Investigation of Unsteady Effects on a Two-stage Counter-rotating Fan

The rotor-rotor interaction on a two-stage counter-rotating fan has been studied by unsteady numerical simulation based on non-linear harmonic method. The results show that the efficiency of the 2nd blade row above 55% span is reduced. Additionally, the unsteady effects increase the efficiency of the 2nd row below 55% span. Further analysis reveals that the unsteady benefits result from the wake boundary layer interaction, which could enhance the exchange of energy between boundary-layer and mainstream, suppress the hub corner separation