Library Subscription: Guest

ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

HEAT AND MOMENTUM TRANSFER BY VORTEX IN MIXING LAYER

Get access (open in a dialog) DOI: 10.1615/IHTC11.890
pages 213-217

Abstract

Experiments were performed on the heat-and momentum transfer by vortices in a free mixing layer. A two-dimensional mixing layer was generated in-between two parallel air streams of different velocities and temperatures. Coherent vortices of natural frequency were excited by acoustic waves. Two-components LDA and thermoanemometer were applied to measure the phase-locked fields of velocity vectors and temperature. Time- and ensemble-averaged statistics and coefficients of turbulent transfer of the first generation vortex were calculated. The Reynolds number referred to the thickness of the mixing layer was 3 500.
The experiments suggested that momentum and heat transfer by a vortex is closely related to the orientation of vortex axis. The subharmonic fluctuations of the mixing layer gives rise to variable inclinations of the vortex axis and fluid may be either entrained into the vortex, or discharged from it. Heat transfer by entrainment of the fluid into the vortex with the main frequency dominates on the fast side of the flow, while the transfer by the second subharmonic frequency prevails at the slow side of the flow.