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For a more comprehensive understanding of the internal flow field of a supercritical carbon dioxide (SCO2) compressor, the cavity and the labyrinth sealing structure are designed for a 150 kW simple Brayton cycle SCO2 centrifugal compressor in this paper. A numerical solution of the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equation and k-Ε (Extended Wall Function) turbulence model was used to study the aerodynamic performance and axial thrust of the SCO2 centrifugal compressor considering the cavity and sealing structure. The finite element method is used to analyze the stress and the strain characteristics of the centrifugal impeller under the combined effect of aerodynamic force and centrifugal force, and the strain of the designed labyrinth seal is also calculated. The results show that the designed aerodynamic efficiency of the SCO2 centrifugal compressor with cavity and sealing structure is 72.1% and the pressure ratio is 2.19 at the design working condition. The maximum axial thrust of SCO2 centrifugal compressor is 1 635 kN; The maximum surface equivalent stress of centrifugal impeller is 109.95 MPa, which meets the strength demand for 304 steel. The leakage flow of cavity will cause the reduction of aerodynamic efficiency of SCO2 centrifugal compressor, but under the high flow coefficient condition, the cavity leakage can alleviate the condensation phenomenon at the leading edge of the diffuser. The paper provides a reference for the analysis of the aerodynamic performance and strength characteristics of the SCO2 centrifugal compressor with cavity and sealing structure as well as the design of the sealing structure. © 2022, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.
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Journal of Xi'an Jiaotong University
ISSN: 0253-987X
Year: 2022
Issue: 4
Volume: 56
Page: 127-137