Effects of homogeneous condensation in compressible flows: Ludwieg-tube experiments and simulations

X. Luo, G. Lamanna, A.P.C. Holten, M.E.H. Dongen, van

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    Abstract

    Effects of homogeneous nucleation and subsequent droplet growth in compressible flows in humid nitrogen are investigated numerically and exptl. A Ludwieg tube is employed to produce expansion flows. Corresponding to different configurations, three types of expt. are carried out in such a tube. First, the phase transition in a strong unsteady expansion wave is investigated to demonstrate the mutual interaction between the unsteady flow and the condensation process and also the formation of condensation-induced shock waves. The role of condensation-induced shocks in the gradual transition from a frozen initial structure to an equil. structure is explained. Second, the condensing flow in a slender supersonic nozzle G2 is considered. Particular attention is given to condensation-induced oscillations and to the transition from sym. mode-1 oscillations to asym. mode-2 oscillations in a starting nozzle flow, as first obsd. by Adam & Schnerr. The transition is also found numerically, but the amplitude, frequency and transition time are not yet well predicted. Third, a sharp-edged obstacle is placed in the tube to generate a starting vortex. Condensation in the vortex is found. Owing to the release of latent heat of condensation, an increase in the pressure and temp. in the vortex core is obsd. Condensation-induced shock waves are found, for a sufficiently high initial satn. ratio, which interact with the starting vortex, resulting in a very complex flow. As time proceeds, a subsonic or transonic free jet is formed downstream of the sharp-edged obstacle, which becomes oscillatory for a relatively high main-flow velocity and for a sufficiently high humidity. [on SciFinder (R)]
    Original languageEnglish
    Pages (from-to)339-366
    Number of pages28
    JournalJournal of Fluid Mechanics
    Volume572
    Issue number1
    DOIs
    Publication statusPublished - 2007

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