Non-equilibrium condensation process of water vapor in moist air expansion through a sonic nozzle

• Gas–liquid two-phase flow k–ε turbulence models for vapor condensation were built.
• The models have been validated by the experimental data and analytical results.
• The effects of vapor condensation on flow rate of a sonic nozzle were obtained.
• Experiments on periodic, unsteady condensation flow in the sonic nozzle were reported.

Non-equilibrium vapor condensation phenomenon through a sonic nozzle is very complicated and closely related to the flow measurement of the sonic nozzle. The gas–liquid two-phase flow Eulerian models for homogeneous and heterogeneous nucleation of moist gas in transonic nozzle flow were built to investigate the effect of vapor condensation on the mass flow rate of the sonic nozzle. Grid independence was achieved by using a solution-adaptive refinement. The CFD models were carefully validated by published experimental data and analytical results. It was shown that the flow rate of the sonic nozzle is affected by both homogeneous and heterogeneous nucleation. In comparison with the experimental data, the effects of vapor condensation on the mass flow rate of the sonic nozzle were obtained. Besides, experiments on periodic, unsteady condensation flow in the sonic nozzle were also reported. This unsteady flow will also affect the flow rate of the sonic nozzle. The results of experiments accorded well with simulations and semi-empirical formula. All the results can be used to further analyze the effect of unsteady flow induced by vapor condensation on the flow rate of the sonic nozzle.