Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/84045
Title: Near-field dynamics of parallel twin jets in cross-flow
Authors: Zang, Bin
New, Tze How
Keywords: Laser Induced Fluorescence
Rotating Flows
Issue Date: 2017
Source: Zang, B., & New, T. H. (2017). Near-field dynamics of parallel twin jets in cross-flow. Physics of Fluids, 29(3), 035103-.
Series/Report no.: Physics of Fluids
Abstract: The present study examines the near-field flow developments and dynamics of parallel twin jets in cross-flow (TJICF) configured with jet-to-jet separation distances of 1.5 to 3 jet diameters (D) and velocity ratios of 2, 4, and 6. Both laser-induced fluorescence and particle-image velocimetry measurements were made along the streamwise and cross-stream planes in order to investigate the effects of the separation distance and velocity ratio upon the deflected jet and the formation of counter-rotating vortex-pairs (CVPs) within the near-field region. Results show that each jet in the parallel TJICF configuration attains higher cross-flow entrainment and produces greater jet half-widths than a single jet in cross-flow (SJICF). Moreover, as the separation distance decreases to 1.5D, the twin jets interact closer to the jet exit such that organized leading-edge and lee-side vortices are present along the symmetry plane. Cross-stream results indicate that the pair of inner vortices associated with the two resulting CVPs is being induced to move towards each other along the symmetry plane, where their opposite-signed vorticities annihilate with each other eventually. As such, the vorticity transition from two CVPs into a resulting single CVP takes place quickly within the near-field region when the separation distance is sufficiently small. Streamwise circulation decays determined for parallel TJICF show that their circulations increase moderately when the two CVPs begin to interact with each other. Further examination into the Reynolds shear stresses indicates that there exists substantial flow shear stress as the pair of inner vortices interacts, which yields higher entrainment level of the cross-flow fluid in regions adjacent to the symmetry plane. As a result, the near-field jet trajectories for each jet in the parallel TJICF are always lower than that of the corresponding SJICF when the separation distance is small, regardless of the velocity ratios.
URI: https://hdl.handle.net/10356/84045
http://hdl.handle.net/10220/42906
ISSN: 1070-6631
DOI: 10.1063/1.4978856
Schools: School of Mechanical and Aerospace Engineering 
Rights: © 2017 American Institute of Physics. This paper was published in Physics of Fluids and is made available as an electronic reprint (preprint) with permission of American Institute of Physics. The published version is available at: [http://dx.doi.org/10.1063/1.4978856]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:MAE Journal Articles

Files in This Item:
File Description SizeFormat 
Near-field dynamics of parallel twin jets in cross-flow.pdf27.53 MBAdobe PDFThumbnail
View/Open

SCOPUSTM   
Citations 20

23
Updated on Jun 4, 2024

Web of ScienceTM
Citations 20

19
Updated on Oct 29, 2023

Page view(s)

389
Updated on Jun 15, 2024

Download(s) 50

136
Updated on Jun 15, 2024

Google ScholarTM

Check

Altmetric


Plumx

Items in DR-NTU are protected by copyright, with all rights reserved, unless otherwise indicated.