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Title: | Comparison of CFD predictions of supercritical carbon dioxide axial flow turbines using a number of turbulence models |
Authors: | AbdElDayem, AER White, MT Sayma, AI |
Keywords: | axial turbines;loss estimation;turbulence modelling;supercritical CO2 |
Issue Date: | 16-Sep-2021 |
Publisher: | The American Society of Mechanical Engineers |
Citation: | AbdElDayem, A., White, M.T. and Sayma, A.I. (2021) 'Comparison of CFD predictions of supercritical carbon dioxide axial flow turbines using a number of turbulence models', Proceedings of the ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. Volume 10: Supercritical CO2. Virtual, Online. 7–11 June, V010T30A010, pp. 1 - 15. doi: 10.1115/GT2021-58883. |
Abstract: | A detailed loss assessment of an axial turbine stage operating with a supercritical carbon dioxide (sCO2) based mixture, namely titanium tetrachloride (CO2-TiCl4 85-15%), is presented. To assess aerodynamic losses, computational fluid dynamics (CFD) simulations are conducted using a geometry generated using mean-line design equations which is part of the work delivered to the SCARABEUS project [1]. The CFD simulations are 3D steady state and employ a number of turbulence models to investigate various aerodynamic loss mechanisms. Two categories of turbulence models are used: Eddy Viscosity and Reynold’s Stress models (RSM). The Eddy Viscosity models are the k-ε, k-ε RNG, k-ω, k-ω SST and k-ω Generalized while the RSM models are BSL, LRR, w-RSM and k-ε EARSM. The comparison between different turbulence models showed minor deviations in mass-flow rate, power output and blade loading while significant deviations appear in the loss coefficients and the degree of reaction. It is noted that the k-ε model gives the highest loss coefficients and the lowest isentropic efficiencies while most of the RSM models indicate higher efficiencies and lower loss coefficients. At off-design conditions a sensitivity study revealed that the k-ε RNG model records the sharpest drop in the isentropic efficiency of 8.24% at low mass flowrate reaching 30% off-design. The efficiency sensitivity is found to be less for the other tested models getting 3.1% drop in efficiency for the LRR RSM model. |
Description: | Paper No: GT2021-58883, V010T30A010. |
URI: | https://bura.brunel.ac.uk/handle/2438/29317 |
DOI: | https://doi.org/10.1115/GT2021-58883 |
ISBN: | 978-0-7918-8504-8 |
Other Identifiers: | ORCiD: Abdulnaser Sayma https://orcid.org/0000-0003-2315-0004 GT2021-58883 V010T30A010 |
Appears in Collections: | Dept of Mechanical and Aerospace Engineering Research Papers |
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