A time-marching finite difference method is presented for the numerical simulation of the three dimensional unsteady viscous flow by rotor-stator interaction in an axial transonic stage.A high-resolution scheme is adopted to capture flow shocks.The flow information of rotor and stator is exchanged by using the system of overlaid grids.In order to reduce CPU time

an implicit LU-SGS method is applied to obtain rapidly a steady state solution

from which an unsteady flow computaion can be started.A numerical example for a transonic compressor stage has been carried out.The results show a good prediction of the unsteady effects caused by rotor-stator interaction.