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Experimental investigation on the effect of non-circular ring tab on mixing characteristics of subsonic and underexpanded jets

  • Thanigaiarasu Subramanian EMAIL logo and Dhamodaran Kamalakannan
Published/Copyright: November 19, 2025
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International Journal of Turbo & Jet-Engines
From the journal International Journal of Turbo & Jet-Engines

Abstract

Mixing features and potential core reduction of the jet from nozzle exit may reduce aircraft noise and improve combustion characteristics and thrust vectoring. The mixing enhancement was achieved using a non-circular ring tab in which a single 6-side star ring tab (6SSRT) arrangement with strut is fixed at the nozzle exit instead of the conventional two-tab method. The 6SSRT design creates non-uniform and counter-rotating vortices that lead to improved mass entrainment characteristics, axis switching, and differential jet spread. For nozzle exit Mach values of 0.4, 0.6, and 0.8, axial and radial jet spread is compared to the free jet, with possible core reductions of 40 %, 60 %, and 91.67 %, respectively. Radial plots and Mach contours illustrate that 6SSRT jets decay faster than free jets and flow deviation from the nozzle axis. Experimental results show that 6SSRT promotes jet mixing and shortens the potential core to lower jet noise and thrust vectoring.

Keywords: axis switching; jet deflection; kelvin Helmholtz instability; mixing enhancement; potential core reduction; star ring tab
Corresponding author: Thanigaiarasu Subramanian, Department of Aerospace Engineering, MIT Campus, Anna University, 600044, Chennai, India, E-mail:

Nomenclature (SI Units)

M

Mach Number;

Mj

Mach Number at the nozzle exit;

Po

Settling chamber pressure (N/m2);

Patm

atmospheric pressure (N/m2);

X

Distance along the axial direction of the jet (mm);

Y

Distance along the radial (vertical) direction of the jet (mm);

Z

Distance along the radial (lateral) direction of the jet (mm);

γ

Specific heat ratio.

Acknowledgments

The authors sincerely thank Mr. Yadav, who worked on the circular solid tab, which provides insights into generating the ring tab for our study.

  1. Research ethics: Not applicable.

  2. Informed consent: Not applicable.

  3. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission. K. Dhamodaran: Methodology; Formal analysis, Data curation; Writing -Original draft; S. Thanigaiarasu: Formal analysis; Writing - Review & Editing; Visualization; Supervision.

  4. Use of Large Language Models, AI and Machine Learning Tools: Grammarly tool was used to correct the grammar and improve the clarity of the content.

  5. Conflict of interest: All other authors state no conflict of interest.

  6. Research funding: None declared.

  7. Data availability: Research data are not shared.

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Received: 2024-06-10
Accepted: 2025-10-30
Published Online: 2025-11-19

© 2025 Walter de Gruyter GmbH, Berlin/Boston

https://doi.org/10.1515/tjj-2024-0053
Keywords for this article
axis switching; jet deflection; kelvin Helmholtz instability; mixing enhancement; potential core reduction; star ring tab
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