Swirl momentum control in vortex rings generated experimentally

Ortega-Chavez, Rigoberto; Gan, Lian; Gaskell, Phil

Abstract

Particle image velocimetry is used to study the control of swirl momentum, delivered through an orifice formed by a physically rotating tube of finite length, relevant to the evolution of vortex rings produced at a Reynolds number Re≈1000 based on the average discharge velocity, for swirl numbers S ∈[0, 1]. Experiments without discharge, reinforced with complimentary numerical predictions, reveal the presence of an intriguing secondary flow pattern in the rotating tube, preventing attainment of a solid-body-like swirl distribution. Nevertheless, it is found that fully established rings produced in this way, following discharge once conditions in the tube have reached a steady state, exhibit similar characteristics to rings formed by an otherwise solid-body rotating initial condition as explored computationally by Ortega-Chavez et al. (2023, J. Fluid Mech. 967,A16). Namely, opposite-signed vorticity forms due to vortex tilting, which subsequently interacts with the ring, promoting vorticity cancellation and vortex ring breakdown. A key feature of the experimental work is that partially established vortex rings, produced before a steadystate rotating tube condition is reached, show unique characteristics. Their creation, a short time after the onset of tube rotation: (i) facilitates more efficient delivery of swirl momentum to the vortex core area; (ii) maintains a low level of swirl in the ring bubble’s central region which would otherwise promote the formation of opposite-signed vorticity and vortex breakdown.

Citation

Ortega-Chavez, R., Gan, L., & Gaskell, P. (2025). Swirl momentum control in vortex rings generated experimentally. Journal of Fluid Mechanics, 1007, Article A20. https://doi.org/10.1017/jfm.2025.34

• Journal Article Type: Article
• Acceptance Date: Dec 24, 2024
• Online Publication Date: Mar 14, 2025
• Publication Date: Mar 25, 2025
• Deposit Date: Dec 26, 2024
• Publicly Available Date: Mar 19, 2025
• Journal: Journal of Fluid Mechanics
• Print ISSN: 0022-1120
• Electronic ISSN: 1469-7645
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Volume: 1007
• Article Number: A20
• DOI: https://doi.org/10.1017/jfm.2025.34
• Public URL: https://durham-repository.worktribe.com/output/3229698