Study of Non-Equilibrium Condensation in a Supersonic Jet

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1. Experimental studies of argon freejets with condensation.1) Freejet flow-fields were visualized utilizing laser Rayleigh scattering from condensates. From analysis of the visualized jets influences of condensation on the jet structure were examined; the Mach disk moves downstream and the barrel shock expands as a result of condensation. Stronger scattering was observed in a region between the barrel shock and the jet boundary than in the jet core.2) Strength of the Rayleigh scattering was measured along the jet axis. Changes of an average number of atoms in a cluster, J, were obtained from the measured intensity using numerical results of the condensation mass ratio. The value of J reaches 100 - 6000 depending on the stagnation condition. These values agree with those measured by a more direct method in a cluster beam.2. Numerical simulation of a freejet with non-equilibrium condensation.1) A method of numerical simulation of a freejet with condensation was established. For the condensation the classical nucleation theory was used.2) The method was extended to a case of a stochastic nucleation process. Numerical results show that the macroscopic flow properties are almost independent of unkown properties concerning with small clusters, but microscopic ones like values of J depends strongly on these values. By comparing parametric studies using this numerical method with experimental observation these parameters can be determined and hence the non-equilibrium condensation processe in a supersonic jet will become more clear.