The relationship between the nucleation process and boundary conditions on non-equilibrium condensing flow based on the modified model

The aim of this work is to investigate the relationship between the nucleation process and boundary conditions on non-equilibrium condensing flow based on the modified model. Firstly, a modified model is developed to predict the non-equilibrium condensation flow. The modified model is validated in a nozzle and stator cascade, which shows a greater agreement with the experimental data compared with original model. Secondly, the influence of inlet steam superheat degree on the nucleation process is investigated. The results show that: 1. The inlet steam superheat degree just plays an important role in the nucleation zone and the location of nucleation beginning. 2. The steam superheat degree has no effect on the minimum supercooling degree required for nucleation, which is about 17 K. It should be related to the property of vapor. Thirdly, the influence of the steam expansion rate on the nucleation process is studied. The results show that with the increment of the vapor expansion rate, the pressure rise becomes obvious, but no matter how the vapor expansion rate change, the minimum supercooling degree required for nucleation keeps constant, which is about 17 K. At last, the non-equilibrium condensation flow is investigated numerically in three-dimensional cascade. The results show that with the span increasing, the expansion rate gradually decreases and the nucleation rate decreases but the nucleation zone increases. Besides, the liquid mass fraction reduces with the span increasing. (C) 2019 Elsevier Ltd. All rights reserved.