Computer analysis of condensation in highly expanded flows.

Abstract

The equations of spontaneous nucleation theory are combined with the steady one-dimensional diabatic flow equations for a digital computer solution of the expansion of a pure vapor in a two-dimensional nozzle. The results indicate that the solution gives a reasonable prediction of the condensation in highly expanded flows. Theoretical predictions of condensation, primarily in the flow of nitrogen, with some in copper and zinc vapors are obtained. The effects of variations in specific heat, latent heat, and accommodation coefficient show only minor effects on the condensation compared to the effect of a variation in surface tension. The solution critically depends on the value of surface tension. The theoretical prediction of condensation of nitrogen compares well with experimental results. The degree of supersaturation of the flow increases with an increased rate of expansion, and, for some initial conditions, condensation-free flow is obtainable. Nomenclature A = nozzle cross-sectional area A* = throat area B, C = saturation curve constants for Inpoo = B — C/T Cp = specific heat at constant pressure g = fraction of mixture, by mass, which is in condensed phase