INFLUENCE OF VIBRATIONAL RELAXATION OF MOLECULES ON THE FLUCTUATION STRUCTURE AND STABILITY OF SUPERSONIC SF6 MICROJETS
I.S. Tsyryul’nikov, T.V. Poplavskaya, S.G. Mironov, S.V. Kirilovsky
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences (ITAM SB RAS), Novosibirsk, Russia
Keywords: supersonic nonisobaric jet, vibrational relaxation effect, stability
Abstract
A numerical study is performed to investigate the influence of vibrational excitation and relaxation of sulfur hexafluoride (SF6) molecules on the gas-dynamic structure and stability of high-speed microjets issuing from axisymmetric sonic micronozzles with diameters ranging from 10 to 110 μm. Direct numerical simulation of the gas flow is conducted by solving the unsteady three-dimensional Navier-Stokes equations using a two-temperature model for relaxing flows. The study is carried out over a wide range of Reynolds numbers determined by the micronozzle diameter. The influence of vibrational relaxation of gas molecules on the mode composition and spectral characteristics of disturbances, as well as on the length of the laminar region of the microjets, is observed.
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