Design of a high-loading two-stage forward swept fan and investigation on the swept-blading mechanism

The design method and the result of a two-stage high-loading forward-swept fan were presented.The design strategies of both rotor tip and stator hub forward-swepts were applied to improve the stage efficiency and stall margin.With this design, 3-D steady viscous computational fluid dynamics(CFD) technique was used to discuss the influences of forward and backward-swept rotors on the first-stage fan performance and their reasons.Two facts are found.Firstly, the swept forward and backward blade passages cause almost the same stage-efficiencies, and there exist no contrarily rotated swirling phenomena in the 3-D relative velocity fields.Secondly, the reason why the forward-swept blade can significantly increase the stall margin is that the rotor's passage shock wave tends to develop from near hub to tip according to its own intrinsic rule of developing spanwise.Both the spanwise structure and the streamwise location of the curved passage shock don't vary thoroughly with the forward or backward of the blade leading edge.So the relative distance between the shock and the leading edge increases.