Characteristics of the precessing vortex core in the isothermal model of a radial type burner
E.Yu. Gorelikov1,2, I.V. Litvinov1,2, D.A. Suslov1,2, M.A. Tsoy1, S.I. Shtork1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: swirl flows, Particle Image Velocimetry (PIV), Proper Orthogonal Decomposition (POD)
Abstract
Experimental data on reconstruction of the spatial structure of a swirl jet in a burner model are presented. An isothermal case of free jet mixing with ambient air at various levels of flow swirl is considered. The high-swirl flows under study are accompanied by the collapse of the vortex core and intense coherent flow pulsations associated with large-scale vortex structures. Experimental data on distributions of axial and tangential velocities were obtained by Particle Image Velocimetry (PIV). The contribution of coherent flow fluctuations to turbulent transport is estimated based on the Proper Orthogonal Decomposition (POD). The frequency of periodic pressure pulsations was measured using acoustic sensors. The frequency of the precessing vortex core (PVC) and the corresponding velocity distributions were measured at a fixed Reynolds number (16500). A nonmonotonic dependence of the Strouhal number on the flow swirl was obtained. The spatial vortex structure was visualized under isothermal conditions. Using POD analysis, it was shown that with an increase in swirl, the precession radius and the pitch of the helical structure of the PVC increase.
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