A disturbance vortex method for simulating rotor/stator interaction in turbomachinery was developed^[1,2]. This method has some obvious advantages in simulating unsteady flow in turbomachinery, such as understandable physical picture and good convergency. However, there is an important simplification in reference 1, which ignores the disturbance expansion. As a result, the computational process is greatly simplified. The main purpose of the present paper is to take the disturbance expansion into consideration with the aim to lay down a solid mathematical and physical foundation for the disturbance vortex method. Since the disturbance expansion has been taken into account, one has to solve the mass, vorticity transport and energy transport equations for disturbance motion in a coupled way. These are the main differences between the present paperand reference 1.

To validate the computational method, the unsteady flows caused by rotor/stator interaction in the first stage of NASA - 67 compressor were simulated in reference 1. And unsteady velocity correlation parameters at several locations inside the passage were compared with the experimental data. In order to find out the influence of ignoring the disturbance expansion on computational results, the same example was studied in the present paper. From the simulation results it can seen that the disturbance vortex method still converges fast even the disturbance expansion is taken into consideration.

It is noted that the additional velocity component which is needed to meet the nonpenetrate condition on the body surface is expressed by an elliptic-type Laplace equation rather than a hyperbolic-type equation even the flow is unsteady and compressible. It is also noted that setting the disturbance expansion to be zero is not equivalent to an incompressible disturbance motion.