The unsteady flow in a combined compressor

which consists of axial flow and centrifugal compressor impellers

was simulated numerically at mass flow of 1.15kg/s and speed of 60kr/min (design point).The objective was an in-depth analysis of the factors caused stator wake variability.In addition

a method about changing cycle and amplitude of stator wake variability was presented.The results indicate that:stator wake variability is influenced by geometric factor

up- and downstream moving rows.The blade passaging frequencies of up- and downstream rotor are related with the cycle of stator wake variability.Note that the equal blade passaging frequencies in all stages

the clocking positions have much effect on the amplitudes of stator wake variability.Moreover

along the blade’s highness

the amplitudes of stator wake variability are different

which located at low span was greater than that at mid-span and high-span.