Effects of multijet coupling on propulsive performance in underwater pulsed jets
Name
PhysRevFluids.1.034501.pdf
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Author(s)
Athanassiadis, Athanasios G.
Hart, Douglas
Date Issued
July 2016
Journal
Physical Review Fluids
Publisher
American Physical Society (APS)
Citation
Athanassiadis, Athanasios G., and Douglas P. Hart. “Effects of Multijet Coupling on Propulsive Performance in Underwater Pulsed Jets.” Physical Review Fluids, vol. 1, no. 3, July 2016. © 2016 American Physical Society
Version
Final published version
Abstract
Despite the importance of pulsed jets for underwater propulsion, the effect of multiple-jet interactions remains poorly understood. We experimentally investigate how interactions between parallel jets in a pulsed-jet thruster affect the thruster's propulsive performance. Using high-speed fluorescence imaging, we investigate the mutual influence of two pulsed jets under conditions relevant to low-speed maneuvering in a vehicle (Re ≈ 350, L/D ≤ 2). Thrust production and propulsive efficiency are evaluated for different nozzle spacings using a new force estimation technique based on the fluorescence data. This analysis reveals that compared to noninteracting jets, the efficiency and thrust generated by the pair of interacting jets can fall by as much as 10% when the jets are brought into close proximity. Empirically, the thrust T falls off with the nondimensional jet spacing [~ over Δ] as T = T[bar over ∞](1 − Co[~ over Δ][superscript −6]) for a thrust coupling coefficient Co = 2.04 ± 0.11. Finally, we predict this dependence of thrust on spacing using a model that relates the thrust and efficiency drop to streamline curvature and vortex induction at the nozzles.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PHYSREVFLUIDS.1.034501
