Educing coherent eddy structures in air curtain systems

• Published in: Chemical engineering and processing 2008-03, Vol.47 (3), p.435-448
• Main Authors: Loubière, Karine, Pavageau, Michel
• Format: Article
• Language: English
• Subjects: Ambiance separation; Applied sciences; Chemical engineering; Engineering Sciences; Exact sciences and technology; Flow pattern recognition; Hydrodynamics of contact apparatus; Impinging jets; Particle image velocimetry; Smoke and heat confining; Turbulent plane jets
• ISSN: 0255-2701; 1873-3204
• DOI: 10.1016/j.cep.2007.01.014

The work reported here comes within a broader research program dealing with volume separation or confining by means of air curtains (plane air jets). The process is studied experimentally by particle image velocimetry (PIV). In this paper, the emphasis is put on the flow structure in the impingement region of such jet systems insofar as it is where transfers occur preferentially. More precisely, a vortex eduction method was implemented under the Matlab environment enabling both the automatic detection of 2D coherent patterns embedded in PIV velocity vector maps, and a statistical analysis of the topological and energy features of these structures. First, the approach is explained in detail. The second part of this paper is devoted to its application in the case of plane turbulent impinging simple- and twin-jets for various jet exit velocities. Results about the size, the shape, the spatial distribution and the energy content of the detected vortices are provided. Although many questions still remain open, new insights into the fashion these structures might form, organize and evolve are given providing an original picture of the plane turbulent impinging jet.