A 3-D impeller for a micro-flowrate high-speed centrifugal air compressor(MHCAC) was designed and the performance of flow field was numerically studied.The results show that the ratio of outlet to inlet area of MHCAC impellers is less than 1.0

the efficiency of a micro-flowrate centrifugal compressor can be improved by high rotating speed;the optimum number of blades of MHCAC impellers is less than that given by empirical formula originated from the theory of high-flowrate-low-speed centrifugal compressor;the outlet angle of a MHCAC impeller is generally bigger than 60°;the overall pressure ratio and efficiency of the impeller decrease with the increase of tip clearance.The methods and results of this paper provide valuable reference for engineering design of a MHCAC in aircraft air-cycle or vapor compression refrigeration systems.