In this study, the coherent structure dynamics and entrainment capability of elliptical jets emitted from an elliptical nozzle with aspect ratio (AR) values of 1 (i.e., a circular jet), 2, and 4 at a fixed Reynolds number of 3,000 were experimentally characterized by flow reconstruction using tomographic particle image velocimetry and modal decomposition using the spectral proper orthogonal decomposition method. Statistical analysis indicated that the elliptical synthetic jet had a greater entrainment rate and momentum flux than the circular jet. The temporal dynamics of the coherent structure showed that all the jets emitted from the elliptical nozzle at AR = 1 (i.e., a circular jet), 2, and 4 had a dominant frequency at Strouhal number (St) = 0.39, representing the leading Kelvin–Helmholtz (K-H) vortex ring in each jet. The frequency of the trailing vortex was also at St = 0.39 at AR = 1 and 2, whereas that at AR= 4 was at St = 0.70. It was found that vortex ring pairing and merging, as well as axis switching, are common in elliptical jets. When AR was 4, there was also a large-scale single vortex ring between the two merged vortex rings, this large-scale single vortex alone underwent axis transformation and breakage. The merger always occurred in the major plane in elliptical jets because in the major plane, the leading and trailing vortices approached each other as a result of self-induction and mutual induction. The entrainment rate was strongly correlated with the K-H vortex ring dynamics in circular jets and weakly correlated with the K–H vortex ring passing in elliptical jets. The entrainment appeared in the upstream part of the K-H vortex ring structures in circular jets, whereas it was enhanced in the axis-switching region in elliptical jets. An analysis of the contribution of each mode to mass entrainment showed that the entrainment rate of the elliptical nozzle was better than that of the circular nozzle, mainly because many streamwise vortices were generated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.