Non-equilibrium condensation of water vapour in supersonic flows with shock waves

Wen, Chuang; Karvounis, Nikolas; Walther, Jens Honore; Ding, Hongbing; Yang, Yan

Abstract

The fluid flow and heat and mass transfer in a supersonic separator are not 14 understood well due to the complicated interaction of the supersonic flow, swirling flow, 15 phase transition and shock waves. In the present study, we develop a wet steam model 16 to investigate the flow structure inside a supersonic separator with the coexistence of 17 non-equilibrium condensation and shock waves. A study of the effect of the inlet 18 subcooling and inlet saturation on the condensation behaviour is conducted to evaluate 19 the performance of the supersonic separation with a focus on the shock wave. The 20 numerical result shows that the degree of supersaturation of the water vapour can reach 21 a maximum value of 4.28 within the designed supersonic separator and generate a peak 22 nucleation rate of approximately 10 21 kg m-3 s-1. The occurrence of the shock wave 23 changes the equilibrium thermodynamic state, which leads to the re-evaporation of the 24 condensed droplet. Higher inlet subcooling and inlet saturation not only shift 25 downstream the position of the shock wave, but also induce an earlier condensation and 26 higher liquid fraction. For the present nozzle, when the inlet subcooling and inlet 27 saturation are about 34 K and 0.28 respectively, the shock wave intersects the region of 28 the intense nucleation process, the non-equilibrium condensation process is terminated 29 due to the increase of the pressure and temperature downstream the shock wave. 30 Stronger swirling flow results in non-uniform distribution of the static pressure and 31 decreases the nucleation rate of water vapour. The high swirling flow with a maximum 32 swirl velocity of 150 m/s weakens the liquid fraction by 25% compared to the no 33 swirling flow. This indicates that it is important to balance the swirling flow and 34 condensation process to achieve an efficient performance of the supersonic separator. 35

• Journal Article Type: Article
• Acceptance Date: Nov 24, 2019
• Online Publication Date: Dec 14, 2019
• Publication Date: 2020-03
• Deposit Date: Feb 21, 2020
• Publicly Available Date: Dec 15, 2021
• Journal: International Journal of Heat and Mass Transfer
• Print ISSN: 0017-9310
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 149
• Article Number: 119109
• DOI: https://doi.org/10.1016/j.ijheatmasstransfer.2019.119109
• Keywords: wet steam; condensing flow; supersonic flow; condensation; shock wave
• Public URL: https://nottingham-repository.worktribe.com/output/4005427
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0017931019323816
• Additional Information: This article is maintained by: Elsevier; Article Title: Non-equilibrium condensation of water vapour in supersonic flows with shock waves; Journal Title: International Journal of Heat and Mass Transfer; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.ijheatmasstransfer.2019.119109; Content Type: article; Copyright: © 2019 Elsevier Ltd. All rights reserved.