Kulikov, D. V.3; Mikkelsen, Robert Flemming1; Naumov, Igor1; Okulov, Valery1
1 Department of Wind Energy, Technical University of Denmark2 Fluid Mechanics, Department of Wind Energy, Technical University of Denmark3 Russian Academy of Sciences
We report for the first time on the possible formation of regions with counterflow (bubble-mode vortex breakdown or explosion) at the center of strongly swirling flow generated by a rotating endwall in a large-aspect-ratio cylindrical cavity filled with a liquid medium. Previously, the possibility of bubble-mode breakdown was studied in detail for cylindrical cavities of moderate aspect ratio (length to radius ratios up to H/R ∼ 3.5), while flows in large-aspect-ratio cylinders were only associated with regimes of self-organized helical vortex multiplets. In the present study, a regime with nonstationary bubble-mode vortex breakdown has been observed in a cylindrical cavity with H/R = 4.5.
Technical Physics Letters, 2014, Vol 40, Issue 2, p. 181-184