studied through its interaction with the inertial and surface tension forces. In each case, liquid jet instability for various nozzle geometries over a specific range of jet velocity is examined. The obtained results illustrate that the geometry of nozzle has an indisputable effect on jet instability. In addition, increment of $We$ number raises the breakup and decay length as well as the axis-switching wavelength. However, increasing the twin-vortex number, lengthens the breakup length but reduces the decay length and axis-switching wavelength.