Centrifugal compressor is one of the key components in supercritical carbon dioxide(S-CO_2) cycle system

which plays a decisive role in the efficiency and stable operation of the system. Different from the traditional air compressor

the unique physical properties of S-CO_2 working medium make the internal flow field of the compressor more complex. The loss model established based on the physical characteristics of air also needs to be modified specifically to meet the performance prediction requirements of S-CO_2 centrifugal compressor. Therefore

numerical simulation is needed to investigate the internal flow field characteristics of the compressor

so as to improve the compressor performance prediction method accordingly. Firstly

one-dimensional aerodynamic parameters of the compressor were designed

and a three-dimensional model was established based on the onedimensional design parameters to analyze the characteristics of the internal flow field of the compressor. It was found that the shunt blade had a great influence on the internal flow field

and changes in the internal flow field of the impeller under varying working conditions would also cause changes in the outlet flow Angle. Based on this

The sliding factor and the calculated blade number of the compressor under off-design conditions were corrected

and the surface friction coefficient was improved to predict the performance of the compressor under off-design conditions. The numerical simulation results show that the prediction error of the improved model is significantly reduced

and the average efficiency error decreases from 2.03% to 0.16% under off-design conditions.