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The influence of flow passage geometry on the performances of a supercritical CO2 centrifugal compressor

Shi Dong-Bo (Xi’an Jiaotong University, Shaanxi Engineering Laboratory of Turbomachinery and Power Equipment, School of Energy and Power Engineering, Xi’an, China)
Wang Yu-Qi (Xi’an Jiaotong University, MOE Key Laboratory of Thermo-Fluid Science and Engineering, School of Energy and Power Engineering, Xi’an, China)
Xie Yong-Hui (Xi’an Jiaotong University, Shaanxi Engineering Laboratory of Turbomachinery and Power Equipment, School of Energy and Power Engineering, Xi’an, China)
Zhang Di (Xi’an Jiaotong University, MOE Key Laboratory of Thermo-Fluid Science and Engineering, School of Energy and Power Engineering, Xi’an, China)

In this paper, based on the thermodynamic design of the supercritical carbon dioxide (sCO2) centrifugal compressor, the design idea of the flow passage geometries and the method to improve the performance of the sCO2 centrifugal compressor are discussed. With the help of commercial software ANSYS CFX, the influence of the shape of the leading edge and trailing edge is studied, and the elliptical leading edge makes the pressure ratio 10.30% higher and the efficiency 3.95% higher than the square leading edge. By changing the forward-swept angle and backward-swept angle of the leading edge, the effects of aerodynamic swept shape in sCO2 centrifugal compressor are discussed. The effect of the gap between the impeller blade and diffuser blade is discussed, and the 10 mm gap makes the performance best. The pressure ratio is increased by 2.5% compared with the original design, while at the same time the efficiency is slightly improved. In summary, based on thermal design of the sCO2 centrifugal compressor, the effects of different flow geometries are analyzed in detail.

Keywords: centrifugal compressor, sCO2, numerical simulation, flow passage geometry influence