Effects of Radially Variable Sweep Vanes on Rotor–Stator Interaction Noise

Abstract This article presents a three-dimensional semianalytic cascade model for the prediction of rotor–stator interaction noise, which includes the effects of radially variable sweep angle and chord length to better account for the latest trends in the fan-stage stator design of turbofan aero-engines. The theoretical modeling and solution method are first introduced, with special attention paid to the singularity problem brought by the nonuniformity of the stator vanes in the radial direction. The tonal rotor–stator interaction noise for stators with a radially varying sweep angle or a radially varying chord length is then calculated and analyzed. It is discovered that the phase variation in unsteady pressure loading near the stator leading edge greatly affects the resulting tonal interaction noise, while the sweep of a stator trailing edge shows less influence on the rotor–stator interaction. The duct mode characteristic of the cut-on modes has proved to be an important factor in the design of a swept stator. In addition, the soft vane design can further reduce the tonal interaction noise on a swept stator cascade.