Unsteady effects on isolated rotor exit of an axial flow compressor

An isolated axial flow compressor rotor was investigated computationally by Navier-Stokes solver. The main contributors which cause some unsteadiness downstream of the rotor were studied in detail based on the calculated 3-D flow field. The total unsteadiness in the mean flow direction was calculated and compared with experimental data. The comparison shows a good agreement for total unsteadiness prediction. The calculation results also show that both the turbulence kinetic energy and the wake velocity deficit make important contributions to the total unsteadiness downstream of the rotor. Higher turbulence kinetic energy is produced by tip leakage flow, passage vortex and hub corner stall, which results in that much unsteadiness exists in rotor tip region near the hub and inside the blade wake. This method for evaluating total unsteadiness can be the useful tools to investigate the effects of unsteady-flow mechanics.