An experimental analysis of the dominant instabilities in the initial merging region of two coaxial jets is presented. Different inner/outer jet velocity pairs U_i,U_o have been tested in order to investigate the effect of both velocity ratio r_u=~U_o/U_i and Reynolds number in the instability characteristics. Three main instabilities have emerged depending on the velocity ratio. For r_u<0.75 the coaxial jets dynamic is driven by the inner shear layer. For r_u>1.6 the outer shear layer dominates the near field vortex dynamics, while for velocity ratios nearly unitary the vortex shedding behind the separating wall imposes its own dynamics.
Main Instabilities of Coaxial Jets / A. Segalini; A. Talamelli. - STAMPA. - (2012), pp. 139-142. (Intervento presentato al convegno Progress in turbulence and wind energy IV : Proceedings of the iTi Conference in Turbulence 2010 tenutosi a Bertinoro, Forlì Cesena (Italy) nel 2010) [10.1007/978-3-642-28968-2_29].
Main Instabilities of Coaxial Jets
TALAMELLI, ALESSANDRO
2012
Abstract
An experimental analysis of the dominant instabilities in the initial merging region of two coaxial jets is presented. Different inner/outer jet velocity pairs U_i,U_o have been tested in order to investigate the effect of both velocity ratio r_u=~U_o/U_i and Reynolds number in the instability characteristics. Three main instabilities have emerged depending on the velocity ratio. For r_u<0.75 the coaxial jets dynamic is driven by the inner shear layer. For r_u>1.6 the outer shear layer dominates the near field vortex dynamics, while for velocity ratios nearly unitary the vortex shedding behind the separating wall imposes its own dynamics.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
