Condensation processes in turbulent non-isothermal free steam jet in air

A method based on introduction of a presumed joint probability density function of the vapour mass fraction and enthalpy of the two-phase mixture is proposed for finding the average rate of condensation, including nucleation and vapour deposition on the liquid surface. The presumed joint pdf carrier consists of two branches: one for pure mixing and the other for the saturated vapour. The method is illustrated with numerical simulations of condensation in a free turbulent jet of saturated steam issuing into cold air and assessed against the experimental data collected for such a jet using a Phase Doppler Anemometry system. It is shown that relatively large size of drops observed in condensing water vapour jets may be explained by simultaneous action of homogeneous condensation and droplet collisions while inhomogeneous condensation does not seem to play any significant role.