Vibrational excitation and bifurcation of a round jet at low Reynolds numbers
A.K. Shevchenko, S.N. Yakovenko
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: round jet, vibrational excitation, jet bifurcation, Strouhal number, expansion angle, numerical experiments
Abstract
This paper presents the results of numerical simulation of a submerged jet leaving an orifice of diameter D with velocity U, when the nozzle is subjected to mechanical oscillations (vibrations) of frequency ƒ. Vibrational excitation leads to jet bifurcation at Reynolds number Re = DU/ν>50 in wide ranges of oscillation amplitude Z0, Strouhal number St = ƒD/U , and it is similar to acoustic forcing. The obtained estimates of the characteristic jet thickness and its expansion angle α performed to study the influence of Z0, Re, and St parameters allow identification of the optimal values Stopt of the Strouhal number, at which the splitting process is most pronounced. The previously noted effect of an increase in angle α with an increase in the excitation amplitude and saturation after some threshold values of amplitude Z0 are confirmed. These results also indicate that with a decrease in Re, the threshold amplitude (above which saturation in a occurs) increases, and the maximum possible values of a drop significantly. The influence of Re on the optimal Strouhal number was found: with a decrease in Re from 3000 to 100, the Stopt values drop significantly.
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