Effect of Rear Engine Concept Distortion on the Aerodynamic Performance of a Fan Rotor

Abstract The civil aviation industry is facing serious environmental and energy issues, and boundary layer ingestion technology (BLI) is a viable solution. However, how to ensure that the engine can work continuously under the condition of BLI inlet distortion has become the focus of research. In this paper, Unsteady Reynolds-averaged Navier-Stokes (URANS) and RANS simulation methods are used to simulate a full-annular fan, and the aerodynamic performance of NASA rotor 67 under different BLI inlet distortion is studied. The focus of analysis is on swirl distortion, which has been neglected in previous studies. The loss source in non-uniform flow field is studied by using the loss analysis method based on entropy dissipation. Results show that under side-slip conditions, the intensity of swirl distortion on windward side and leeward side is different, and swirl distortion greatly affects swirl angle distribution, which has a significant impact on fan performance. The loss is mainly located near part of the blade tip and part of the wheel hub, which is related to the structure of the BLI inlet distortion. The relative Mach number and shock wave structure change significantly in the tip region, and dramatically in the region directly affected by the distortion. The interaction between shock wave, boundary layer and tip leakage flow can cause a lot of losses. When the total dissipation decreases, the viscous dissipation caused by swirl distortion decreases and the proportion of thermal dissipation increases. The BLI distortion increases the loss mainly through the swirl distortion. In the region with weak swirl distortion, the total pressure distortion still affects the flow in the tip region.