FLOW CHARACTERISTICS AND VELOCITY FIELDS OF SWIRLING DOUBLE-CONCENTRIC JETS AT HIGH CENTRAL JET REYNOLDS NUMBERS

Authors

Minh Duc Le, Department of Mechanical Engineering, National Taiwan University of Scienceand Technology, Taipei, Taiwan, R.O.CFaculty of Transportation Mechanical Engineering, The University of DanangUniversity of Science and Technology, Nguyen Luong Bang, Danang, Vietnam
Ching Min Hsu, Department of Mechanical Design Engineering, National Formosa University, Yunlin, Taiwan, R.O.C.
Rong Fung Huang, Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, R.O.C

Abstract

The flow characteristics and velocity fields of swirling doubleconcentric jets at a high central jet Reynolds number were studied. The central jet Reynolds numbers varied from 700 < Rec < 1000. The flow behaviors of the swirling double-concentric jets were observed using a laser light sheet assisted by a smoke-wire flow visualization technique. The time-averaged velocity vectors and streamlines, normalized velocity contours, fluctuation intensity contours, and vorticity contours were carried out using particle image velocimeter (PIV). Two characteristic flow modes are classified: the central jet-dominated radial flow occurs at a low annular jet Reynolds number while the high-turbulence swirling wake appears at a high annular jet Reynolds number. The flow feature of the central jet-dominated radial flow presents a wideopen shear layer because of the effect of a high-speed deflected central jet. A large dual-ring vortex in the wake and two pairs of vortices in the gap between the control disk and primary disk in the high-turbulence swirling wake mode appear. The turbulence intensity in the high-turbulence swirling wake were significantly larger than those in the central jet-dominated radial flow.

Recommended Citation

Le, Minh Duc; Hsu, Ching Min; and Huang, Rong Fung (2018) "FLOW CHARACTERISTICS AND VELOCITY FIELDS OF SWIRLING DOUBLE-CONCENTRIC JETS AT HIGH CENTRAL JET REYNOLDS NUMBERS," Journal of Marine Science and Technology: Vol. 26: Iss. 5, Article 2.
DOI: 10.6119/JMST.201810_26(5).0002
Available at: https://jmstt.ntou.edu.tw/journal/vol26/iss5/2