超临界二氧化碳离心压气机设计和气动性能研究

A centrifugal compressor with rotational speed 60 000 r/min is designed according to 150 kW class supercritical carbon dioxide (SCO₂) simple Brayton cycle. The accuracy of the physical property tables of SCO₂ significantly affect the stability and accuracy of SCO₂ compressor aerodynamic performance predictions due to the dramatic variation of the physical properties of SCO₂ near the critical point. A 400×400 precision physical property table is able to lead to a reliable SCO₂ compressor aerodynamic performance. The aerodynamic performances of the designed SCO₂ centrifugal compressor in designed and off-designed conditions are numerically evaluated with the three-dimensional Reynolds-averaged Navier-Stokes (RANS) and k-ε turbulence model. The centrifugal impeller tip leakage flow is also analyzed in detail. The numerical results show that the aerodynamic efficiency of the designed SCO₂ centrifugal compressor reaches 73.2% and the pressure ratio gets 2.207 under the designed condition in consideration of the impeller tip leakage flow loss. The good performance of the SCO₂ centrifugal compressor in off-designed conditions is verified. The aerodynamic efficiency of the SCO₂ centrifugal compressor in consideration of the impeller tip leakage flow loss decreases by 14.0% compared with the case without impeller tip leakage flow effect. Three regions of the impeller tip leakage flow field, i.e. the separation flow region along the mainstream flow direction, the backflow region of the upper part in tip clearance affected by effect of adverse pressure gradient, and the flow region along the mainstream direction of lower part in tip clearance, are respectively illustrated. The designed centrifugal compressor meets the requirement of aerodynamic performance for 150 kW class simple Brayton cycle.