Two approximations for solving non-equilibrium condensation shocks in supersonic nozzle flows.

• Autor(a) principal: Bolaños Acosta, Andres Felipe
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/3/3150/tde-04052023-083246/
• topic: Carbon dioxide; Condensação; Condensation shocks; Dióxido de carbono; Escoamento compressível; Gás real; Real gas; Steam; Supersonic nozzle flows; Vapor d'água

Non-equilibrium condensation occurs in engineering applications such as steam turbines, injectors, carbon dioxide supercritical compressors and supersonic gas flow separators. Consequently, any model able to characterize such a phenomenon is pursued in the field. This Masters dissertation describes two approximations for solving condensation shocks in supersonic nozzle flows. A gas-kinetic model has been developed based on a Single Fluid Model approximation, which consists of coupling nucleation and droplet growth concepts to the solution of algebraic conservation equations for compressible flow. The second method assumes the phase transition as a flow discontinuity, the jump conditions across the condensation shock are determined from intersections on Rayleigh and Hugoniot curves. Both methods have been implemented assuming steady-state in a quasi-one-dimensional flow model, and using cubic and complex multi-parameter equations-of-state in order to reproduce the non-ideal gas flow behavior of steam and carbon dioxide. Several simulations were performed in different nozzle geometries and flow conditions. The results shows that the weak detonation state from the discontinuity model, and the implemented gas-kinetic approximation estimate with accuracy the pressure recovery that occurs in condensing nozzle flows. It has been found that the predicted pressure expansion lines are in agreement with experimental data for steam, and discrepancies within 8% were found for the carbon dioxide case. The estimated average droplet radius size distribution presents the order of magnitude of the experimental values reported by the literature.