Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/3484

Title

Coherent structure dynamics in jets from irregular shaped nozzles

Author(s)

Hart, James T.;  Naser, Jamal A.;  Witt, Peter J.

Abstract

Computational Fluid Dynamics was used to model spatially developing, initially laminar, gas jets issuing from nozzles of regular and irregular cross-section, using the Large Eddy Simulation (LES) technique. Nozzles were based on bluff jets used in tangentially fired lignite-burning furnaces. Validation of the LES based model was achieved by comparing predicted jet entrainment rates with published experimental and numerical data. Large-scale coherent turbulent structures including ring and braid vortices and other stream wise structures are predicted by the LES model. The shape of the ring vortices formed was found to directly relate to the nozzle geometry. Size and proximity of discontinuities in the vortex rings were observed to determine how strongly a vortex ring deforms, furthermore discontinuities in the ring curvature were found to alter the number of stream wise structures formed. Jets with only a single pair of braid vortices per side were predicted to spread along their axes while those with multiple braids spread more uniformly.

Publication type

Conference paper

Research centre

Swinburne University of Technology. Faculty of Engineering and Industrial Sciences

Source

Proceedings of the 15th Australasian Fluid Mechanics Conference, 13-17 December 2004, University of Sydney, NSW

Publication year

2004

Publisher

University of Sydney

Publisher URL

http://www.aeromech.usyd.edu.au/15afmc/proceedings/

Copyright

Copyright © The University of Sydney 2004

Peer reviewed