Simulations for Turbine Design Considering Real Gas Effects with OpenFOAM

Lay, Daniel (2013). Simulations for Turbine Design Considering Real Gas Effects with OpenFOAM Honours Thesis, School of Engineering, The University of Queensland.

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Author Lay, Daniel
Thesis Title Simulations for Turbine Design Considering Real Gas Effects with OpenFOAM
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2013
Thesis type Honours Thesis
Supervisor Paul Petrie-Repar
Total pages 70
Language eng
Subjects 0913 Mechanical Engineering
Formatted abstract
Concentrated solar thermal power systems have experienced a recent surge in interest. The use of supercritical carbon dioxide as a working fluid in these systems leads to considerable improvements in eciency and oers a number of other advantages when compared to working  fluids such as synthetic oil. However, operation in the supercritical
region leads to large deviations from ideal gas behaviour, hindering the design of supercritical turbomachinery. In such regions, real gas equations of state may be used for higher levels of accuracy.

This thesis aims to develop, and document, the implementation of a real gas equation of state in the free and open source Computational Fluid Dynamics (CFD) package OpenFOAM for use with supercritical carbon dioxide. No standard solvers currently exist within OpenFOAM that are capable of doing this. This study is also signicant in that
the thermophysical property structure and changes required to move from ideal gas to real gas models has not been made clear in OpenFOAM documentation.

This was achieved by the development of a simple nozzle test case, where a known analytical solution exists, followed by validation of developed models against known analytical solutions. A comprehensive grid dependency study was performed on the nozzle test case to ensure good computational eciency. The OpenFOAM thermophysical property
structure has been documented, and the changes needed to implement a real gas equation of state identied. Furthermore, regions where carbon dioxide, in the context of turbomachinery applications, experiences real gas eects, have been identied. The use of a compressibility factor equation of state by Lee and Kesler was found to be accurate, though an implementation in OpenFOAM was not achieved. For conditions nearer the critical point, more accurate equations of state are required. The Span and Wagner equation of state is one such equation.

Keyword Real Gas Effects

Document type: Thesis
Collection: UQ Theses (non-RHD) - UQ staff and students only
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Created: Thu, 03 Dec 2015, 13:32:38 EST by Asma Asrar Qureshi on behalf of Scholarly Communication and Digitisation Service