Numerical sensitivity study on nucleation bulk tension factor of non-equilibrium condensation model

The spontaneous condensation process of steam has obvious non-equilibrium characteristics, the accurate prediction of which is challenging. In this work, the nucleation bulk tension factor (NBTF) is used to modify the droplet surface tension for improving the accuracy in the calculation of the steam condensation flow. The non-equilibrium condensation processes in two nozzles are numerically simulated using a surface tension model with NBTF. The influence of NBTF on the simulation accuracy of the steam spontaneous condensation flow is analyzed. The correlation among the optimal value of NBTF, steam expansion rate and inlet parameters is emphatically studied. The obtained results show that the optimum value of NBTF is not sensitive to the change in the steam expansion rate under the same working conditions. It has no significant correlation with the total inlet temperature, but has a significant positive correlation with the total inlet pressure. Based on the numerical results, a cubic polynomial regression model between the optimal NBTF and total inlet pressure is obtained, the reliability of which is further verified by numerical calculation of a wet steam two-phase flow in the Bakhtar plane cascade. These results can provide a reference for determination of the optimum NBTF in wet steam condensation nucleation models.