Numerical investigation of an aggressive s-shaped compressor transition duct with combined boundary layer suction

Aggressive s-shaped compressor transition ducts are important components in the connection between the upstream boosters and the downstream high-pressure compressors. The flow has a strong three-dimensionality, which is easy to cause flow separation. Therefore, this paper takes an aggressive s-shaped compressor transition duct in a geared turbofan engine as a prototype and proposes a method for controlling the flow separation through combined boundary layer suction. The study found that combined boundary layer suction can reduce the total pressure losses to a greater extent. On the premise that the location of blade suction remains unchanged, the optimal location for the circumferential slot of hub suction is located at 20% of the axial chord length of the strut, whereby the total pressure loss coefficient decreases by about 30% compared with no suction. Besides, when the mass flow rate of suction accounts for 3% of the inlet mass flow rate, compared with the case where all suction is in the hub, the total pressure loss in another case with the mass flow rate of blade suction accounting for 0.5% and mass flow rate of hub suction accounting for 2.5% is further reduced by approximately 1.6%. The distribution of the mass flow rate for combined boundary layer suction has an optimal ratio.