A systematic review of boundary layer ingestion (BLI) fan: Current Status and future perspectives

The distributed propulsion system has a significant potential for reducing the fuel consumption, noise and pollution emissions for the next-generation aircraft and become a current hot research topic. As the core component of the distributed propulsion system, the boundary layer ingestion fan has been continuously operating under the distorted inflow conditions, which largely degrades the aerodynamic performance of the fan itself. In turn, the degradation of the BLI fan performance will have a severe impact on the overall aerodynamic benefits achievement of the aircraft. This paper has conducted a systematic review of the boundary layer ingestion fan. Firstly, the aerodynamic benefits of BLI propulsion system has been overviewed. Then, different types of BLI fan based propulsion configurations have been introduced and the distinguished features of the distorted inflows for each configuration are analyzed in detail. Thirdly, the fan aerodynamic responses to the BLI distorted inflow are given and the influences of the BLI inflow distortion on the fan aerodynamic performances and internal flow fields are fully investigated. Subsequently, the potential performance evaluation methods, mainly the low-order computational approaches, used in the preliminary design stage of the fan have been comprehensively overviewed. Finally, the research works concerning the attempts for the fan/compressor design under non-uniform inflow condition are reviewed and some perspectives of the distortion-tolerant BLI fan design in the future have also been presented. The motivation of this work is to provide some useful guidelines for the upcoming research works concerning the BLI fan based propulsion systems.