Two semi-analytical approaches for solving condensation shocks in supersonic nozzle flows

Autor(es)

Bolanos-Acosta, A. F. ; Restrepo, J. C. ; Simoes-Moreira, J. R.

• Tipo de documento: Artigo Científico
• Fonte: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER; v. 173, p. 14-pg., 2021-03-29.

Resumo

The paper describes two methods for solving condensation shocks in steady-state quasi-one-dimensional flows. A single-fluid-model has been implemented by solving the algebraic form of compressible flow conservation equations, in conjunction with nucleation and droplet growth laws from gas-kinetic theory. The second method assumes the condensation shock problem as a flow discontinuity, the downstream state of the shock being defined as a weak-detonation, and determined from intersections on the Rayleigh and Hugoniot curves. Both approximations have been implemented with complex multi-parameter equations-of-state based on the Helmholtz free energy, taking into account the non-ideal gas flow behavior of steam and carbon dioxide. In order to reproduce operating conditions of engineering applications, where non-equilibrium condensation occurs such as steam turbines, injectors, supercritical carbon dioxide compressors and supersonic gas flow separators. Both gas-kinetic and flow discontinuity approaches have been tested for several nozzle geometries and results have been compared with low- and high-pressure experimental data of steam and carbon dioxide. The results show that both models are able to model properly the pressure recovery that occurs in supersonic condensing flows. It has been found a low deviation 4% from experimental data of steam, and deviations within 8 % were found for the carbon dioxide case. The average droplet radius size distribution obtained from the droplet growth model is in the same order of magnitude of that of reported by experimental data available in open literature. Finally both methods were implemented in a converging-diverging nozzle of a carbon dioxide ejector in order to explore the effects of the stagnation temperature and to determine conditions free of condensation. (C) 2021 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 14/50279-4 - Brasil Research Centre for Gas Innovation
• Beneficiário: Julio Romano Meneghini
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia